Replaced engine bay lines - banjo / washer leaks

[DMC-Dave]

Hi Folks,

After years of searching, I’ve finally obtained my car (‘81, manual, grey interior). Overall I think it’s in good shape and the previous owner kept it well maintained. Unfortunately I have little information on the service history and it appears to have the original style fuel lines in the engine bay. Unsure if these are the actual 41 year old lines or if they’ve been replaced at some point, but I’ve decided not to risk it and replace them with the modern stainless kit.

I know there are already some excellent posts here on this topic, and I’ve read through as many as I could find in order to prepare for the job, which I decided to attempt myself using the DPI lines, bolts, and injector holder kit.

At this point in the process I have all 13 new lines installed, DPI injector holders, new bolts & washers, new fuel filter, everything torqued to spec. After performing several rounds of pressure testing (RPM relay only, no start), I have some troublesome, very persistent leaks. I’m hoping some of you that have done this job successfully might have advice on what to try next, as I’m running out of ideas.

Here’s what I’ve done so far…

The leaks are occurring:
Main line to the fuel distributor (FD) (significant leak)
Cold start valve (CSV) to FD (minor leak)
One (probably both) lines to the pressure regulator (WUR) (moderate leaks)

Unfortunately the fuel filter appears to be leaking somewhere as well, but I’ll deal with that later.

So for the first round of pressure testing, I torqued the banjo bolts to minimum, tested, then max spec., tested. Leaking everywhere mentioned.

My assumption is that once crush washers have been torqued to max spec., they shouldn't be reused, please correct me if wrong. Can these be annealed with a blow torch? (Have never worked with this type of system before).

For the second round, I removed the bolts and replaced both top/bottom crush washers. Unfortunately the DPI kit provided no spares (seriously?), so I sourced an assortment of replacement metric washers on eBay. I eyeballed them for flatness and scratches; some were pretty bad, picked the best ones. Also made sure the fuel line end “eyes” were oriented parallel with the surfaces without requiring twisting on the lines. Ensured the correct number of washers were used, none stuck together.

https://dmctalk.org/attachment.php?attachmentid=68861&stc=1&d=1662132584

Torqued to min, then max spec., still leaking. The WUR was leaking quite badly this time, and I believe it due to the fact that my eBay washers were a bit too large in outer diameter to properly fit into the recesses on the WUR.

For the third round, I tried sanding surfaces. I realize I could be making things much worse here if not very careful; don’t want to sand unevenly and round things over, create a low spots, or introduce radial scratches in the surfaces. Used the technique of poking a hole in the sandpaper, pushing the bolt through with a crush washer behind the paper to apply even surface pressure, while spinning the bolt in place. Cut a bit of the old fuel line to help apply even pressure, see pictures. Used 1000 grit paper.

https://dmctalk.org/attachment.php?attachmentid=68863&stc=1&d=1662132596
https://dmctalk.org/attachment.php?attachmentid=68862&stc=1&d=1662132584

Replaced (again) with new top/bottom washers, and torqued to min, then max spec, and managed to stop only the CSV leak. The others remain.

So at this point, I’m kind of at a loss on next steps. I have ordered a few sets of $$$ crush washers from Delorean.com directly for my next test; maybe my eBay washers are indeed trash. I can either continue trying the same things that so far have not worked, or I’m at the point of pushing past the torque specifications on these and see what happens. I’ve already (accidentally) over torqued one of the M8 bolts on the injectors and sheered it right off, so I know first hand how fragile these things are.

Before I do that, I wanted to see if anyone had any opinions on something else to try? Is there some type of chemical sealant I can use to help? Haven't even gotten to testing the injectors yet. Did not expect the job to be this tough, is this a typical experience with squashing leaks, am I just being impatient?

[82DMC12]

First of all, you are doing the right thing replacing all of those lines. So, don't feel bad that you dove into something that was unnecessary and now you're regretting it.

I have the DPI fuel line kit successfully installed and leak-free so I am sure the lines are OK. DPI supplies crush washers that are a bit different from the washers that DMCH sells but they still work. You are right that in general the washers can only be used once. In a pinch I have been able to flip them around one time and get another use out of them but generally the smaller washers like injectors and especially the WUR for some reason don't like to be re-used. For this reason I have 6 to 12 spares of every size crush washer in my fastener organizer. I don't want to be stuck in the garage over something so critical but simple.

Since the diameter of the DPI washers are a bit different from stock, it's possible that debris/rust on the components is causing them to seat poorly. You have the right idea to look closely at that face and possibly sand it with 1000 grit or finer. Could also try a rust remover on a rag and dissolve the rusty stuff away. Something like Evaporust might work.

I too have sheered off a banjo bolt once but that was probably before I knew there was a torque spec in the book LOL. Just torque it to the maximum allowed in the chart and it should be OK.

No idea on annealing but I would not trust random copper washers from Amazon/Ebay for this.

I'd just relax until your new set of washers comes and then try again, making sure all the components are extremely clean before assembling and torqueing. I would not use any kind of sealant on any of the banjo bolts in the engine compartment however I HAVE used Hylomar AF to coat the threads on the bottom 90 degree fitting on the fuel filter to ensure it was not leaking. That stupid fitting has be extra tight or it will seep. Hylomar AF is great stuff and fixed that problem for me.

[Mark D]

What are the torque specs you're using for each hollow bolt size?

Could your torque wrench possibly be out of calibration?

[Bitsyncmaster]

I've re-used copper washers many times without leaks. Everyone says one time use.

Try installing the leaking line without one washer (you do know you need a washer on each side of the banjo fitting?) and see if the banjo bolt is bottoming out so it can't crush the washer.

[DMC-Dave]

Since the diameter of the DPI washers are a bit different from stock, it's possible that debris/rust on the components is causing them to seat poorly. You have the right idea to look closely at that face and possibly sand it with 1000 grit or finer. Could also try a rust remover on a rag and dissolve the rusty stuff away. Something like Evaporust might work.



Thanks for your reply, I noticed the outer diameter difference on the DPI washers and wondered if that's a contributing factor. It's hard to get the camera to focus on the right spot, but you can see there is some rust beyond the diameter of the original thinner washer. Sanding hasn't really helped that much though, I wonder if my trick isn't working as intended. I'll try the Evaporust suggstion. I was able to better get at the main fuel line, but that's still leaking as well.

[DMC-Dave]

What are the torque specs you're using for each hollow bolt size?

Could your torque wrench possibly be out of calibration?

Thanks for the reply. I'm using the torque specs found on page D:02:01 of the Workshop Manual:

M8 bolt: 7-9 FT LBs
M10 bolt: 9-11 FT LBs
M12 bolt: 14-17 FT LBs

I'm not certain if the workshop manual I just bought from DMCH includes later service bulletin corrections? Maybe these specs have changed?

Initially, I had the admittedly cheap (~$20) Harbor Freight click type torque wrenches, and I broke the first bolt I tightened because I didn't feel/hear the click. Oops. I then went out and bought a ~$100 ACDelco digital torque wrench, brand new. Has a calibration certificate, but I have no way to bench test it.

I'm using the DPI supplied bolts, which have 3 (slightly smaller?) holes in the walls instead of 2 like the original bolts. No idea if this makes them weaker, or if there are material differences between the 2 which negate this consideration.
See photo of original on left, DPI on right.

[MrChocky]

Hi Folks,



At this point in the process I have all 13 new lines installed, DPI injector holders, new bolts & washers, new fuel filter, everything torqued to spec. After performing several rounds of pressure testing (RPM relay only, no start), I have some troublesome, very persistent leaks. I’m hoping some of you that have done this job successfully might have advice on what to try next, as I’m running out of ideas.



Excellent, but there's 17 you generally need to replace:

102318 Injector Line #1
102323 Injector Line #2
102327 Injector Line #3
102331 Injector Line #4
102335 Injector Line #5
102339 Injector Line #6
102348 Control Pressure Line
102357 Primary Pressure Line
102370 Cold Start Injector Line
102400 Longer Frequency Valve Line
102395 Shorter Frequency Valve Line
102365 Supply Line
102359 Return Line
106979 Fuel pump feed/return/accumulator (x3)
106997 Accumulator
106983 Fuel feed front
106998 Fuel return front
106989 Fuel feed rear
106995 Fuel return rear
106287 Fuel pickup

For 22 total (23 if there's a valve on the fuel pump).

[DMC-Dave]

I've re-used copper washers many times without leaks. Everyone says one time use.

Try installing the leaking line without one washer (you do know you need a washer on each side of the banjo fitting?) and see if the banjo bolt is bottoming out so it can't crush the washer.

Thanks for the reply Dave, good tip but yes I do know that 2 washers are required per bolt. Interesting about the bottoming out theory; the DPI instructions do warn about you must use their M12 bolts on the fuel feed lines due to the lower profile on their lines. I compared the M8 and M10 bolts and they appear identical in length. I did buy the complete set of DPI bolts so I'm using those (except for the one M8 that I destroyed naturally). Nevertheless, it's worth investigating to see if they're bottoming out, thanks for the suggestion.

Also, while the car is down, I'd like to replace the RPM relay with your solid state upgrade, would you pls PM me with the details?

Not to hi-jack my own thread, but while I was jumping the RPM relay for pressure testing, I noticed an oily film all over EVERYTHING in the relay/fuse compartment (and on the module side), is that...normal? Moisture protection?

[David T]

The washers can be annealed but it is best to replace them. Get the correct size washers. If unsure just order them where you got the lines. They can be sanded with fine sandpaper if there are any minor surface defects. If the banjo bolts didn't leak before they should be OK now to reuse as long as they are not bent or starting to crack from over-tightening. Before final tightening move the line back-and-forth a little to make sure everything is fully seated. Be sure there is NO dirt AT ALL on the fittings, washers, and bolts.

[Mark D]

Thanks for the reply. I'm using the torque specs found on page D:02:01 of the Workshop Manual:

M8 bolt: 7-9 FT LBs
M10 bolt: 9-11 FT LBs
M12 bolt: 14-17 FT LBs

I'm not certain if the workshop manual I just bought from DMCH includes later service bulletin corrections? Maybe these specs have changed?

Initially, I had the admittedly cheap (~$20) Harbor Freight click type torque wrenches, and I broke the first bolt I tightened because I didn't feel/hear the click. Oops. I then went out and bought a ~$100 ACDelco digital torque wrench, brand new. Has a calibration certificate, but I have no way to bench test it.

I'm using the DPI supplied bolts, which have 3 (slightly smaller?) holes in the walls instead of 2 like the original bolts. No idea if this makes them weaker, or if there are material differences between the 2 which negate this consideration.
See photo of original on left, DPI on right.

I don't think the service bulletin ever revised the banjo bolt torque specs, so the manual should be correct.

https://cdn.preterhuman.net/texts/automotive/delorean/ST-09-7.81.pdf

There was one other bulletin but I think it was just related to the ball joint torque specs.

So it sounds like you're tightening everything down to the correct specs and it's tough to argue with a digital torque wrench. Not sure what else it could be that's causing the leaks. You'd have to have a surface imperfection on either the hose banjo, bottom surface of the bolt, or on the fuel distributor / WUR where you're seeing leaks. You already said you've been using 1000 grit to try and refine those surfaces. Is there anything else visually noticeable like a deep scratch or pitting on any of those surfaces?

For the M10 and M12 bolts you're in less danger of actually breaking them if you exceed the torque values, but the smaller M8's for the injector lines are closer to the point of breaking if you go any higher than what is listed.

[Delorean Industries]

Hi Dave, we would reach out directly but have sold line kits to multiple Dave's recently and are unsure which one to contact. We haven't received any requests for technical advice from you, but I can be reached directly at [email protected] to further assist with any technical help required.

Regards
Josh Bengston
DeLorean Industries

[Helirich]

I've re-used copper washers many times without leaks. Everyone says one time use.

Try installing the leaking line without one washer (you do know you need a washer on each side of the banjo fitting?) and see if the banjo bolt is bottoming out so it can't crush the washer.

This! I can’t say I’ve used them “many” times, but a few times and they worked fine. It’s kind of like unlock nuts. Technically, you should throw them away after one use, but they work again. (Even the locking part)

[DaraSue]

I've taken the lines off the distributor every time I've had my intake off (4 or 5 now, I've lost count) and every time I've had to tighten some of the bolts past spec. I've used washers from a couple of different vendors and also the ones off the shelf from O'Reilly and they've always been fine once I got them tight. I tighten them to the max and then another fraction of a turn if they need it. Haven't broken one yet, knock on wood...

[DMC-Dave]

I've taken the lines off the distributor every time I've had my intake off (4 or 5 now, I've lost count) and every time I've had to tighten some of the bolts past spec....

I SWEAR the main fuel line bolt was way over torqued, took both hands on the ratchet, nearly all my strength to break it free. I felt the engine move against the mounts before it let go. Maybe rust had something to do with it but still, no way that was spec, thought I would need to get out the breaker bar.

[DMC-Dave]

Hi Dave, we would reach out directly but have sold line kits to multiple Dave's recently and are unsure which one to contact. We haven't received any requests for technical advice from you, but I can be reached directly at [email protected] to further assist with any technical help required.

Regards
Josh Bengston
DeLorean Industries

Thanks Josh, I'll reach out, honestly hadn't thought of that.

Just to be clear, did not intended this post as criticism of DPI products, I like them fine so far. Admittedly I was a little disappointed extra crush washers weren't included in the kit as it seems to me unlikely to successfully complete the install with just the exact number, but at this point I've been through so many a few extra wouldn't have helped anyway. I should have ordered another complete set.

[mark w]

Ive seen some new bolts that are too long, and they bottom out before enough crush can be achieved on the copper washer.
using the correct diameter washer is key too, so that enough crush is achieved

when doing fuel lines...

rule 1- always buy way more washers than needed.
rule 2 - NEVER over torque in an attempt to try to stop a leak. you can crack the FD or the WUR, etc
rule 3- bolt length and washer thickness is critical

[MrChocky]

Ive seen some new bolts that are too long, and they bottom out before enough crush can be achieved on the copper washer.
using the correct diameter washer is key too, so that enough crush is achieved

when doing fuel lines...

rule 1- always buy way more washers than needed.
rule 2 - NEVER over torque in an attempt to try to stop a leak. you can crack the FD or the WUR, etc
rule 3- bolt length and washer thickness is critical

rule 4 - you are only allowed to drop 2 washers in the valley.

[Jonathan]

Ive seen some new bolts that are too long, and they bottom out before enough crush can be achieved on the copper washer.
using the correct diameter washer is key too, so that enough crush is achieved

when doing fuel lines...

rule 1- always buy way more washers than needed.
rule 2 - NEVER over torque in an attempt to try to stop a leak. you can crack the FD or the WUR, etc
rule 3- bolt length and washer thickness is critical

I had this happen to me too. Was the six bolts used on the injectors. Just a little bit too long and they bottomed out before getting a good seal. Ended up using my old bolts while I ordered different replacements.

Do you have your old bolts still? You could try using those in the places where it's still leaking.

[DMC-Dave]

I had this happen to me too. Was the six bolts used on the injectors. Just a little bit too long and they bottomed out before getting a good seal. Ended up using my old bolts while I ordered different replacements.

Do you have your old bolts still? You could try using those in the places where it's still leaking.

Yeah, I did keep the old bolts so I can revert back if necessary. I notice (some) of the crush washers seem to have a flat side and a rounded side; does washer orientation matter?

[Jonathan]

I'm using the DPI supplied bolts, which have 3 (slightly smaller?) holes in the walls instead of 2 like the original bolts. No idea if this makes them weaker, or if there are material differences between the 2 which negate this consideration.
See photo of original on left, DPI on right.

Like what you've shown in this picture, I suspect it is the subtle difference in the length of your bolts that is causing the leaks. Put the old bolts back in at the places you're having trouble and see if the leaks stop.


Yeah, I did keep the old bolts so I can revert back if necessary. I notice (some) of the crush washers seem to have a flat side and a rounded side; does washer orientation matter?

I'm not aware of the two sides of the copper sealing washers being different. It shouldn't matter. You can use them over again without worry. That's just people being overly cautious or impractical and quoting manuals too much.

[Ron]

Yeah, I did keep the old bolts so I can revert back if necessary. I notice (some) of the crush washers seem to have a flat side and a rounded side; does washer orientation matter?

The washers should be flat on both sides.
When new, they are soft and crush to form a good seal when torqued down. Torquing them down makes them harder. You can make them soft again by annealing them. (Heat them up until they glow then quench them. Then dress both sides using a circle eight motion while pressing down on fine sandpaper lying on a flat surface. Since you are dealing with gasoline under high pressure, it's usually not worth the risk/effort, imho...Get new ones.)

[mhanch]

I did this and used washers from Delorean Go, anmd also ones from a generic kit from Amazon. they are identical. there's no reason to risk reusing a washer. I also used the old bolts and they sealed perfectly. I had help from Toby Perterson to do the main input line and filter since that was more complicated than the top lines, and he gave the setup a clean bill of health. Good on you for doing this and hope it seals up!

[Bitsyncmaster]

The washers should be flat on both sides.
When new, they are soft and crush to form a good seal when torqued down. Torquing them down makes them harder. You can make them soft again by annealing them. (Heat them up until they glow then quench them. Then dress both sides using a circle eight motion while pressing down on fine sandpaper lying on a flat surface. Since you are dealing with gasoline under high pressure, it's usually not worth the risk/effort, imho...Get new ones.)

I don't think you quench them after heating to anneal. At least when I was doing aircraft welding to anneal (take out stress from welding) you let the steel cool slowly.

[Ron]

I don't think you quench them after heating to anneal. At least when I was doing aircraft welding to anneal (take out stress from welding) you let the steel cool slowly. My understanding is that it works differently with copper -- With copper, how fast you quince it does not matter a lot.

I know that jewelers heat and quench copper to soften it after working it. (Seems crushing it would be similar to me.)

Always worked for me...:dunno:

[DaraSue]

When I was reinstalling mine the first time I called up a DMCH franchise in a fit of frustration after going through several sets of washers and still getting leaks at max torque and the way I remember it, they told me tightening the bolts until the leaks stopped was fine as long as you didn't tighten them enough to break the bolt. When I do it I torque with a torque wrench first and then go over them with a regular ratcheting socket wrench and tighten them (gently) until a small amount of pressure doesn't turn them any more. So far, no issues I'm aware of. A buddy of mine talked to the same shop and they also told him they reuse crush washers all the time :hmm:

(When I first got the car I had some VOD work done by a local shop so maybe they screwed something up and that's why I have to overtighten them now, idk...)

[mhanch]

This is identical to the set I have: https://www.amazon.com/dp/B06Y1HQ1MF/ref=sspa_dk_detail_5?ie=UTF8&psc=1&pd_rd_i=&pd_rd_i=B06Y1HQ1MFp13NParams&s=industrial&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw

$12 in washers so I don't screw up my ~$65k car. or you can reuse washers and save some money.

[r00b]

I've had some washers with one side that looked like it had been machined flat, it had scratches like you had put it down on sandpaper and dragged it in one direction. Of course they leaked, I had to sand it sort of the way you are sanding them to ensure they wouldn't leak. I make banjo to quick connect fittings and then make my own fuel lines with nylon hose, If I need to remove or replace a line I leave the banjo fitting stays behind and I just remove the line. It makes replacing the fuel filter a breeze but I do need some copper washers for that when I swap over the fittings to the new filter.

68886

When I had this idea, it was hard to find fittings like these. I had to make my own, so I have all the tools now to do it. If there's interest I could make more and put them up for sale. Once I set up my lathe I'll be able to make these in stainless, but that might not be fore few months. Until then I can make the plated versions.

I also made the ends on the hard lines quick connect.

[todd1561]

Not to hi-jack my own thread, but while I was jumping the RPM relay for pressure testing, I noticed an oily film all over EVERYTHING in the relay/fuse compartment (and on the module side), is that...normal? Moisture protection?

Maybe off-gassing from the battery right below?

[MrChocky]

My understanding is that it works differently with copper -- With copper, how fast you quince it does not matter a lot.
:

And this is how you get into a jam.

[dmcman73]

When I was reinstalling mine the first time I called up a DMCH franchise in a fit of frustration after going through several sets of washers and still getting leaks at max torque and the way I remember it, they told me tightening the bolts until the leaks stopped was fine as long as you didn't tighten them enough to break the bolt. When I do it I torque with a torque wrench first and then go over them with a regular ratcheting socket wrench and tighten them (gently) until a small amount of pressure doesn't turn them any more. So far, no issues I'm aware of. A buddy of mine talked to the same shop and they also told him they reuse crush washers all the time :hmm:

(When I first got the car I had some VOD work done by a local shop so maybe they screwed something up and that's why I have to overtighten them now, idk...)

Once "righty tighty" becomes "righty loosey", you'll now at what point to stop.

[Chris 16409]

Dave, if you are interested in Dave McKeen's RPM relay I sell compatible cores so you can keep your original as a spare. Let me know if you are interested. I'll send you a PM as wll.

[DaraSue]

Once "righty tighty" becomes "righty loosey", you'll now at what point to stop.

That's pretty much what the tech I talked to said. It may be worth noting that I'm a 5'3" 120-something lb female so I'm probably not turning the ratchet with the same force as a 200 lb male. IIRC it's usually taken less than 1/4 of an extra turn to get it tight so obviously don't crank the wrench like you're closing a fire hydrant.

[DMC-Dave]

Thanks for the suggestions everyone. I only have time to work on my vehicle on the weekends, so progress is a little slow.

One correction; earlier I mentioned the original/new M8 bolts were the same length, but that is not the case! I should have measured instead of just eyeballing; lining them up opposite each other clearly shows this length difference (photo). The DPI bolts are 1mm longer according to my calipers, so bottoming out could be the issue?

I tried Dave’s suggestion of omitting one washer to test this, and for the WUR bolts at least, it does not appear to be bottoming out. I do wonder about the injectors now though that Jonathan mentioned it, which I haven’t yet tested and will probably need to revisit. It was also suggested that rusted / damaged threads at the bottom of the WUR might cause bottoming out; I used an endoscope down the hole and the threads seem OK.

I did receive the new washers from DMCH and I spent some more time sanding / cleaning surfaces, and trying evaporust. Installed again and torqued to max and tested; I thought I had it! But..after a few mins under pressure I started to get fuel weeping from the same spots (plus a few new; ostensibly now that the system achieves higher pressure). One step forward two steps back. Over torqued them by about 1/8th to 1/4th turn (as much as I dared) and tested again, but still weeping.

I wonder if lubricating the banjo threads might allow higher tensions on the bolts to be achieved, while lowering torsional stresses that might otherwise shear the bolts. Although I realize lubricated torque specs are lower, not sure by how much on these bolts, has anyone tried this?

Damn, this has become very frustrating. I’m not a mechanic but I’ve done my share home garage work; tire rotations, oil changes, tune ups, etc. all no problem for me. I didn’t expect this job to be kicking my arse so. This weekend I’ll try another round using the old bolts in the problem areas. I’m cleaning them up now.

If that doesn’t work I may need to admit defeat and try to find some place to tow it to and have the pros take a crack at it. I’m about 12 weekends into this job, when I expected only 2 or 3; I’ve lost most if not all of the driving season to it at this point, I should have just driven the car and not worried about it until next spring. Gah!

[DMC-Dave]

Has anyone used or heard anything about Silver Arrow service in Hudson NH?

https://silverarrowservice.com/delorean-2/

Website indicates experience with PRV (although it's kind of hidden on their site).

[Rich]

One correction; earlier I mentioned the original/new M8 bolts were the same length, but that is not the case! I should have measured instead of just eyeballing; lining them up opposite each other clearly shows this length difference (photo). The DPI bolts are 1mm longer according to my calipers, so bottoming out could be the issue?

I wonder if lubricating the banjo threads might allow higher tensions on the bolts to be achieved, while lowering torsional stresses that might otherwise shear the bolts. Although I realize lubricated torque specs are lower, not sure by how much on these bolts, has anyone tried this?

Go back to your original bolts since you know they weren't bottoming out. Aside from wanting a "new bolt look" there's seldom a need to replace them unless they had stripped threads. Your photo shows good threads.

Again, you'll want to use a new pair of factory-spec washers each time you torque down one of these fittings. While it's possible for them to be reused they don't always seal well. At this point you want no risk.

Further notes:
Do NOT lube the banjo bolt threads.

Check to be sure your torque wrench is set correctly. Some of them have vernier marks that are hard to read; you can be off one way or the other by a whole turn.

Two washers per fitting - be sure you have one washer above AND one washer below each banjo fitting as you fit the bolt to the fitting. You probably noticed this when you took it apart.

Closely inspect each side of any "leaking" banjo fittings - both faces must be free of any nicks or scratches. Don't used damaged ones.

[rjd2]

I know that they are a bit pricey, but maybe a year or two ago I switched from torque wrenches to a digital torque meter, and never looked back. I have used it on every significant fastener in an engine bay since. I just found the traditional clicking mechanical wrenches to be too prone to user error. So instead of it clicking, you read the meter, and stop where you want. you can tighten to a level of accuracy that's pretty amazing.

https://www.summitracing.com/parts/bkm-15-2146?seid=srese1&gclid=CjwKCAjwg5uZBhATEiwAhhRLHoVc45BVwDbbbn7RxPCT GzRFFaGzWe77YdGWDdDNBCVJuJL-6yPU5hoCyhcQAvD_BwE

Also, I don't know if this would help, but I often use aluminum crush washers in lieu of copper. Casey Putch from Genius Garage suggested them over copper once, and I have found them to be just as good. I have also reused copper washers multiple times, but if you are smashing the hell out of them then maybe they can leak?

The fact you are getting leaks on a number of connections would lead me to believe there's a systemic issue-tool, part, or otherwise. Stick with it. You'll get it. I havent done it on a DMC just yet, but on other vehicles I have bridged the pins of the fuel pump relay to get it to run. It's a nice way to check for pressure without having to run the engine. Just a thought, if it stresses you out to run the engine just to find leaks.

[Bitsyncmaster]

Never had any leaking problems with my injection parts but I did have a leaking otterstat (screw in type) which seals with a copper crush washer. To get that to seal I used two crush washers instead of one. I suspect the otterstat pipe did not have enough chamfer and the threads blocked it from pulling down enough.

[Chris 16409]

Never had any leaking problems with my injection parts but I did have a leaking otterstat (screw in type) which seals with a copper crush washer. To get that to seal I used two crush washers instead of one. I suspect the otterstat pipe did not have enough chamfer and the threads blocked it from pulling down enough.

Hey Dave I had to use Teflon tape to get it to seal. The included washer doesn’t do much.

[Chris 16409]

If you get the new banjo bolts from D-Go you must get their thicker M8 washers to use them on the injectors. The bolts are longer than stock. I don’t recommend changing bolts either unless they are corroded or damaged. You should not have to sand the washers down or any of that. I’ve changed out about a dozen fuel lines for owners and have never faced the issues you describe.

[Jonathan]

Something else I thought of that the OP might want to double check is the thickness of the ends of the new fuel lines when compared to the originals. If you are making a sandwich at each connection of one hoop on the end of the line together with two copper washers and being concerned if the bolts are now too long (or too short), that line hoop thickness will be important too. If you take one of your old ones and just put it side by side with the corresponding new one, you should be able to tell pretty quickly if they are the same thickness or not.

For the longer bolts bottoming out, you can also take any of those locations and just gently thread in the bolt with nothing attached to it. Stop when it gets bottomed out and measure the distance of what is now left between the top edge of what you are connecting to and the bottom edge of the head of the bolt. If that distance leftover is greater than the thickness of two washers plus the thickness of the hoop, you're going to get leaks.

[poidog]

I know I'm late to this party, but I recently changed my fuel lines over to stainless steel lines as well. My M10-12 sealed up nicely around torquing spec but the one M8 that supplied the frequency valve I could not get a good seal on without it weeping within torque specs. It eventually sealed up the weep when tightening to about 14 lbs of torque. I just think the crush washer wasn't crushing all the way until it got some additional torque on it.

[Trevino08]

Thanks for the suggestions everyone. I only have time to work on my vehicle on the weekends, so progress is a little slow.

One correction; earlier I mentioned the original/new M8 bolts were the same length, but that is not the case! I should have measured instead of just eyeballing; lining them up opposite each other clearly shows this length difference (photo). The DPI bolts are 1mm longer according to my calipers, so bottoming out could be the issue?

I tried Dave’s suggestion of omitting one washer to test this, and for the WUR bolts at least, it does not appear to be bottoming out. I do wonder about the injectors now though that Jonathan mentioned it, which I haven’t yet tested and will probably need to revisit. It was also suggested that rusted / damaged threads at the bottom of the WUR might cause bottoming out; I used an endoscope down the hole and the threads seem OK.

I did receive the new washers from DMCH and I spent some more time sanding / cleaning surfaces, and trying evaporust. Installed again and torqued to max and tested; I thought I had it! But..after a few mins under pressure I started to get fuel weeping from the same spots (plus a few new; ostensibly now that the system achieves higher pressure). One step forward two steps back. Over torqued them by about 1/8th to 1/4th turn (as much as I dared) and tested again, but still weeping.

I wonder if lubricating the banjo threads might allow higher tensions on the bolts to be achieved, while lowering torsional stresses that might otherwise shear the bolts. Although I realize lubricated torque specs are lower, not sure by how much on these bolts, has anyone tried this?

Damn, this has become very frustrating. I’m not a mechanic but I’ve done my share home garage work; tire rotations, oil changes, tune ups, etc. all no problem for me. I didn’t expect this job to be kicking my arse so. This weekend I’ll try another round using the old bolts in the problem areas. I’m cleaning them up now.

If that doesn’t work I may need to admit defeat and try to find some place to tow it to and have the pros take a crack at it. I’m about 12 weekends into this job, when I expected only 2 or 3; I’ve lost most if not all of the driving season to it at this point, I should have just driven the car and not worried about it until next spring. Gah!

Having the same problem. Where did you end up?

[hjhjr]

The copper crush washer hardened with use They can be made malleable by heating red hot and cooling. They will seat better.

[rjd2]

Couple thoughts/data points to help:

1-my 2 cents: fastening the banjo bolts will likely be done best with fresh copper/aluminum washers, proper torque, done. As soon as you get into sanding washers/surfaces/etc, you are probably making the seal less likely to be liquid tight.

2-my driver car had new SS supply lines, but the frequency valve lines were original, so I replaced them today. I will often use a torque meter when removing fasteners, just to give me a benchmark for "what already works". The larger banjo bolt at the FD that fastens the larger diameter frequency valve hose(19mm head) was at 42nM, and hadnt stripped. Do I suggest you do that? god no. but you could theoretically use it as a ceiling of sorts. I don't know what the factory torque is on the banjo bolts, but I'm guessing its in the 10-20nM range. if you don't have a torque meter, and can afford one, I strongly suggest one. worth their weight in gold!

[DMC-Dave]

Not really in a good place unfortunately, replaced the WUR banjos with the original bolts after soaking for a day in evaporust, new DMC washers, torqued, then over torqued, still weeps a little bit at both. Over torqued the main fuel line and tested, that held for several hours, no apparent leaks, but when I checked the next day it had weeped a bit. Small amount, but not zero. I can tell because the paper towel turns yellow. Seems odd that I’d see it the next day given the system slowly depressurizes, I suspect the leak occurred immediately and it just took a day to turn color.

Right now I’m back under the car working on the fuel filter leak, which is by far the largest; it would be nice to run a test without leaking fuel below; it’s leaking at the compression fitting so I need to figure out my approach there. Leaning towards Teflon tape on the ferrule and threads, maybe some light sanding if I see any major scratches. Little concerned about contaminating the fuel line though. I read in another thread here that lubricating the compression fitting mating surfaces and threads is recommended, so might try that first.


Having the same problem. Where did you end up?

[Ron]

Not really in a good place unfortunately, replaced the WUR banjos with the original bolts after soaking for a day in evaporust, new DMC washers, torqued, then over torqued, still weeps a little bit at both. Over torqued the main fuel line and tested, that held for several hours, no apparent leaks, but when I checked the next day it had weeped a bit. Small amount, but not zero. I can tell because the paper towel turns yellow. Seems odd that I’d see it the next day given the system slowly depressurizes, I suspect the leak occurred immediately and it just took a day to turn color.

Right now I’m back under the car working on the fuel filter leak, which is by far the largest; it would be nice to run a test without leaking fuel below; it’s leaking at the compression fitting so I need to figure out my approach there. Leaning towards Teflon tape on the ferrule and threads, maybe some light sanding if I see any major scratches. Little concerned about contaminating the fuel line though. I read in another thread here that lubricating the compression fitting mating surfaces and threads is recommended, so might try that first.
$.02
About the Teflon tape...fuel shouldn't get to the threads, or on the outside of a ferrule, to leak.
Just be clean...lube ok imho.

[DMC-Dave]

Unfortunately starting out with completely new bolts and washers torqued to min then max spec still resulted in leaks, so sanding seemed the next logical step based on my research. That being said, I did have some reservations; a close examination of the surface of the bolts showed a slight texture - very small ridges in concentric circles, not sure if this is left over from some machining operation or if it’s intentional to increase the surface area? Regardless, I did not sand the bolts, only the rusted surfaces on the WUR and FD. Have not tried aluminum washers but it’s worth a shot at this point.


Couple thoughts/data points to help:

1-my 2 cents: fastening the banjo bolts will likely be done best with fresh copper/aluminum washers, proper torque, done. As soon as you get into sanding washers/surfaces/etc, you are probably making the seal less likely to be liquid tight.

2-my driver car had new SS supply lines, but the frequency valve lines were original, so I replaced them today. I will often use a torque meter when removing fasteners, just to give me a benchmark for "what already works". The larger banjo bolt at the FD that fastens the larger diameter frequency valve hose(19mm head) was at 42nM, and hadnt stripped. Do I suggest you do that? god no. but you could theoretically use it as a ceiling of sorts. I don't know what the factory torque is on the banjo bolts, but I'm guessing its in the 10-20nM range. if you don't have a torque meter, and can afford one, I strongly suggest one. worth their weight in gold!

[Ron]

Just reread the thread.
I agree - You shouldn't be having this much trouble with leaks. Something odd is going on...
If I were you , I'd order a set of washers from Josh to match the new ones and ask him about the torque.

Can you post a good pic of the FD port(s)?

[DMC-Dave]

I don't have any before pictures of the FD unfortunately, but here are a couple photos after sanding surfaces; main line and cold start were initial trouble spots, although after over torquing, only the main appears to be still weeping. I haven't yet tested the injector lines however so more leaks are anticipated, if history is any guide. In most cases now the amount of fuel leaking is very small, but frustratingly, not zero - see highlighted photo.

You may notice a lot of paper towel fibers shown on the lines in the photos, which I realized can be problematic for creating tight seals; these were early photos and I've adopted the practice of only using cloth rags and canned air to clean the areas before torquing down.


Just reread the thread.
I agree - You shouldn't be having this much trouble with leaks. Something odd is going on...
If I were you , I'd order a set of washers from Josh to match the new ones and ask him about the torque.

Can you post a good pic of the FD port(s)?

[Jonathan]

I agree with Ron in what he said about you shouldn't be having this much trouble and something weird must be going on...

Is there any chance your torque wrench calibration or function is off? Like maybe you thought you were torqueing the bolts to a certain value, but in reality you weren't?

Can you show us the torque wrench you are using and the values you are torqueing to on these bolts?

[rjd2]

I'm only gonna say this to be helpful, so I'm not trying to be a jackass here, just trying to be logical in the interest of helping you solve your problem:

If you are still having trouble, using the correct size copper washers, my money is on the sanding of the FD surfaces caused them to be "out of plane" to a degree the washer cant compensate. Again, not trying to be an ass, but I would never do sand surfaces of rare devices like that. I know you can't go back in time, but those surfaces likely were machined perfectly flat. It's VERY hard to go at a flat metal surface with your hand and sandpaper and come away with a perfect surface.

The good news, in my eyes, is this. those surfaces on your FD are either f**ked or they arent. So "over torquing" the banjo bolts is, in some way, maybe a risk worth taking? aluminum has more give than copper, as I understand it-copper apparently has a higher "desire to return to it's original shape". It may be worth trying aluminum.

Also, if you are jumpering the FP relay, one thing I have done in the past with fiber washers is to run the pump, if the leak is small, and tighten the bolt in real time, continually wiping the joint with a paper towel or rubber glove. you just go til you can't feel leakage.

[DMC-Dave]

100% agree it shouldn't be this much trouble, this fuel system design seems absolutely crazy to me. I count 23 bolts in the engine bay; 22 have 8 mating surfaces each which may potentially leak, and the FD return has 12 surfaces (3 washers), for a total of 188 surfaces that may potentially leak highly flammable fuel into a hot engine bay. I don't know how this could have passed the engineering safety review, horrible design IMO (obviously somewhat tinged by my current predicament).

Regardless, to begin I was using some cheap click type torque wrenches (harbor freight) that I had, I find these a bit finicky because as I recall you're supposed to dial the setting all the way up/down before setting the torque value. I sheared one of the bolts using these as I mentioned earlier, so I purchased an AC-Delco digital torque wrench just specifically for this job. Presumably there is a strain gauge of some form, internally calibrated to measure torque in ft-lbs, in-lbs, N-M, etc. Beeps with increasing frequency to solid tone when torque is reached (sometimes it's hard to read the digital readout due to angle). Pretty straight forward to use.

I'm using the torque specs found on page D:02:01 of the Workshop Manual:

M8 bolt: 7-9 FT LBs
M10 bolt: 9-11 FT LBs
M12 bolt: 14-17 FT LBs

I don't believe that I'm using the tools incorrectly, or the wrong torque values, but correct me if I'm wrong, although at this point the torque values seem more of a suggestion than a rule.

Currently my thinking is that there may be some surface imperfection I can't see, such as being out of plane on the FD, or maybe the new fuel lines were damaged or deformed some how. I was careful handling and gave them a cursory inspection before installation and they seemed fine to my eye. It may also be that I must use the DPI provided crush washers with their lines; I do notice the washer diameter is larger on DPI original washers vs the DMCH ones I purchased. Everything was pretty crusty in the engine bay (see injector photo) which is weird because the car is otherwise pretty cherry.

I may try reinstalling the old lines again just to see what happens, do these leak now? I can do that for the WUR but I ended up having to cut the main line to get the fuel filter out so that option is not available. Unfortunately, next steps seem to me to be things such as removing and possibly replacing the WUR, or FD cover, or ordering (some) new lines from somewhere else; all these are quite expensive shot gun approaches that I'm not too keen on.


I agree with Ron in what he said about you shouldn't be having this much trouble and something weird must be going on...

Is there any chance your torque wrench calibration or function is off? Like maybe you thought you were torqueing the bolts to a certain value, but in reality you weren't?

Can you show us the torque wrench you are using and the values you are torqueing to on these bolts?

[rjd2]

how many locations do you have leaking? is it just one? if you name the exact fittings that are leaking, that can help deduce. in short, if you have one leaking, that could be dirt/product error. if you have several leaks, being frank here, this is likely user error or a "resurfacing" issue, related to sanding of the surfaces. if you have a leak at the WUR and at the FD, did you resurface both of those?

i think it's hjighly unlikely any of the major retailers sold you lines with errors of the kind you are talking about.

if you managed to shear a bolt off by sheer torque,you are using waaaay too much torque. banjo bolts dont have the integrity/stability of a normal bolt; you're lucky this is the case, cause if you stripped the threads of either, you'd be in a much worse position. is it possible that you have been torquing the living shit out of the bolts, backing them out, and then retightening them? if so, i could see that being the culprit.

[Ron]

...
all these are quite expensive shot gun approaches that I'm not too keen on.
For a first shot, I'd try only replacing the ones that leak with old ones first.:)

[Aaron Cake]

I know this is a 3 year old topic but having just read through it, I didn't see this mentioned.

If having problems sealing with the crush washers alone, try a Doughty Seal.

See the attachment for examples.



I've used these for years in the rotary world to replace the stock crush washers on fuel rails, oil lines, etc.

Available at most hydraulic shops though at several times the price of a crush washer.

The advantage they have is that the inner rubber o-ring makes the primary seal and confirms to uneven surfaces. The outer ring keeps the o-ring encapsulated and also serves as a secondary crush washer.

[r00b]

They're also good for the oil drain plug, you can get them on belmetric

[DMC-Dave]

Those look great, a better way to make the seal, definitely picking some up for the workshop. Thanks for the tip.

As a postmortem, I finally did stop the leaks through a combination of over torquing and using the original banjos in a few cases.