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?a...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?a...1&d=1662132596
https://dmctalk.org/attachment.php?a...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/au...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.