Replacing the Frequency Valve and Return hoses

[DMC-81]

Taking advantage of the cooler weather these past few weeks, I decided it is time to replace the 3 remaining fuel lines with my previously purchased DeloreanGo braided stainless steel replacements. Doing so will relieve my concern about the condition of the old lines, especially the high pressure side of the FV. Plus, I will have all 13 lines new and matching. I will post my steps/things learned here as I couldn't find a specific thread on these hoses.

Here is a picture of the original hoses:



Here are the parts ready to install:


They are:
1) long high pressure FV hose (102400)
2) short low pressure FV line (102395A)
3) return hose (102359SS)

I made some slight changes to ensure these hoses will match my other 10 hoses, and I'll detail these here as well.

Most notably, the M12 banjo AN/JIC fitting on the return line had a blue anodized finish (as they are aluminum). I believe they also have a black anodized finish version. To make it match my black and silver color scheme, I stripped the blue finish off with oven cleaner, and polished it to better match the silver fitting finish on the rest of the lines. The same can be done to the black fitting.

Here is a close up of the finished fitting. After soaking in the oven cleaner for a few minutes, I rinsed it off, and sanded the rest of the anodized finish off with 320, then 1000 grit sandpaper. Next I polished it with a dremel mounted buffing wheel and rubbing compound. Finally a hand polish with Mother's Mag and Aluminum polish to a mirror shine:


To be continued...

[Parzival]

let me know when you plan to do this, I'll be happy to come lend a hand!

[DMC-81]

let me know when you plan to do this, I'll be happy to come lend a hand!

Thanks Austin! Although I think this task is a one person job and I'm posting after the fact.

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Here is the clamp and electrical connection disconnected:

The 6mm bolt and shaker washer goes in the rear valve cover boss hole, and there is a metal wire around the male side of the connector that I carefully removed to enable squeezing the plastic tabs that hold it in place. I was very careful not to twist or bend the plastic housing on the FV out of concern that it may crack and fail.

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I removed the coil cover (110277) to reveal the return line to hard line connection, and the needed space to separate them.


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I removed the 8mm hard line swivel nut (106981) from the metric compression male adapter (106994):


Here's a great tip: Position two 17 mm wrenches of the same length, one on each fitting and lined up to squeeze them together with one hand ( make sure you are turning the swivel nut counterclockwise). Then squeeze them axially, (avoid lateral forces). DO NOT use a wrench in each hand, as this introduces lateral forces that will work against you and or bend the hard line. Use this one hand technique to loosen and tighten the fittings. I learned this tip from the DeLorean UK forum and it worked fantastic: http://www.deloreaneurotec.uk/viewto...9b24e2e34dc612

I also used WD-40 liberally 2 or 3 times and let it sit for 2 days on the two fittings here before attempting the removal, and used a 1" length of PVC pipe for extra leverage in this tight space as the fittings were very tight.

[SpudMurphy]

I removed the 8mm hard line swivel nut (106981) from the metric compression male adapter (106994):

Here's a great tip: Position two 17 mm wrenches of the same length, one on each fitting and lined up to squeeze them together with one hand ( make sure you are turning the swivel nut counterclockwise). Then squeeze them axially, (avoid lateral forces). DO NOT use a wrench in each hand, as this introduces lateral forces that will work against you and or bend the hard line. Use this one hand technique to loosen and tighten the fittings. I learned this tip from the DeLorean UK forum and it worked fantastic: http://www.deloreaneurotec.uk/viewto...9b24e2e34dc612

I also used WD-40 liberally 2 or 3 times and let it sit for 2 days on the two fittings here before attempting the removal, and used a 1" length of PVC pipe for extra leverage in this tight space as the fittings were very tight.

Woo hoo - somebody used and acknowledged my tip - thanks for that acknowledgement . It works great doesn't it?

[DMC-81]

Woo hoo - somebody used and acknowledged my tip - thanks for that acknowledgement . It works great doesn't it?

You're welcome! It sure does work great!

[Parzival]

Dana, your return line install looks amazing. Did I notice you're line appears to have some slack in it. I did mine and it hardly reaches? Is there any danger with this line being pulled tight like this?
Yours

vs mine

[Jonathan]

Taking advantage of the cooler weather these past few weeks, I decided it is time to replace the 3 remaining fuel lines with my previously purchased DeloreanGo braided stainless steel replacements. Doing so will relieve my concern about the condition of the old lines, especially the high pressure side of the FV. Plus, I will have all 13 lines new and matching. I will post my steps/things learned here as I couldn't find a specific thread on these hoses.

To be continued...

Whoo hoo Dana! Great thread! I need to do this myself... but am waiting for the weather and temperature in my garage to go back UP, lol. After you sir...

IMG_0090.jpg

[DMC-81]

Whoo hoo Dana! Great thread! I need to do this myself... but am waiting for the weather and temperature in my garage to go back UP, lol. After you sir...

IMG_0090.jpg

Thanks Jonathan!

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Return Hose Removal continued:

I separated the 8mm cutting ring/”Olive”/ bulk ring (106980) from the metric tube compression adapter (106994) . I applied needle nose vice grips in the rear part of the cutting ring and used a 17mm wrench to turn the adapter clockwise against the cutting ring. As before, try to focus your movement axially, (avoid lateral forces).


After a couple tries while adjusting the tension on the vice grips (tight enough to grip, but not tight enough to deform the ring/tube), I had success. Here are the parts separated. I read that the metric compression fitting can be re-assembled assuming that the tube and fitting parts are not damaged. Mine were is great shape, so I gently cleared the burrs off the cutting ring with 1000 grit sandpaper and used carb cleaner on a shop towel to remove any debris. I also learned that it is recommended that you use a light assembly oil on reassembly which I’ll detail later.

If you have to cut the olive off to start with an undamaged tube, you can get a new cutting ring, DMC has them (Bulk Ring- 106980 ). A new swivel nut is part number 106981 .

Interestingly, after the fitting was removed, I needed to put the adapter in a vice and use a 14mm wrench using a large amount of force to remove the -5 SAE 45° flare fitting on the OEM return line, so I seriously doubt this could have been removed in the car without damaging the hard line.

[DMC-81]

Here is the Frequency Valve removed. Stamped on it I see the Bosch part number: 0 280 150 300 and the DMC number is: 102395 . The high pressure line is 102400 and the low pressure line is integrated with the FV.



I applied WD-40 to the fitting and removed the high pressure line, being careful not to stress the FV, especially the plastic part. After removal, I found a fair amount of debris in the M12 high pressure fitting side of the frequency valve, so I sprayed carburetor cleaner on cotton swabs and cleared most of it out. You can only insert the swab end about a ½” in the hole as there is a fine screen at the bottom that you will want to be careful of. I then flushed the remaining debris out by gently spraying the cleaner in and dumping it out. Here is what I removed. I flushed 3 times until the swabs stayed clean and the screen was clear.



Here is what a clean FV fitting looks like, and the fine screen inside:


Old line removal:

I removed the old low pressure line by first cutting a 1" section of the rubber protective sheath off, which revealed the 8 mm plastic line:


^ I also trial fitted the new adapter which is shown.

Then, I scored the 8 mm plastic line with an Xacto knife being very careful not to scratch or otherwise damage the steel barb underneath. Then I cut the line just below the barb and peeled it away with needle nose pliers:



FV rejuvenated:

After the FV was cleaned and separated, I cleaned the plastic housing with mineral spirits and an old toothbrush, and decided to refresh the paint. I wet sanded it's metal case with 320 and then 1000 grit sandpaper and wiped it down with isopropyl alcohol. Then I brushed on 2 coats of Satin black rust inhibitor paint.



The paint turned out well as did the cleaning of the plastic part. I verified the condition of the 2 male connectors and they were in great shape. Now this expensive little part of the Lambda system is refreshed.

[DMC-81]

The low pressure hose is mostly braided SS but has a short piece of rubber hose. I see that you can now optionally send DeLoreanGo your FV and have it permanently fastened to the hose (like OEM). It's good to have choices. After some thought, I would still choose this configuration as it will make FV replacement or maintenance easier. However, this rubber hose needs to be fastened securely. I took some measurements of the width of the fuel injection clamp versus the length of the barb on the frequency valve to ensure that I positioned the clamp in the center of the barb. I figured that details matter here:



Same process for the other side:


I torqued the clamp to spec ( 13 in/lbs in this case), and used blue Loctite on the threads:




After a trial fit, I optionally chose to use a longer rubber piece of fuel injection hose (4 and 3/8 inches), to more smoothly route around to the braided Stainless Steel hose. When I shopped for the longer hose, I selected Gates Barricade GreenShield Fuel Injection rated for 225 psi - vastly overrated for this use, but it gave me peace of mind. I found the 1/4” (0.25 inch) diameter of this hose was very slightly smaller than the 7 mm (0.27 inch) hose that came with the kit. This meant a tighter fit on the 2 barbs.

Here is the low pressure Frequency valve hose all assembled, torqued and thread locked:



^ I also fastened the M12 60° cone inverted flare adapter to the FV. I applied a light assembly oil to the threads and the concave seal surface. The torque spec here is 7 - 15 ft/lbs. Considering I read that a leak free seal should be achieved with the minimum spec, I torqued it to 8 ft/lbs. That will allow more range to tighten if it should leak during testing.