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Thread: Replacing the Frequency Valve and Return hoses

  1. #1
    Senior Member DMC-81's Avatar
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    Replacing the Frequency Valve and Return hoses

    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...
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  2. #2
    Senior Member Parzival's Avatar
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    let me know when you plan to do this, I'll be happy to come lend a hand!

  3. #3
    Senior Member DMC-81's Avatar
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    Quote Originally Posted by Parzival View Post
    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.

    ----------
    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.

    ----------

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


    ----------

    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.
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  4. #4
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    Quote Originally Posted by DMC-81 View Post
    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


    Sept. 81, auto, black interior

  5. #5
    Senior Member DMC-81's Avatar
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    Return Hose Removal continued

    Quote Originally Posted by Jonathan View Post
    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!

    -------------------
    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.
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  6. #6
    Senior Member DMC-81's Avatar
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    Frequency Valve

    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 ˝” 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.

    Last edited by DMC-81; 01-30-2019 at 08:02 PM.
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  7. #7
    Senior Member DMC-81's Avatar
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    Assembling the New Low Pressure hose:

    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.
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  8. #8
    Member cis6409's Avatar
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    Amazing detail, top drawer work there!.
    have to do this job for my car to complete my braided lines upgrade.. Invaluable advice !
    Much appreciated

    Shane
    only from the past can we choose the correct path for the future...

  9. #9
    Senior Member DMC-81's Avatar
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    Quote Originally Posted by cis6409 View Post
    Amazing detail, top drawer work there!.
    have to do this job for my car to complete my braided lines upgrade.. Invaluable advice !
    Much appreciated

    Shane
    Thanks Shane! I am glad it is helpful.

    ----------

    FV Hoses Installed:

    Below is the routing I used for the hoses on the frequency valve. I decided to direct the high pressure hose on the upper side of the FV because the lower side (like the original routing) was right above the exhaust manifold.

    Here are the Torque Spec ranges I researched and found, the one I used, and why. Standard disclaimer: you will want to verify these specs for your situation, especially if your hoses are different.

    As mentioned previously, I read that one should lube the male threads and the concave seal surface with light assembly oil. Of course, a lubricated fastener needs a lower torque value, also that the minimum torque spec should deliver a leak free seal, so I took these 2 factors in to the selection of the spec used.

    1. Adapter- Hose Side: AN-3, Thread: 3/8"-24, Flare: 37°, steel fitting (lubricated):
    Spec: 95-140 in/lbs or 7.91-11.66 ft/lbs. Mid point: 117.5 in/lbs, or 9.79 ft/lbs.
    Torque used: 95 inch/pounds, or 7.91 ft/lbs

    2. Repeated from above- Adapter- FV Side: M12 60° cone inverted flare steel fitting (lubricated).
    Spec: 7-15 ft/lbs, Mid Point 11 ft/lbs
    Torque used: 8 ft/lbs



    Hose Connections to Distributor:

    Here are the new hoses routed to the fuel distributor. I made sure that there wasn't any contact with other hoses, clamps, etc. which will prevent chafing.
    Torque Specs:
    Frequency Valve Hose - High Pressure Side:
    Metric Banjo hollow bolt to Fuel Distributor: Size: M8 7 ft/lbs. (Uses a 12 mm socket)
    Frequency Valve Hose - Low Pressure Side:
    Metric Banjo hollow bolt to Fuel Distributor: Size: M12.
    12 ft/lbs (Uses a 19 mm socket, it is shared with the return hose).



    Return Hose Installation:

    These are the Torque specs I found and the one I used:
    1. Aluminum banjo bolt: Size AN-4 (Thread: 7/16"-20, Flare: 37° lubricated)
    Spec: 100-140 in/lbs , 8.3-11.6 ft/lbs
    Torque used: 100 inch pounds

    2. Adapter- Return hose side: Metric tube compression male fitting for an 8mm tube, thread: M14 , steel fitting, lubricated.
    Spec: 15-26 lb/ft.
    Torque used: 15 lb/ft
    I used a 14mm wrench on the nipple, and a 17mm wrench on the swivel nut and used the one hand technique to tighten the fitting to the minimum spec.

    3. Adapter- Hard line side: Metric tube compression male fitting for an 8mm tube, thread: M14 , steel fitting, lubricated.
    Spec: 15-26 lb/ft.
    Torque used: 15 lb/ft
    This was the same as the other side. As before, I used a 14mm wrench on the nipple, and a 17mm wrench on the nut and used the one hand technique to tighten the fitting to the minimum spec.

    NOTE: This is the beauty of the braided Stainless Steel Delorean Go return hose. It has an adapter that directly attaches to the 8 mm hard line using the existing cutting ring / "olive" (DMC 106980 ) and M14 swivel nut (DMC 106981). Therefore it replaces the OEM adapter (106994). No need to cut the hard line. Brilliant!!





    Conclusion:

    Pictured is the final result with everything re-installed. Everything matches nicely. You may notice that I ended up rotating the return line rigid 90° elbow back a bit as it was not horizontal and the crimp was just making contact with the lower engine cover. For testing, I primed the fuel system 4 to 5 times and waited. No immediate leaks. Then, I repeated the priming and started the engine.... SUCCESS! No leaks or weeping. Also, the Frequency Valve seems to have liked the cleaning as it is more audibly makes the FV sound than before.

    The picture is with the engine running:


    I would also like to give a shout out to Arran and DeLoreanGo for the excellent customer service.
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  10. #10
    Senior Member DMC-81's Avatar
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    Appendix: Heat Shrinking the Hoses:

    One other thing, and as mentioned, I bought these hoses previously before DeLoreanGo began offering pre-wrapped hoses. So I wrapped the return hose myself and wanted to show you how easy it is:

    I found an appropriate size black semi-rigid plastic heat shrink tube with integrated glue for the job. It was 3/4 inches which fit over the swivel nut and reduces down to half it's diameter, 3/8 inches, which is the OD of the hose.



    Cut a length slightly longer than the area you want to cover.



    Then use a heat gun on a low setting and start at one end. Use one hand to hold the hose and at the same time the other end of the tube. Use the other hand to wave the gun close, but not touching the HS tube. Only do 1-2 inches at a time, going around the circumference of the hose.
    Watch the un-shrunk end to ensure it doesn't shrink in length or get twisted while soft. Mine tended to want to shrink lengthwise so I gently tugged the HS to stretch the soft portion and maintain the original length. Don't overdo the stretching.

    Here is the heat shrinking in process :
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

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