Jump to content

Return fuel line leak on a Cummins N14


Recommended Posts

   Yesterday I was working to fix a airline leak on the brake valve on the firewall. We have a Volvo 610.

   I noticed a very small leak on the fuel return line where it hooks to the check valve base, then heads towards the fuel tanks. So the fuel return line comes out of the rear of the head. Then comes around the side of the heads, with a 90 turn to the check valve base. It is a new  line installed about 4 years ago. About two years ago I could smell a faint diesel smell occasionally. But could not find a leak. But now it is there. It was real small, sorta just damp. Since I could not tighten it, i loosened it and retightened it.

  Now it is leaking more fuel.

  So I am curious if I could cut the line, flare the end an put a metal brake line in to make a better connect. Or use a dot compression fitting to extend to line. I have one with me.


  Thanks in advance,   Vern

 we sat in New Mexico all winter. Wanted to leave by Friday at the last.

Edited by Wrknrvr
Link to comment
Share on other sites

It's a different flare angle than a brake line. JIC, if I remember right. You might be able to access it from under the dash, if Volvo blessed you with a removable doghouse cover under there. If not, try a basin wrench. A good service truck (Jeep) should carry a basin wrench.

Link to comment
Share on other sites

 It looks like Cummins has at least two of them sitting in Albuquerque New Mexico.

   So will order one to be shipped today.

  Cummins person I talked to could not say if they were jic. Or brake line flares.

  I believe we can still get out of here by Friday.


  Thanks Darryl for helping.



Link to comment
Share on other sites

  Yesterday I ordered a new return fuel line from Cummins. There were at least two sitting in Albuquerque New Mexico. We are about 2 hours or so south of there.

   With the part and overnight shipping the cost was less than 85 bucks. So ok I still have stuff to do. So I ordered it overnight delivery. Called too late last night to get a tracking number. Call this am. Got the number.

  The part when I first looked this am, is now sitting in Memphis Tn. What the bad word that is.

 So later this am it is now sitting in El Paso Tx. Supposed to be delivered by 4:30 today.


   Hope I get it, although that is ,well it is what it is.

  Still got packing to do. 

Link to comment
Share on other sites

    Well the part arrived arrived at 2:47 pm. I made sure both female ends were clean where this fuel line went into. Installed the line. Tightened it at what I thought would work. Both ends weeps just a small amount. So I tightened then just a little more. Still weeping at both ends. Tightened to the max that I wanted on the end on the return line. Tired and irritated. Start the truck again and the drain side that started this subject is not leaking. I quit for the day.

   Yesterday I tried to tighten the fitting on the rear of the head. Still leaking just enough to be irritated. The line is steel with steel nuts. Both fittings where the steel lies go are brass. So it could be easy to damage the brass fittings.

   So I had contacted two people on the forum and had some good thoughts. Thinking about what I should do.


   Over the years of getting parts at a small privately owned diesel shop in Montana I thought well I will call and se if they could give me some thoughts on said subject. It went so so talking to the shop supervisor. I could tell would not say anything out of the normal fixes. Like farmers or well drillers do in desperation 

  So I asked how the old owners wife is doing. She is in her third fight with cancer. He said she doing ok. So I asked about Willy, the old owner. He sold the business a year ago as his wife was really in a serious situation. They use to spend the winters in Yuma as they are rv’s also.


   He said do you want to talk to him, he is sitting right here. Yes I said. So I explained to him what my problem is. He can remember what parts I bought from him years before. When I was doing mobile rv repair near Glacier National Park, I would send him business that I could not do in the field.

   He said you need Cummins part number 131026. It is a o ring, Since this is on the return line, it dies not have high pressure. So I said I have o rings that will fit. I took the line off the rear of the head, installed a o ring.



   Took it for a short ride, some up some steep hills.        Nooooooo leakyyyyy. At least so far. So I did put just a small amount of goop glue on the nut and fitting to keep that flare nut from backing off.

  So i will take the truck on a ride today to test it more before we put the doghouse back on.

   Thanks to the members that I did contact with pms.




   Wiley said to put his cell number in my phone. I can call him if I really need to.


Link to comment
Share on other sites

So, where the o-ring goes is not a flared fitting?  I was under the impression both ends were flared.

For non-flared fittings, Loc-Tite makes a line of sealants that are quite good. Some of them are available only in John Deere stores.

Upon re-reading your original post, I see where I misunderstood you.

Link to comment
Share on other sites

Posted (edited)

woPoKuEl.jpg is a flared fitting. The tubing is a double flare..


  in my collection of used brass fittings I found a female flare fitting that had a small o ring in it. And no I did not put that one in there. I have cheated with o’ring fixes on other plumbing stuff before. Looking at the physical parts, it sure looks like a o ring would do the trick. 


   I will get a picture of the old flare end today and post it. The edge of the double flare is rounded so as it will not cut the o’ring

Edited by Wrknrvr
Link to comment
Share on other sites

This shows the smooth rounded end of a double flare on a tube. So a o’ring should work good. I did not tighten it real tight. As being cautious about damaging the o’ring.


  Well I took it for a ride to Walmart and back yesterday afternoon. I smelled fuel when I got out. Went shopping and back home. Got out smelling fuel again.

  My nose must be on high alert.   I checked this am and no leaks.     I think wind that was blowing pushed the exhaust fumes in my direction, as it was blowing towards me both times I got out.


   I did check this am and no leaks.



Link to comment
Share on other sites

  • 2 weeks later...
  • 4 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...