Engine/Transmission (1998.5 - 2002) Leaky return line?

[ichoplin]

I've been chasing a fuel leak on my 02 with 82k miles. I think I've narrowed the leak down to the 't' at the rear of the motor where the return lines enters. I checked it for tightness yesterday and was able to get a couple of 1/4 turns on the horizontal nut. I drove it another 40 miles and checked it and it was still leaking. I degreased the area and had it all clean, then I drove it to try to really track this leak down. Again, I was lead to the return line. Using a stubby wrench, I was able to tighten it some more. This seemed odd, so I took the nut off the 'T' and found a rubber gasket at the orifice. It looks to me like this gasket should be cone shaped, like maybe it has torn and left part of itself in the 'T'.

Am I on the right track here? I don't have a service manual so I'm not sure if I'm thinking right or not.

Thanks,

Ian

 

[ichoplin]

Well, after a little more digging here I found a thread that mentions part #3905351 as the seal for this 'T'. I had called my local Cummins dealer and they couldn't see a seal in their catalog. I called back with the part # and they had some on hand.

Turns out this seal isn't cone shaped, mine was just damaged.

I've replaced the seal and am waiting for a test drive later this afternoon. I also went ahead and picked up the seals for that banjo bolt on the rear of the head. It's dry there now, but figured it couldn't hurt to have them and they don't take up much space.

Ian

 

[ichoplin]

I still have a leak at this T, though not as bad. I was able to tighten the return line a little. I suppose I'll replace the plastic connector next.
Ian

 

[ichoplin]

I ended up replacing the rubber line from the T to where it becomes steel and I still have the leak. It's definitely leaking at the horizontal leg of the T. Starting to think I may have some boogered threads or deformed hard line from the pump. I'll be picking up a new hard line and T today from my Cummins house. Hopefully this will fix this leak.
Anyone else had this happen? This all started after a 1400 mile trip pulling my fifth wheel. I 'm wondering if things got this way because of vibrations, or I guess it could be from age.
Ian

 

[Bill Johnson]

I also had this problem, it was the O rings in the T. I went to the dealer and bought three O rings about 16. 00 dollars. I have a 2000 2500 and it fixed it.

 

[ichoplin]

Yeah Bill, I replaced the O rings already. It seemed to have helped, as the underside of my truck isn't completely covered in diesel anymore, but it is still wet right there. I'll be replacing the T and hard line from the IP probably Sunday evening. We'll see how it goes.
Thanks,
Ian

 

[mwilson]

That style of fitting is something that Cummins has used for many years on coolant and air compressor lines. Sometimes the new rubber grommet simply will not fix a leak and you wind up changing the fitting.



I always figured that people over tightened the fitting trying to stop the leak and it stretched the threads, but maybe that isn't the case.



You could also have a tiny crack in that line that opens up under pressure or when it gets warm.



Either way you have parts enough on the way to cure it I'm sure.



Mike.

 

[gregdoerfler]

Mine had a pin hole leak in the line right behind the nut, but don't remember which one. It was like $100 for it from cummins.

 

[Hackamore]

Barbed brass tee

Use a brass tee and fuel hose to couple to steel lines. junk the original. Under ten bucks. .

 

[monkeyman]

when I p pumped my truck I replaced with braided line, one behind head is a pain to get to and change washers without loosing them, I used silicone and tacked it to head!
Rick

 

[ichoplin]

I think my leak may be fixed. When I took the T and return line off, I found the inside of the T was galled pretty good front the hard line. I suppose I contributed to it by tightening it up, but In my defense it was already leaking when I tightened it. Will know if it's fixed when I drive to work in the morning.

Thanks for all the help

Ian

 

[ichoplin]

No luck,still have the leak. Noticed fuel just under injector lines, but not much. I had thought fuel was blowing up there from the drain manifold area. Now I know that isn't the case. I guess I'll check the fuel lines after work and see if I have a loose one.

If one of these lines were loose, wouldn't the fuel come out under pressure? My engine compartment isn't soaked by any means. That's been my thinking and why I didn't consider the fuel lines first. Hopefully I've been thinking wrong.

What do you all think? Would fuel just drip from a loose line or would it spray out all over the place?

Thanks

Ian

 

[ichoplin]

My leak has stopped, for real this time. My #2 injector line was loose, barely! I mean I only turned it the nut maybe 1/16th and that was it. No more leak after 60 miles of driving.
Thanks for all the help,
Ian

 

[skillsaw]

Ian,
Did you actually see the fuel leaking at the #2 line (was it the head side of the line?)?
I'm chasing a few months of fuel hell here and have been digging through about 10 years of posts on this site.
Thanks and glad you nipped it!!
Erik

 

[ichoplin]

I didn't see fuel dripping from there, but it was obviously not dry. Fuel never accumulated anywhere but at the T fitting. I had just guessed that the wetness I was seeing under the inj lines was being blown there while driving, turns out I guessed wrong. That line was barely loose at all.
Good luck
Ian

 

[skillsaw]

thanks for reply.
... still hunting this down!!
-Erik