i recently found oil in my crankcase after getting an oil analysis i took it to a dealer believing it would be an injector problem i got a call from the dealer saying my injectors are fine but i have a leaky return line and return line seals that are in the heads and that is what is causing my problem they quoted me 4300 to fix the problem which i thought was way too much so i brought the truck home dealer charged me 200 dollars to tell me that before i brought it home i popped the hood to see if anything had been done as i know my truck very well and purposely took it in with the motor a little dusty so i could tell if they touched or not so i told the service manager hey man my truck wasnt touched under the hood what did your tech do he told me they could tell by pressure test. my questions are would a leaky return line get fuel in the crankcase?can they tell my exact problem just by pressure test? or are these guys fool of it?

A leaky return line can cause this


that price is absolutely insane

is it a hard job to do it myself where can i find the parts

is it a hard job to do it myself where can i find the parts

Not a hard job, I just did the whole injector swap because of the same issue. You'll want to thoroughly inspect the return lines, as well as the injectors where the return line connects. Mine had corrosion on both the inlet and outlet on the injectors. Pensacola Diesel sells a complete kit for around $1350 (includes 8 remanufactured injectors, seals, gaskets, etc.) Everything except the thermostat gasket

GM books the labor at something like 12-13 hours, it took me at least that long to do it but I was slow and meticulous in the process.

If you want to try JUST replacing the return line seals, you could for a lot less money but you're still going to incur a lot of time pulling down the engine to get to them. Upper and lower valve covers have to come off to get to them all. To me, not worth the labor to only do half the job. My injectors were not leaking at the tips, just at the inlet/outlet fuel lines.

There's a sticky at the top of this forum on how to....

I had a leaking return line gasket after I replaced all 8 injectors. I was able to find my leak with possibly a cheating, crude, and redneck method but it worked for me.

Disconnect the return line quick disconnect (drivers side in front of the glow plug controller). hose clamp a piece of 3/8 vinyl tubing to the hard line and run compressed air, co2, nitrogen, your own breath, whatever you have got into this line. I found that this return line would hold no pressure. I popped the breather lines off each valve cover. Vapor would escape out from the passenger side each time I pressurized the line.

This allowed me to at least figure out which bank was leaking. I used the same method to isolate the leaking gasket once I'd torn down that side. Hope this was clear enough.

One more thing. I'd really doubt that your return lines would just start leaking. I suppose anything is possible but sounds like injectors to me.

I had a leaking return line gasket after I replaced all 8 injectors. I was able to find my leak with possibly a cheating, crude, and redneck method but it worked for me.

Disconnect the return line quick disconnect (drivers side in front of the glow plug controller). hose clamp a piece of 3/8 vinyl tubing to the hard line and run compressed air, co2, nitrogen, your own breath, whatever you have got into this line. I found that this return line would hold no pressure. I popped the breather lines off each valve cover. Vapor would escape out from the passenger side each time I pressurized the line.

This allowed me to at least figure out which bank was leaking. I used the same method to isolate the leaking gasket once I'd torn down that side. Hope this was clear enough.

One more thing. I'd really doubt that your return lines would just start leaking. I suppose anything is possible but sounds like injectors to me.

Thats a good idea

I agree returns usally don't just start leaking

think i should try another dealer? as a few people have told me they suspect it be injector problems that returns don't just start to leak. if i do end up doing the work myself where can i find the parts for the return lline?

the only leakers i've seen were where some clown forgot a banjo gasket during injectors....

and that price is insane,even for injectors AND return lines...go elsewhere

The dealer has the seals

i recently found oil in my crankcase

This is good thing... trust me! :):):)

On a more serious note, in my opinion you would be wise to take it to another dealer and get a second opinion - preferably without cluing them into the fact that they are doing so.

I have a very hard time believing that a return line, or a high pressure line would just begin to leak given the way in which they are sealed. Sounds like a classic case of injector failure.

$4300 should be nearly enough to complete an entire injector job even if paying GM retail of $350 per reman'd injector. I was quoted 4500-5000 by my GM dealer, and two other respected diesel repair shops - both Bosch authorized dealers - to do the entire job. I opted to do the job myself, and bought my injectors, gaskets, and seals from gmpartsdirect.com. Here is a recent post including my price findings:

http://www.dieselplace.com/forum/showpost.php?p=3355041&postcount=6

Also, I learned about partszoneonline after I made my purchase and they may have been just a few bucks cheaper than gmpartsdirect.com.

You could save a few hundred more if you choose to go with pensacoladiesel.com, or realdiesel.com, but you have to comfortable with the knowledge the Bosch has not authorized anyone to properly test the injector bodies and rebuild these injectors, nor do they sell the parts to do so. I wasn't willing to risk it to save $400!

I got the same song and dance last year with my truck. After the return lines were replaced on my dime I still had oil in my crank case. Took it back to same dealer but this time a different tech looked at it and said it was the injectors. Replaced under warranty but it took me a month to get a refund

ha ha ha my bad i ment i recently found diesel in my oil

These return-line diagnosis are a cop-out for the most part...IF you just had injector work and are getting fuel in oil,then yes,I imagine a fitting is loose or whatever...if the valve cover has never (or in some time) been off,they did not just begin leaking...its a very low pressure line.

Loading up to do my injectors this weekend....