Leaking injectors

[Dieselnerd]

I've been reading about leaking injectors that fill the crankcase with diesel fuel on the Duramax site. Can the same thing happen to the new common rail Cummins engine? GM moved the injectors to the outside of the valve covers this year to avoid that problem. Are the injectors under the valve cover on the Cummins? I'm still trying to decide on a new truck and I like features of Dodge and GM and am looking for a "show stopper" on one or the other.

 

[rbattelle]

How can a direct injection diesel have injectors mounted outside the valve covers? Unless they've got a long fuel line extending from the injector to the cylinder, which would be quite strange.



Can the HPCR injectors fill the crankcase with oil? Yes, but then so can any injector that gets stuck open or leaks. I don't recall more than 1 or 2 people on this board who had their crankcase filled with diesel with these engines.



You must be aware, however, that any common-rail injector system will be, by it's nature, much more sensitive to contaminant-induced wear than a jerk-pump arrangement. These type of injectors do not respond well to wear at the needle and seat, which are positioned right in the cylinder. That's why so many Duramax guys are running 2-micron fuel filters (something I want to set up on my truck eventually).



Overall, the Cummins HPCR has seen FAR fewer injector failures than the early D-Max's have. However, the fleet is still rather young. Keep in mind that the Cummins injectors are of the same principle of operation as the D-Max, but are of different design... one that has been in use in Europe and the 6BTA for over 2 years now with a good record (as far as I know).



I don't think injectors or fuel system are a "show stopper" for the choice between the GM and the Dodge. However, this thread contains a couple photos that were show-stoppers for me!

 

[rbattelle]

One other thing... I live not more than 10 minutes from Morraine, OH, where the D-Max is built. You'd think there would be lots of D-Max trucks running around this area, but there aren't. Mostly Fords in the city areas and Dodge's in the rural areas. I have always found this quite interesting.

 

[ata]

Boy I guess I've got something wrong here. My Injector lines are not under the Valve Cover on my 97 Dodge Cummin's. For that matter there on the outside of all the Cummin's up to 98. 5 with long Injector Lines and they are Direct Injected. There are lots of Direct Injected Diesels with the Injector lines on the out side of the Valve Covers.

 

[rbattelle]

Originally posted by ata

Boy I guess I've got something wrong here. My Injector lines are not under the Valve Cover on my 97 Dodge Cummin's. For that matter there on the outside of all the Cummin's up to 98. 5 with long Injector Lines and they are Direct Injected. There are lots of Direct Injected Diesels with the Injector lines on the out side of the Valve Covers.

Hmmm... as I read Dieselnerd's post I see it says "GM moved the injectors to the outside of the valve covers... ".



Obviously, he was talking about the fuel lines, and "injectors" is some sort of code for "fuel lines". How could I have been so stupid as to not realize the obvious? Thank you, ata, for pointing out what a moron I am and how amazingly brilliant you are. I humbly bow before your massive intellect.



(I'm sorry, I'm not normally such a smarta$$ but something about the condescending nature of that post bothered me this morning).

 

[Dieselnerd]

rbattelle, the latest Duramax actually have the valve covers cut out around the injectors. It looks a little strange and makes for a longer sealing surface but they are outside the covers. Thanks for the interesting and informative post.



The Cummins strength is not in question but I always get a 4x4 and I don't like the lack of front axle disconnect on the Dodge. I've driven both and the Chevy really feels better to me with the independent front end. I also like the Allison 5 speed auto. I've been hoping for a 5 speed auto in the Dodge but other than rumors it doesn't seem to be happening. I like the better turning radius on the Dodge and the 4 door Dodge fits my garage. The 4 door Chevy won't fit so I am limited to the extended cab. So far they seem to balance out although I prefer to stay with the Cummins.

 

[rbattelle]

Originally posted by Dieselnerd

rbattelle, the latest Duramax actually have the valve covers cut out around the injectors.

That is very interesting, and indeed I think it would look rather strange. Hopefully GM has seals that are good enough around those injectors. I wonder if that design makes changing injectors easier?



For me, I like simplicity and you can't beat the Cummins for that. But I also like 4 doors (whether they're "full size" or not).



Do the Chevy 4x4s have front axle disconnect? If they do, I hope it's not that thermal system they used back in the 80s and 90s.

 

[Dieselnerd]

rbattelle:

The Chevy does have a disconnect. I'm not sure how it operates but I guess it would be similar to my 2002 Chevy Trailblazer which is motor driven and has almost instant engagement. The Chevy brochure has pictures of the new valve covers and even states that the injectors are easily replaced now and the new design prevents oil contamination if they leak. That statement is why I asked the question on the TDR website about leaks. It won't prevent oil contamination if the injector sticks open but my understanding is that most GM injectors were leaking inside the valve covers. A friend of mine has last years Duramax and he was even told by the dealer to watch his oil level and if it started to rise, bring it in right away.