Hello, newbie to this forum. I hope this is the right place to post this thread if not im sure an administrator will kindly direct me to the right place. Ok hear is whats going on. My boss just bought me a 2001 gmc with the LB7. the truck is super clean but has a few issues. I need advice. first thing Ive got to do is fix this monstrous oil leak. this is what I know from looking. I suspect the rear main. The oil is in the bellhousing and drips from the little inspection cover. its everywhere. I don't find much at all on either side of the block up past the oil pan. the block is really clean the farther up you look. no oil at all up towards the heads. like I say I suspect the rear main. I will install it myself. Has anyone removed/installed without using the ultra high priced tool. I refuse to buy that tool so thats that. If i cant find one to borrow I need suggestions on removal install. Im a good mechanic and have installed front and rear seals on detroit and cat engines so i do have experience. Ive used the tools and not used the tools. none have ever failed. I will pull the allison and t-case this weekend after I rule out the turbo oil lines. Thanks for any help.
LB7 leaking like a Detroit..
- Thread starter tommywalton1974
- Start date
I thought the same thing, now I own the "high dollar" tool. It went in easy and felt great but leaked from the second start. Buy the tool, it sets the depth correctly!
thanks guys. I put my foot in my mouth for sure. After lying under the rig for 10 minutes getting my plan together on trans/t-case removal, drive shafts, cross members, oil lines, linkages, bolts, busted knuckles, etc.. I will not be going back a second time and re-doing it. The dealership wants 10 hrs. labor at who knows what cost to do it and honestly I don't trust anyone other than myself to work on anything of mine period. (except machining, rotating assemblies) These guys around here are a joke. Im going to locate a tool or person with a tool locally and use it or have them stop by and watch me install it. whatever works. any tips or anything you guys have that have been where im going is appreciated.
Before you rule anything out just make 100% sure it's not coming out of the crank case vent tube on the passenger side toward the back of the block, if so then that's bad injectors over flowing the crank case with diesel. When mine went out I thought the same thing as you til I really went to looking. Not trying to insult your mechanical savvy, just my two cents.
If my memory serves me correctly it's behind the front wheel so I'd consider it towards the back of the block, but feel free to correct me if I'm wrong, it's been awhile since I've been under mine
Last edited:
you may want to double check the valley is dry also . I had a turbo drain leaking and initial thought was a rear main also . the valley has a hole near the rear that lets anything leaking drain down in the back .
Well the main reason I think it's the rear main is because oil drips from the bellhousing. But I will double check because ANYTHING is possible. Also oil is looking as it should, reasonably thick, black, and no diesel smell. Also oil level is not increasing. It drops pretty fast from the dipstick. I mean if an injector was dumping fuel in the crankcase the level should rise some? Or stay close to the same? How does it get in the case anyway? Does oil cool the injectors and it get around a seal or injector cup? I'm going to run it and watch an see if oil drips out of the hole in the bottom o the bellhousing. If it does that's cut and dry to me. Thanks
Yes if the injectors were out the oil level would be way up and would have a diesel smell. I'm not exactly sure of the mechanics of how the diesel makes it's way into the crank case but I know for a fact that it's the end result when the body of an injector cracks.