Greetings and Salutations!

Once again I am in need of some expert help as I am still pretty ignorant when it comes to LS motors. I have a 2002 Z06 with an LS2 motor in it (@402ci) with approximately 6000 miles on the motor. Sort block was built by SDPC. Just bought the car a few months ago from aa forum member and it has an oil leak somewhere in the back of the motor. I removed the driveline, clutch and flywheel to investigate, and anticipated that it was most likely the rear main seal. Once I got everythign apart, this what I found (see pics below). The pilot bearing came out with my finger (basically just fell out of the back of the crank) As you can see in the pics, it appears the rear main seal is NOT leaking. It almost looks like the oil is coming from the center of the crank. I have done as much research as I can, and I understand that there is a plug that is pressed into the back of the crank. On my car it appears that this plug is indeed installed. What could be leaking?? (the leak is bad enough to cause drips on my garage floor after a drive, the whole underside of the car is basically coated with oil). Can oil get passed that pressed in plug in the back of the crank?? Can I replace this plug with the engine in the car?? If so how would I do that?? Proper procedure?? I do not believe the oil was coming from the flywheel bolts, nor does appear to be coming from the rear main seal carrier (housing) gasket. I am at a loss. It is nothing from the top of the motor, all of the oil is confined to inside the bell housing.

Obviously I want to fix this leak since it is such a PITA to get to the back of the motor with having to remoave the entire driveline. Thanks in advance for any assistance you all can offer! You all are the best!!

 

ttt

 

Looks like, from the pic the leak is coming from higher up. Notice the right side of the head, where is all that oil streaming from?That amount would obviously seep into the rear of the block and pilot housing. Some of the cars here that have done the "oil catch can" mod can be over restricted if the setup isnt correct. This happened to me a couple of years ago, I installed the bypass with clear evaporator unit etc, but left the filter in place. This created too much pressure and blew the rear seal. I now just have the glass jar as the "catch" can. Sorry got off subject, still think you might check the back of the intake and right side head.

 

Thanks for insight racetchr. I am stumped. The intake is off. The back side off the right head above the bellhousing is dry. The top side of the bellhousing is dry. All of the oil (wetness) is inside the bellhousing.

You mentioned catch can pressure build up. On my car when I bought it, it had a small breather filter where the oil fill cap went, and the right valve cover vent line was capped off. PVC from the valley to the TB is in tact and as stock. I dont like the breather as it really dirty's up the engine compartment, so I am going to remove it, put the stock oil cap back on and run the right valve cover vent line to the air bridge as stock. I am not sure the way it was with the breather and plugged vent line would cause any issues, but maybe??

I see what you are looking at in my pics with the right head being so wet. My initial thought was if indeed oil was coming from the center of the crank and getting on the back of the flywhee then the flywheel was slinging it to the right and up, as that is the proper rotation direction, adn then the wet oil is simply running down the back of the motor. The left side is as you can see very dry.

In my second pic you actually see a small puddle of oil sitting in the bottom of the crank recess. I tell ya, I am as confused as a cat at a dog park.

 

Well there is another possibility, is your clutch slave leaking fluid? dirty fluid could look like oil. If it is dry overhead and no clutch probs, I'm stumped too.

 

The thing that has me concerned is the pilot bearing almost fell out. When I put the pilot bearing into my new LS2 I had to hammer it in with a socket on the outside race. What did the bearing look like? Was it in good condition or messed up? I'm wondering if it was installed improperly or the pilot bearing that was in there was a replacement. If the original was replaced with the one that you removed with your finger and they removed it the 'old-fashioned' way, that could be your problem. You probably know the old trick where you pack behind the bearing with grease then put a rod the size of the input shaft in and hit it with a hammer to pop the bearing out and remove it hydraulically? That doesn't work on an LS1 crank and can destroy the seal in the rear crank plug.

It looks to me like the rear crank plug has been compromised although it's hard to tell from the pictures. If you clean it all out with brake cleaner or something will the 'puddle' return or do you have to pressurize the oil system for it to show a leak?

Although I've never done it, I'm sure you could get another rear crank plug, remove that one and replace. What has me concerned is the pilot bearing 'falling out'. If you get another new pilot bearing and go to fit it, does it fit really tight like you'd have to bang on it for it to go in?

 

Pilot bearing just "falling out" is not good. Could mean the bore is oversize due to damage during the last PB change. Maybe PO used the wrong method to extract the bearing and the bore and crank plug seal are damaged. The plug looks a little suspect in the second shot.

 

Thanks for the response ArKay99. The pilot bearing that came out of the car is a roller style bearing. As far I as know it was installed in the brand new motor approximately 6000 miles ago, when the motor was installed in the car and the clutch was replaced at that time as well. The bearing itself appears to be in decent condition. There is some small gouge(sp??) markes on the outer casing, almost as if the bearing was loose and spun in the crank.

I just pulled the clutch and flywheel today, so I am not yet sure if the oil will puddle over nite or if it requires oil pressure.

I just found this thread - http://forums.corvetteforum.com/show...=rear+oil+leak - which appears to mimic what I have found on my car almost to a tee. My clutch was dry though, all the oil was on the backside of the flywheel. Based on this thread, I am leaning more and more towards the crank plug leaking. Gotta figure out how to remove the old one.

 

The pilot bearing in the LS1 is a roller type. i.e. you can see the rollers on the inside race. The LS2 is much larger and fits to the larger diameter opening at the very rear of the crank and it has a solid race inner face. I have one in my hand. One thing to check before you buy another bearing would be the roundness of the bearing surface in the crank, and also it's size. It should be a thousandth or 2 smaller than the bearing so it goes in tight. I just checked my manual and it doesn't give any typical or service limit tolerances for this part. Also, as far as the crankplug, all it says is that a loose or damaged oil gallery plug must be replaced. I have a cross section drawing showing the plug and pilot bearing install depths. If you want, pm me and I can scan it and email to you.

 

 

Well, one day later and I am still at a loss as to what is leaking. There was not any additional "puddling" of oil over nite in the center of the crank where the plug is. I examined teh pilot bearing again, and I can slide it into the back of the crank with my pinky finger, I know that is not the best thing. It doenst rock around in the back of the crank, but I know it should be at least a press in fit. I will get a new pilot bearing and see if it fits any better. I can at least locktite in place if I have too. The plug it not loose, at not loose to my finger. But I am wondering if the bore in the crank is just a hair too big, then maybe that plug will only leak under pressure (i.e. the engine running). The car would only drip after a drive. It is an aftermarket Eagle forged crank. Wouldnt be the first time I saw an aftermarket part that was ever so slightly off. I guess I will replace the crank plug and use some red locktite to help seal the surfaces and replace the rear main seal just to be sure. It is the only thing I know to do at this point.

I want to thank those that have replied, you have been most helpful!

 

You cannnot "loctite" the pilot bearing brother....that's not going to hold it in place

 

JB Weld then??

Serioulsy, you dont think it would work? There is less than .002 difference in diameter, and that is with the bearing I have. I dont have a new bearing in my possession yet, so I cant measure that difference.

 

Absolutely not. The pilot bearing is made to be a press fit, not a slip fit. You need to determine what the discrepancy is. I remember some time ago, SLP was shipping 402 shortblocks with the wrong bore in the crank,consequently, the pilot bearing was loose. You should have to hammer the bearing in. Just wait, collect all the measurements, and do the job right.

 

Ugh. You're killing me! I have a new pilot bearing coming. If it doesnt fit any better, then I am as hosed as hosed can be. I am not taking the motor out of the car to replace a crankshaft that only has 6000 miles on it.

 

You run the chance that the bond will break and those superhard chunks will find thier way into the new pilot bearing. Don't want to be there for that. Also, if the bearing was loose, the opening it fits into behind the plug could be excessively out of round. If that's the case your input shaft is going to wobble and give you vibration on top of what is happening. I seriously hope it is just a messed up bearing.

 

Relax. .002 is a little big for a press fit. Just do the following with a caliper:

1) Measure the diameter of the bore in the crank.
2) Measure the diameter of the pilot bearing you removed.
3) Measure the diameter of the new pilot bearing.

I'm interested to see what the disparity is. Don't even think in terms of pulling the motor. If worse came to worse, you could get a custom bearing size made, but I doubt it will come to that.

No sense in getting your underwear all bunched up until you have collected all the necessary data.

 

Thanks for all the help fellas. I sincerely appreciate it. Sorry if my last post sounded like I was in panic mode. Not quite to panic mode yet. I too am very interested in seeing what the difference in OD of the existing bearing and new bearing is.

 

I hope the new bushing will fit your crankshaft properly and that it was an oversight on somebody elses part.

The only bad thing that I can think of out of this whole deal is that your talking about a Chinese made crankshaft, I know there are a lot of people that are using these with good results but yours is also not the first one that I have heard of that is faulty.

BTW, I don't think SDPC actually builds motors, they are a GM dealership and buy these things for resale.

 

So Eagle is a Chinese reject huh?? Never knew that. SDPC does build motors. They are indeed a huge GM Crate motor reseller, but they do custom stuff as well.

New pilot bearing should be here in a few days (nobody around town had one in stock). I too hope I have to beat the hell out if to get it in LOL!

I still need to figure out how to get the rear crank plug out.