racecar

I put this L92 block together with the LS6 top end last year and it started leaking oil down the bellhousing, and onto the starter. The oil pressure sensor on the valley cover was leaking around the gasket, I fixed that. There were still leaks down around the starter, so I replaced the pan gasket with the new part number gasket for a 2010 Camaro. That fit the block better and it works with my LS6 oil pan. I had the bottom of the bellhousing off, it is clean inside. Back of the block is clean.

It still leaks, so I replaced the valve covers with new ones and new gaskets because they were leaking. Now, It still leaks onto the bellhousing I see oil on the bottom of the starter, and on the starter bolts, I think it is coming from above. The crank sensor looks clean. Maybe I should take the main cap side bolts out and apply more silicone???
Anybody have leaks with L92 blocks? What am I missing here. I'm going to pull the intake one more time to see if the pressure sender or anything else is leaking on top, what else could it be?? It's not the rear main seal because I can see the front of the flywheel is clean.

racer7088

I'd make sure the block or crankcase is well vented. Maybe you are getting some pressure and it is causing the leaks.

rsz288

Maybe something different but there is a TSB re porous rear faces of LS blocks.

1lejohn

iTrader: (9)

No leaks on mine yet. Strill running regular oil not syn.

racecar

Could the bell housing bolt holes in the block be drilled deep enough that oil is coming out around the threads? That's where it looks like it is coming from, bellhousing bolts right above the starter. Is that possible?

1lejohn

iTrader: (9)

I don't think they are near the oil pass. Some of them are not blind holes any way. Rear main seal , and the oil is being slung around. The oil pan level switch? It is located on the starter side on my car.

LS1 BU

iTrader: (13)

No leaks with mine.

racecar

Oil level sensor and dipstick tube are clean. I'm vented back into the intake. I even plugged a T into the breather line and went for a cruise with a vac gauge. It had good vacuume at idle and mid, even had 1 pound at WOT.

RSZ what is "TSB re porous rear faces of LS blocks." What is TSB?

1quickirocz

99% sure that performing this TSB will solve your problem.

#05-06-01-034K: 5.3L, 5.7L, 6.0L, 6.2L, 7.0L-Engine Oil Leak at Rear Cover Assembly Area (Engine Block Porosity RTV Repair Procedure) - (Apr 8, 2010)


search that number and you can probably find the entire procedure online somewhere. I dont think it will allow me to put it all on here. basically you use RTV and put it all over the rear cover surface on the block then scrape it away and it fills in the small pours in the block that the oil seaps through. very very common problem with all the later allum block gen IV engines and even some LS1s.

1quickirocz

Subject: 5.3L, 5.7L, 6.0L, 6.2L, 7.0L - Engine Oil Leak at Rear Cover Assembly Area (Engine Block Porosity RTV Repair Procedure)


Models: 2004-2007 Buick Rainier

2008-2009 Buick LaCrosse Super, Allure Super (Canada Only)

2005-2010 Cadillac CTS-V

2007-2010 Cadillac Escalade, Escalade ESV, Escalade EXT

2003-2009 Chevrolet TrailBlazer

2003-2010 Chevrolet Corvette

2004-2006 Chevrolet SSR

2005-2010 Chevrolet Silverado, Silverado SS

2006-2007 Chevrolet Monte Carlo SS

2006-2009 Chevrolet TrailBlazer SS, Impala SS

2007-2010 Chevrolet Avalanche, Suburban, Tahoe

2009-2010 Chevrolet Colorado Pickup

2010 Chevrolet Camaro

2003-2009 GMC Envoy

2003-2010 GMC Sierra

2004-2005 GMC Envoy XUV

2007-2010 GMC Yukon XL, Yukon Denali, Yukon XL Denali

2009-2010 GMC Canyon

2004-2006 Pontiac GTO

2005-2008 Pontiac Grand Prix GXP

2008-2009 Pontiac G8 GT

2009 Pontiac G8 GXP

2005-2009 Saab 9-7X 5.3i

2008-2009 Saab 9-7X Aero

2003-2010 HUMMER H2

2006-2010 HUMMER H3

with 5.3L, 5.7L, 6.0L, 6.2L, 7.0L VORTEC™ GEN III or GEN IV V8 Engine (All Aluminum Block) (RPOs L33, LC9, LH6, LH8, LH9, LM4, LS4, LS1, LS6, L76, L77, LFA, LZ1, LS2, L92, L94, L99, L9H, LS3, LS9, LSA, LS7)




--------------------------------------------------------------------------------

This bulletin is being revised to add labor time information for the Colorado and Canyon. Please discard Corporate Bulletin Number 05-06-01-034J (Section 06 - Engine/Propulsion System).


--------------------------------------------------------------------------------
Condition
Some customers may comment on an engine oil leak.

Cause
Upon initial diagnosis, it may be determined that the leak is coming from the rear cover gasket. This condition may be caused by engine block porosity on the sealing surface. This issue pertains to aluminum block applications only.

Correction
Follow the steps for Oil Leak Diagnosis in SI to determine the source of the leak. If the leak has been diagnosed as coming from the engine rear cover assembly, refer to Engine Rear Cover Replacement in SI and remove the engine rear cover assembly. Inspect the engine block and engine rear cover for porosity on the mating surfaces.

• If porosity is found on the engine rear cover (see illustration below), replace the engine rear cover assembly, GM P/N 12633579.

• If porosity is found on the engine block, use the following procedure to apply RTV to repair the engine block porosity.

The porosity issue is in the gasket sealing surface at the top of the cover, near the high pressure oil crossover port. Refer to the picture below. The oil leaks by the gasket and runs down the side of the cover, and may appear to be a leak at the t-joint area of the cover. The fix is to replace the cover with GM P/N 12633579. Also, if porosity is found anywhere on the sealing surface of the engine block, use the following procedure to apply RTV to repair the engine block porosity. Refer to the illustration below.








Important: Clean any residual oil from the block and cover before applying the sealant in the next step.

•Wipe a small amount of RTV, P/N 12378521 (in Canada, use P/N 88901148), onto the surface using a plastic scraper to fill the porosity.
•Remove any excess RTV material, especially from inside the high pressure oil passage. Refer to #1 in the above illustration.
•The joint may be closed immediately after applying the RTV. Total joint time after the RTV has been applied must be under 20 minutes.
Important: Refer to Engine Rear Cover Replacement in SI and follow the tightening specifications and sequence.

•Reinstall the engine rear cover using a new gasket and a new crankshaft rear main seal. Refer to Engine Rear Cover Replacement in SI.
Parts Information
Important: For Saab (U.S.) only, use P/N 88861206 - Engine Oil Dye (U.S.) or equivalent.

Part Number
Description
Qty

12574293
Gasket - Crankshaft Rear Oil Seal Housing
1

89060436
Seal, Crankshaft Rear Main
1

12378521

(in Canada, use 88901148)
Sealant
1

88861206

(in Canada, use 88861259)
Dye, Engine Oil
1

12633579
Housing Asm-Rear Cover
1

Petraszewsky

iTrader: (28)

^^My 05 LS2 out of a GTO had teflon paste on the rear gasket...Maybe that's what it was for?? When I rebuilt it I put teflon paste on my new seal just like th eold one had it on there although the book mentioned nothing of it...interesting

blueflamespl

iTrader: (13)

When I put my 402 in (with a LS2 block) I had a simular leak, I found that there was no sealant on a oil galley plug above the filter, I removed the plug, put sealant on it and re-installed the plug solving the problem. Just another thing to check. Good luck.

Kurt

racecar

1Quick, Thanks for the info on block porosity. Oh that's nasty to have to pull the trans and do that operation. I hope that I never have that.

Here is my update: PROBLEM SOLVED: You won't believe this.
I took the headers off to get a good look above the starter because that is where I see most of the oil on the right side of the engine. It's always dripping from the starter. No leakage from the crank sensor, none from dipstick, none from main cap bolts, but the starter bolts were dripping with oil. I cleaned the bolt holes and siliconed the inside starter bolt that goes into a blind hole. Could not find anything else leaking. Drove the car 30 minutes yesterday, 40 minutes today, there is not a drop of oil on the garage floor. Incredible, it took me all friggin day to silicone one damm starter bolt, but it was worth it.

I also took out the right side bellhousing bolt that is closest to the head bolt, and put silicone on that because it intersects that head bolt hole, but that is the bolt that is on the bottom row outside of the valve cover, I cannot believe that did anything.
I can't believe that the starter bolt was the problem. I'm happy now.. Thanks to all for your ideas.

sschoeffler

iTrader: (24)

I've got a leak on mine also, but my block isnt aluminum, its an iron block LQ4. I am always noticing a little oil drop on the starter bolt. The motor has only 800 miles on it and when I built the engine, I built it from the ground up, everything line honed, balanced, blueprinted, best internals, GM gaskets, etc etc so there should be no reason for a leak. I've ruled out oil pressure sensor, rear main seal, rear seal, crank seal, oil filter seal, intake, oil level sender, so I was baffled at where the oil could be leaking from. Now I will pull a starter bolt throw some silicone on it and see if that cures the problem. Its never been a problem its just annoying as **** when I get under the car and see an oil drop on something that has less than 1000 miles.

racecar

I hope that works for you Sschoeffler on a steel block. My starter bolts always had oil dripping off.

I can't explain what that hole taps into, but it worked for me. It's nice to see the garage floor stay clean.

cam

iTrader: (9)

Hmmm interesting. Im going to take a look at mine before I stab it back in the car. 1quickirocz Do you have any pics of the affected area? Or a link to some pics I couldnt find anything with a few searches. Thanks

racecar

UPDATE 5/17 I have driven over 100 miles since I put silicone on the starter bolt with only a few small spots of oil on the garage floor. I thought all was good until my buddy was following me over the mountain, and I hit 6000 a couple of times, and a big cloud of smoke blew out from under the car. It's back, damm it. At street rpm it's fine, or up to 4000, or 5000, but at 6000 it cuts loose. I went back out on Sunday and ran the crap out of it until it was smoking like a house on fire. Now I have plenty of oil in the bellhousing, and on the starter. I have no choice but to replace the rear main seal and rear cover gasket. I used my LS6 cover on this new block, the part numbers have changed, so I ordered a new cover and gasket and seal. Anybody have tips for pulling a C5 trans with the car on jack stands???

cutlass_455

iTrader: (2)

Are you sure its being ventilated properly?? Make sure your PCV system is functioning correctly.

racecar

That's an interesting point. I wish I would have tried some experiemnts before I started taking things apart.
I have a hose from the valley cover that runs to the firewall, then loops back into the vac port on the intake behind the throttle body. I put a T in that line and ran a vac gauge, It has 25 inches of vac at idle and low rpm, and dropped to 1 inch vac at 6500, so there is always vac in there. I don't know how that oil is getting out. Of course my gauge with the T is an average between the vac, and the crankcase pressure. There has to be some pressure in the crankcase, but I don't think it's high. Do you agree with that?

Petraszewsky

iTrader: (28)

Now that I just got my engine started...It's pouring oil from the starter bolt closest to the block!!! I can't see any oil in the bellhousing through the inspection hole...You think som RTV or Silicone on the starter bolts would fix this?!?!?1 and which would be better RTV or Silicone?? I really don't wanna pull the engine again!!haha