Oil leaks on Chevy LS engines

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Dec 31, 2017
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Location
SE British Columbia, Canada
Chevy LS engines are generally great for not having oil leaks. Mine is a 6.0 in a GMT 900 Burb. It has 260,000 miles. After about 200,000 miles it has a bit of oil leakage.The first photo shoes some oil accumulating at the bottom of the pan in the area between the fill plug and the oil filter. There are no leaks at the oil filter itself. This’s a straight up view underneath the oil pan.



4299BCFD-1F0A-47E7-BA95-5186F0867801.jpeg
 
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If you remove that inspection cover on the trans. bell housing, is there oil in there? Could be rear main, or the rear cover leaking.

Is the area where your oil cooler lines or blockoff plate mount to the side of the pan dry? If no, could need a new oil cooler gasket.
 
Clean it all off first. Have you ever replaced the drain plug? It has a built in seal, maybe it's worn enough to leak? Rear main? Oil pan rails?
Good first steps, clean it off and check the drain plug seal.

Yes, oil can seep out of that hole.
 
If you remove that inspection cover on the trans. bell housing, is there oil in there? Could be rear main, or the rear cover leaking.

Is the area where your oil cooler lines or blockoff plate mount to the side of the pan dry? If no, could need a new oil cooler gasket.
I’ll look for the plate.Thanks.
 
I haven't seen a truly high number of vehicles meeting this criteria so it's more of a casual observation, but the rear main seal seems to have a much higher rate of starting to leak above 250K.
 
Clean it all off first. Have you ever replaced the drain plug? It has a built in seal, maybe it's worn enough to leak? Rear main? Oil pan rails?
I don't get a drip at the plug, but I’ll watch. Notice it is in the side and not the bottom, so a drip should form I would think, but I’ll clean it and check. I am planning on dropping the pan in May to replace the Oil pump O ring so maybe I’ll learn something.
 
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Oil pressure sensor leak? It's directly above the bell housing
Good point. I watched a You Tube video of two mechanics preparing to drop the transmission to replace a main seal. It was a 4 wheel drive and they had to drop the transfer case first. When they dropped the transmission, the look on their faces was priceless. The leak was from the pressure sensor. I will check.
 
Good point. I watched a You Tube video of two mechanics preparing to drop the transmission to replace a main seal. It was a 4 wheel drive and they had to drop the transfer case first. When they dropped the transmission, the look on their faces was priceless. The leak was from the pressure sensor. I will check.
Link?
 


Looks like I imagined the look on their faces, but you can imagine what expression they might have had. They found the leak at 17:14. There may have been a rear seal leak as well but I'll bet a lot of the oil dripping on the ground was from the pressure sensor and possibly the cam sensor. They changed the rear seal anyway after installing new sensors.
 
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