Rear main oil leak?
11-28-2017, 08:37 PM
#1
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Rear main oil leak? 
Can anyone tell me where they think this oil is coming from? Just got the oil pan gasket replaced 2 months ago and I didn't have a leak now out of no where I look under my car and there's a decent amount of oil on the ground. I think it's the rear main but I'm not understanding why there's oil on the front of the oil pan. Any info will help!
11-28-2017, 08:57 PM
#2
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If the front of the car is lower than the rear, oil can run along the pan rail from the rear to the front. Did you replace the gasket or someone else?
11-28-2017, 09:00 PM
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I didn't do it a shop did it while the car was there getting a bunch of mods installed. I don't think it's the gasket so I'm not gonna jump the conclusion and blame them because the car was fine for the past 2 months till now. The oil in the front of the pan looks like it's coming from the front of the pan and oil is getting pushed back from driving. The cars not lowered at all its stock ride height.
11-28-2017, 09:04 PM
#4
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Oh alright.. So it could easily be the front seal then. A MUCH easier fix than the rear, for sure! IF that's what it is...
11-28-2017, 09:10 PM
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I have no clue what to think. I got a cam installed so the whole front of the engine was taken off. It looks like the very front of the pan it dry it's just pretty wet under the crossmember. Then it's also coming from where the well housing meets the oil pan. There's a little hole there and it doesn't seem like oil is coming from that just the seems.
11-28-2017, 11:42 PM
#7
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Possible, but can't tell. Was there a lot of oil near there?
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11-29-2017, 12:12 AM
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Was doing research and that metal piece there is suppose to be inside the PCV valve boot. And it hasn't been in there sense I got my car back from the shop. There was oil around it and there was dried up oil all over the front of my head and along the front cover of the engine. Really hope this is where the oil is coming from but I can't see that leaking all the oil it did.
11-29-2017, 02:43 AM
#10
in the 3 engines I have tore apart.....NONE had rear main seals leaking...or rear cover gaskets......ALL had leaky front cover and OIL pan gaskets.....oil pan being the worst .....I might think its the oil pan gasket again
makes a big mess under the car !!!
makes a big mess under the car !!!
Last edited by sjsingle1; 11-29-2017 at 02:55 AM.
11-29-2017, 09:43 AM
#11
I agree with this. If you had a cam installed they likely dropped the pan a bit to get to the pickup tube bolt. I just rebuilt the engine in my Camaro, and it was leaking like crazy where the rear cover meets the pan. I forgot to put sealant on the corners of the oil pan where the sides of the cover meet the pan.
11-29-2017, 12:33 PM
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I think this is my problem. The metal piece is suppose to be inside the PCV valve boot and it hasn't been and I just noticed last night. Gonna start my car and let it run for a little to see if that's the problem
11-30-2017, 05:15 AM
#14
Go get some oil dye and pressure wash the engine really well. Put the dye in the oil and run it, preferably sitting still so there's no turbulence blowing oil around under the car. Get a black light and find out where its coming from... just look for the glowing stuff.
11-30-2017, 06:36 AM
#15
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Did the shop remove the flex plate from the crankshaft?
11-30-2017, 07:04 AM
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Yesterday I cleaned the whole engine really good then let the car sit and idle for awhile and this is what I found. I'm guessing the oil pan gasket again so I contacted the shop that did everything and they are going to be looking at it next week. Hopefully they'll replace it for free sense I already paid them to do it once and it didn't work so we'll see.
11-30-2017, 08:16 AM
#17
Couple days later I put synthetic in the engine and it started leaking from the rear. The seals on 20-year old rear cover and rear main are brittle and hard I guess from age... So I was forced to get under the car and change them. The black rubber seals broke like dry twigs in my hands.
I learned I will always change the rearmain/flexplate because its too cheap not to do before using an engine. I learned they can look "good and leak free" but can actually leak like crazy anyways.
As to the seal and shop work: Its pretty easy to screw up this process with the engine in the car, in my opinion. If you leave the oil pan on the car, In the car, then it means you would need to dry dry dry the areas around the pan gasket, and especially the corners, to get a good amount of silicone to actually seal there. For example when I plopped the rear cover back into the oil pan's "groove" it needed quite a bit of silicone on the corners to seal the areas where the pan doesn't meet or quite touch the cover. I noticed the oil would constantly flow from the sides of the pan gasket into these areas, so it took several hours of cleaning, drying, and checking, to be sure those areas remained clear of engine oil, so that the new silicone would stick.
Because you can't put silicone on a part and then slap that part up against something with oil on it. The silicone won't seal... and the result will leak...
12-03-2017, 11:25 PM
#19
I have not installed my oil pan gasket yet....but I use the high tack red spray on all these GM metal rubber gaskets now....cant hurt and less messy than other types of sealer
I am also using loctite on any gasket bolts....seems there are always a few bolts loose when I disassemble
I am also using loctite on any gasket bolts....seems there are always a few bolts loose when I disassemble
12-04-2017, 08:57 AM
#20
pretty sure fsm recommends a bit of thread locker on almost every bolt in the engine. I clearly recall it being on the head bolts, and the instructions for say, exhaust manifold bolts, also say to use it and so forth. places I normally would not (and didn't) use it. I do think there was some on the flexplate also; but I didn't use any there either. I generally avoid using it because I am going to be pulling parts off the engine in < 10,000 miles anyways. It sucks to remove...