Notorious Oil Leaks

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Had a super small valve cover leak on one of my 100's and since I've addressed it (70k miles ago or so?) nothing else. ~240,000 on both 100's currently.
 
Guys I am noticing a leak (oil?) up through service access in front skid plate. See pic below. I am thinking this is behind oil pan.
 
Pic

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mine looks the same, doesn't drip. I've done valve covers so it isn't that. It isn't coolant from rear pipes. I'm thinking rear main. Before I go there I'm going to strip the front, water pump timing belt intake etc before I determine it's the rear main.
2006 201k miles.

also could have been dipstick tube, that I fixed, which also leaks down onto or on top of engine oil pan flange.
 
jerryb said:
mine looks the same, doesn't drip. I've done valve covers so it isn't that. It isn't coolant from rear pipes. I'm thinking rear main. Before I go there I'm going to strip the front, water pump timing belt intake etc before I determine it's the rear main.
2006 201k miles.

also could have been dipstick tube, that I fixed, which also leaks down onto or on top of engine oil pan flange.
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That is rear weep hole. Where it may indicate rear main leak or transmission leak, it can be from elsewhere. Likely location is head covers (AKA valve cover).

I'd start my search by following wet (oil) up along outside of engine. Oil will travel, even up the side of engine by capillary action. But wettest will be to rear and below actual leak. Still it will all give you clues. Once you've documented all wet areas with pictures, then wash with de-greaser. Then watch close for reappearance of leak.
 
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Looks like a rear main seal leak. Degrease and verify before doing all that work.

Edit: didn’t see @2001LC prior post. Carry on....
 
I put 225000 miles on my 1999 and nary a leak anywhere.
 
I have leaks seemingly coming from everywhere. The previous owner of this vehicle was apparently a deushbag that could care less about preventative maintenance! I've replaced the valve cover gaskets, Steering rack, radiator, power-steering hoses. Now I'm there's leaks behind the timing belt and possibly the upper oil pan according to my trusted mechanic. I asked if it could be the rear main seal but he didn't thing so. He said the leak coming from behind timing belt seems to be an active one, and the oil pan seems to just be weeping.
 
ERMB said:
I have leaks seemingly coming from everywhere. The previous owner of this vehicle was apparently a deushbag that could care less about preventative maintenance! I've replaced the valve cover gaskets, Steering rack, radiator, power-steering hoses. Now I'm there's leaks behind the timing belt and possibly the upper oil pan according to my trusted mechanic. I asked if it could be the rear main seal but he didn't thing so. He said the leak coming from behind timing belt seems to be an active one, and the oil pan seems to just be weeping.
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Hey did you figure out the leak. Thanks!
 
I've got an oil leak at the front of my engine. Replaced the front main seal when I did the T-belt last December, so I don't think that's it. I THINK it's the oil pump seal, which I understand is an engine out deal. So, it's going to leak for a while, I guess.
 
100serieslover said:
I've got an oil leak at the front of my engine. Replaced the front main seal when I did the T-belt last December, so I don't think that's it. I THINK it's the oil pump seal, which I understand is an engine out deal. So, it's going to leak for a while, I guess.
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Did you put threaded locker or FIPG oil (102 or 103) on threads of T-belt tensioner and idler pulleys. The tensioner one will leak oil, if not.
 
2001LC said:
Did you put threaded locker or FIPG oil (102 or 103) on threads of T-belt tensioner and idler pulleys. The tensioner one will leak oil, if not.
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I don't recall, unfortunately. It's entirely possible that I didn't.

That being said, there was a pretty clear leak before I did the T-belt job. Sooo. . ..
 
Hey everyone, I’m working on figuring out an oil leak. After reading some comments on here I’ve decided I’ll degrease everything and see if I can find where it starts, and I’ll check the intake manifold bolts, but I think I’ve done that before.
Anyway, I have oil on the heads of these 2 bolts, and I can’t find any information explaining what this part is. Does anyone know what it is, and if there’s any reason why those bolts would be leaking oil? If that is where it’s coming from?
Thanks for any advice.
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JLink said:
Hey everyone, I’m working on figuring out an oil leak. After reading some comments on here I’ve decided I’ll degrease everything and see if I can find where it starts, and I’ll check the intake manifold bolts, but I think I’ve done that before.
Anyway, I have oil on the heads of these 2 bolts, and I can’t find any information explaining what this part is. Does anyone know what it is, and if there’s any reason why those bolts would be leaking oil? If that is where it’s coming from?
Thanks for any advice.
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the two bolts are timing belt tensioner fasteners. they are not connected to the inside of oil pump. however the tensioner wheel above it (the black) has its guide bolt (the one in gold color with hexgon Alan key) into the inside of oil pump. there is a thick washer under to prevent oil coming out. there is chance that oil can leak out from there, but usually it is due to installation error. if you just have your timing belt changed that could be the reason.

as always, for 2UZ engine, check oil check tube seal and valve cover seal first, then go to front main crank seal, two cam seals.
 
sunfic said:
the two bolts are timing belt tensioner fasteners. they are not connected to the inside of oil pump. however the tensioner wheel above it (the black) has its guide bolt (the one in gold color with hexgon Alan key) into the inside of oil pump. there is a thick washer under to prevent oil coming out. there is chance that oil can leak out from there, but usually it is due to installation error. if you just have your timing belt changed that could be the reason.

as always, for 2UZ engine, check oil check tube seal and valve cover seal first, then go to front main crank seal, two cam seals.
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Thanks for the reply. Timing belt was replaced before my ownership, approx 70k miles ago. I’m planning on doing it again in another 10-20k, so I guess if that is the leak, hopefully it can wait until then.
I will check the other things you mentioned.
 
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