Pinpointing oil leak

[SDHNTR]

Ok so I have an oil leak that I think is the rear main seal, but not totally sure. The leak appears to be coming from between the black metal plate behind the oil pan and the front surface (bell housing) of the tranny case. It does not smell like gear oil, but I don't know if I'd be able to smell a difference from just a little drop. Then it drips down onto the universal joint of the front driveshaft.

So my question is... Is it rear main seal leaking motor oil, is it the tranny leaking gear oil, or is it the pinon seal on the front axle leaking and then splattering the leaking oil as it spins around while driving? (But would it spin at all when not in 4x4?)

It does not seem to leak much when the truck has just been sitting. As in wipe off, let sit overnight and check again -- not much. But if I wipe off then drive all day, then let sit, the drips are quite obvious.

Any idea how I can nail down the source of the leak?

 

[jshryder]

when you turn the motor off does it smoke sometimes? if so it might be in the rear of the head gasket thats leakin alittle oil, if not then you might want to check the tranny, if not in 4 wheel the front drive shaft shouldn't be spinning I would think

 

[bigbsvo]

Just guessing here that it's a V6?

 

[fourwd1]

... So my question is... Is it rear main seal leaking motor oil, is it the tranny leaking gear oil, or is it the pinon seal on the front axle leaking and then splattering the leaking oil as it spins around while driving? (But would it spin at all when not in 4x4?)

To begin with, it helps to know what engine and transmission you have.

It could be the motor or trans, it's unlikely it's the front pinion seal, their would be splatter up front, not near the back of the motor.

Any idea how I can nail down the source of the leak?

If the leak is bad enough, it should show up if you check the levels frequently enough. You should also be able to tell from the viscosity, gear oil is thicker than engine oil, and engine oil is thicker than ATF. Also, each has a characteristic smell.

 

[SDHNTR]

Motor is 22 RE, 5 spd manual. No smoke at all. Eveything runs perfect.

I have not noticed the leak in fluid levels at all. It's not bad, yet. I have all but ruled out the front axle leaking. My best guess is that it is coming from between the black metal plate behind the oil pan, where it bolts up to the transmission, and the tranny housing itself. It's not the oil pan gasket as it is clean. Does not smell like gear oil, but again, I'm not 100% sure as I don't know if a drop on my finger would be enough to smell.

Dare I try a little Lucas Oil Stop Leak?

 

[turboSR5]

Sounds like a rear main seal. I think I already went over what I thought about "Mechanic in a can" in another of your posts so I will refrain, lol.

 

[SDHNTR]

Yeah, I know. I plan on rebuilding this motor in the next year or so anyway, so paying for an expensive rear main seal job doesn't make a whole lot of sense. Was optimisticly looking for a quick and easy fix.

 

[fishrod]

Hijack

Can I hijack this thread and say that I am having trouble pinpointing an oil leak also. 3vze 5sp manual. Leaks are quite obvious, the whole underside of the engine is covered. Was once told it was a rear main seal, but im not so sure. It burns oil (smell it quite easily when stopping at lights or at the end of a trip) especially in summer on hot days you could visibally see the smoke coming out the engine bay from the oil burning off the hot engine block. Also drips a few drips everyplace I park it.

However I rarely need to top it up between oil changes (if at all). Im pretty sure its oil, smells like oil, I know the off smell of tranny/gear fluid.

Could it be valve cover gaskets? Ive heard that going around alot. HG was replaced <12 months ago, should/could the valve gaskets been done at the same time? How long does the FSM say valve gaskets take to replace?