I have a 2000 Yukon XL with a small oil leak on my driveway every day.I have been told it is a main seal between engine and transmission quoted $895 to repair and a second opion that it is a oil pan gasket Quoted $285 to repair.Is there any way to tell whether it is the oil pan or the main seal.Thanks

not told what leaks and to where.
we can no see leaks blind in text box.
axles?
autotrans
manual trans.

cause are only 3.
bad gaskets and seals
overfilled. (never do that)
or on ENGINE ( )PCV valve clogged and engine pushes oil out
rear main seal and to the TC and bottom bell housing leaks oil
and is not the transmission, leaking. fooling owners.
oddly
other causes, 4wd axle vents clogged with mud or bug nests>

no engine told
no transmission told at all(options day1 new car)
RWD
Front; with Mitsubishi R4A51 Transmission
or Front; with Mitsubishi V4A51 Transmission

you newed to pull the rear u bolts and take th drive shaft off then you can replace the seal its realy not hard

If you smell burning oil, you may have a leak in the engine compartment reaching the exhaust manifold and burning on contact. The most common cause for that is leaking valve cover gaskets. If you are losing oil with NO signs of external leaks, the engine may be burning it internally. Valve stem oil seals, worn piston rings, blown/leaking head gasket are a few causes of that.

There can be alot of causes, such as valve covers leaking, oil pan gasket leaking, oil filter leaking, rear main seal leaking, front timing chain cover seal or gasket leaking even bad rings. Does it smoke out of the back? Your valve seals could be leaking. Best way to find out if you have a leak is to inspect the valve covers manually, or take newspapers and lay them under the entire engine on the ground, and it will leave the tell tale stain of a leak. Hope this helps.

What size engine ? 4.3 L vortex P0300 random misfire code is usually associated with vacuum leaks , but could also be low fuel pressure , plugged fuel filter , fuel pump problem , clogged injectors etc... doing fuel pressure an flow testing would confirm or eliminate that as a problem . Fuel injector balance testing would confirm or eliminate clogged injectors .

absorb the frluid into a white paper towell ... if it is red in color then its transmission fluid .... if its clear or brown then its likely engine oil ... if the transmission is leaking a little then there are additives that can be put in the transmission to soften the seals .. that will often fix small seal leaks ...if the leak is slight and not damaging driveways then its not likely to cause major trouble as long as you keep your eye on the transmission fluid level .. ... if its engine oil then you could have a leaking valve cover gasket, oil pressure sending unit (sensor) ... or it could be jjust from spills as oil is changed or added .

It's not usually called this, perhaps it was a "main seal leak"? Suffice it to say that it is not possible to replace this seal without removing the engine or the transmission as it resides behind the flywheel. Or perhaps they said "master cylinder leak", in which case it is a matter of replacing the brake master cylinder with a rebuilt unit or at the very least, the seals on top of the master cylinder that mate with the brake reservoir.

Hi,

If somebody told you that you have a main seal leak what they meant was the round seal that is around the circumference of the output shaft of the crank. This same output shaft is basically hooked up to the transmission, or through to the transimission through a clutch. Well after some time, the round seal, it looks something like a flat donut, leaks. Imagine stretching a small spring around a shaft of steel and wrapping the spring in rubber. It will stop the oil from leaking along the shaft and out of the engine. After wear and tear, it needs to be replaced.

If this is the case, well, given that you have not said what type of vehicle you have, you would need to either pull the engine out or drop or pull out the transmission to get at the shaft and replace the $10 seal part. A lot of work for a small item but it will continue to leak until of course you run out of oil and ruin the motor.

I hope this helps somewhat.

First, do you see oil leaking on your driveway? Have you looked under the car and checked to see if any oil is dripping?A rear main seal will drip down the front cover plate of the transmission sometimes from the inside, appearing like a front seal leak on your transmission but the oil will not be red fluid you would expect if that were the case. I would not worry about rear main unless you see a leak there. Look your entire engine over and check for leaks everywhere. Several small leaks can add up to an overall large oil loss. Correct the larger ones first.
Generally all seals will last far longer if you change your oil frequently using a good quality lubricant. If you are loosing some oil, use one of the oils made for high mile engines. I suggest you use a mild additive like marvel oil 1pint with every oil change...it removes sludge, carbon and varnish buildup without the drawback of knocking it loose all at once, where it could plug up your oil pump screen. (it also smells good) Change oil every 3000 miles for the first three or four intervals, then consider using a good synthetic oil. Synthetics far outperform any other lubricant in every area! Avoid overheating your engine...overheating does more damage to seals than any single other item...When seals get very hot they harden up, crack and fail.
Good luck with your car!!!

neither...rear main seal is broken do to the camshaft rubbing against it. Even fixing it with a new seal it will just leak again..best to just watch the oil lvl and add accordingly.