I am trying to identify where a leak is coming from looks like bolt on tranny, but it is my engine oil. not rear seal. 2000 chevy suburban 2wd lt

front seal, leaking oil means there is less oil in engine. continue and you will a new engine, have it repaired quickly.

Dear Sir,
Here is the oil leaking Problem Identifying Technique

Engine oil leaks from the valve cover gasket are common.

The intake manifold plenum gasket may leak and cause increased oil consumption/burning and a spark knock during acceleration; the gasket should be replaced.

External oil leaks from valve cover gaskets, intake gaskets (front or rear), and the rear crankshaft (rear main) seal area are common. The rear main seal is an unlikely source. Normally, the bearing cap mating surfaces (as well as the sealing surface between the oil pan and bearing cap) are the source for the leaks.

Engine oil leaks at the distributor can be misdiagnosed as leaks from theintake manifold seal, oil pan gasket, or rear crankshaft (rear main) seal. A revised distributor is available if oil is found inside the distributor.

If the oil filter casing shows signs of distortion from excessive oil pressure, theoil pump should be replaced.

Often misdiagnosed as a leaking oil filter gasket, the oil filter adapter can seep from between the adapter and engine block.

Carbon buildup on the top of the piston is common. As the buildup increases with mileage and over time, symptoms may vary from light ticking, to ticking/hammering, to hammering/knocking noises. Fuel injector cleaner often solves the problem.

I think it helps to analyse u r Problem

I'm fairly certain that your engine does not have a full circle external main seal (if when you remove the trans and flywheel you find the rear crank flange is bolted to the crank and not part of the crank, then I'm wrong) If it's not an external seal, it is two piece, located in the rear of the main bearing cap. That makes it necessary to remove the engine oil pan and the rear bearing. Before contemplating doing anything with that, make very sure that the leak is not from the intake or valve covers first. Otherwise you'd be doing ton of work for no reason. Wipe everything down and look carefully. If it's leaking fast it shouldn't be difficult to see.

double check for leak at rear of engine where engine block mates the transmission .the housing for the rear seal is bad about leaking on these engines at 100,000 miles

If it in fact it is the main seal you should see tranny fluid leak at the point where the engine bolts to the transmission. With car in park and brake on, start engine and carefully look under to see where the fluid is coming from. If you see no fluid leakage, place the front end (this assumes front wheel drive only) on jacks stands and block the back wheels. Have a friend start the car and with their foot on the brake place the car in drive and SLOWLY remove their foot from the brake and allow the front tires to spin (DO NOT REV ENGINE) watch for leakage as wheels turn. If you see leakage at the engine/tranny mating surfaces then yes I expect it would be your main seal. I'd take avery good look at tranny cooling lines to and from the radiator, if these leak it is very heavy.

I hope this may have assited you,
Tom

Where is the leak? Toward the middle or at the right or left sides near the rear wheels?

Sounds like the rear engine/crank seal is leaking. Transmission must be removed in order to replace this seal.

I would have a mechanic look at it for you. Sounds like it could be an oil seal or it could have a crack in the case or it could be a rear engine seal is shot ?

you have several points to check!
the dip stick tube has a "O" ring seal at the bottom where it fits to tranny.
a reverse switch on tranny & the shifters selector shaft has a seal that may be leaking !
there are the cooler pipes from cooler to tranny [in & out] plus pump seal to the torque converter [leaks out between engine & tranny bellhousing] & then there are the drive shaft or shafts seals
so wipe it all clean & park it in a diffrent clean spot!
some will only leak when its runnung due to tranny,s internal pressure!

http://www.kick-fix.com/engine/engine-rear1.jpg

i bet a photo speaks 1M works.

next question will be how do i get there.
nut shell
oil of of tranny, oil of of xfr case.
all prop shafts off.
cross members off tranny.
tranny lift in place.
shifters all removed.(center console off)
unbolt bell housing from motor.
bingo, tranny is out.

or , put jack under tranny
pull motor.