How do you replace the rear engine main seal in a 1999 Chevy Tracker 4 wheel drive?
Pull the engine.
How long can you drive 1998 Chevy Tahoe after service engine light comes on for catalytic converetr?
It is a one piece seal so either the engine or the transmission must come out to replace the rear main seal. If it is a rear wheel drive vehicle it would be best to remove the transmission but a 4 wheel drive vehicle may be easier to remove the engine. It would depend on what equipment and tools you have available.
On Chevy Suburban 1999 starter is turning but the engine doesn't catch When started though the engine runs smooth and nice Can it be timing or what else?
It depends on how many miles you drive, and how long you want your car to last. In General you should replace the engine oil and filter, the transmission oil and transmission filter and drain and replace the radiator coolant. You should also replace your air filter,and if your car has an external fuel filter, replace it. If you drive a lot of miles, your engine oil may need to be change sooner.