'99 5.7 liter rear main seal leaking

[COBALT]

The '99 tahoe I'm constantly whining about appears to have a rear main seal leak. It has the usual automatic 3spd with overdrive transmission, and I'm noticing some blowback all over the transmission case whenever I do an oil change. It hasn't gotten bad enough to cover the entire case, nor is it burning up on the exhaust yet, but it looks like it is coming from the rear main seal.

Do these 5.7l engines have a two-part seal that can be replaced externally while the engine is still in the rig (by moving the transmission out of the way), or do I have to get nasty with it by replacing it out of the truck with the bottom end of the engine exposed?

[bwood]

The 5.7L has a one piece rear main seal since 1987 in the trucks. You can do it by removing the tranny instead of the engine. If it is a RMS leaking the oil should look like it is coming out of the transmission bell housing. You can remove the inspection cover (you may also have to remove the starter) and see if there is oil all over the place inside.

[clinebarger]

Originally Posted by COBALT

The '99 tahoe I'm constantly whining about appears to have a rear main seal leak. It has the usual automatic 3spd with overdrive transmission, and I'm noticing some blowback all over the transmission case whenever I do an oil change. It hasn't gotten bad enough to cover the entire case, nor is it burning up on the exhaust yet, but it looks like it is coming from the rear main seal.

Do these 5.7l engines have a two-part seal that can be replaced externally while the engine is still in the rig (by moving the transmission out of the way), or do I have to get nasty with it by replacing it out of the truck with the bottom end of the engine exposed?

Make sure its not coming from the oil cooler adapter thats between the oil filter & block (if your truck is equipped with a oil cooler?)

[COBALT]

Originally Posted by clinebarger

Make sure its not coming from the oil cooler adapter thats between the oil filter & block (if your truck is equipped with a oil cooler?)

Nope. Pretty standard setup. Just for the record there's never any oil on the filter, and it doesn't seem to be coming from the front, sides of the oil pan or from the plug. I checked up top to see if the valve covers are leaking and they don't seem to be. The rear main crank-to-flex plate flange looks pretty wet, but I can't get my hand in there to check.

I'll see if I can pull the inspection cover and take a look. If I can replace the rear main seal by pulling the transmission at least that's something. The bell housing looks more "complete" than the older transmissions, so the inspection cover doesn't look like it bolts up from below to cover the torque converter and flex plate, so the inspection cover looks flat and most likely bolted to the bell housing from the front instead from underneath. I replaced the starter a couple of months ago, and I think you're right - I'll have to remove it to get to one of the inspection cover bolts. We'll see.