Has anyone had to change a rear main seal? There was some oil spots on the driveway today, and it turns out it was our '94 Chevy truck, my Monte Carlo has a very light leak from the rear oil seal... just barelly a little oil in the oil pan, and a little bit on the bolts for the inspection plate..... maybe a few ounces. Not a big deal I know... but what am I up against if I have to change it a couple of years from now? And how common is it? I know it's common on a lot of engines, but how hard common is it here?

 

to do a rear main seal on a engine you will have to drop the trans or take both out as a unit with a engine jack then seperate the two for the front wheel drive vehicle. for the truck you can drop the trans and take off the fly wheel to get to the rear main seal. my question is what type of engine is in your truck? the reason why is there are some rear main seals on gm engins where you have to have it sit on a engine stand to do it same way with some ford engins. where you have to take off the oil pan and losen a little of the crank to replace the seal but majority of both engins it is pretty much straight forward. as in disconect the trans in the car take out the engine while on the hoist pull out the old seal with a tool designed for it and tap in a new one with a socet the same size as the seal. but if you have the type that you have to drop the pan and do the extra work keep in mind it will be worth the extra work do to being able to get upgraded better seals and be able to replace any thing that you want to upgrade internally. but becarefull and check what type they are and look up how the seals go in. its not that hard but not knowing what engins are it will be hard to tell you. i have a ls1 in my silverado and i had to drop the pan and take off the rear bearing of the bottom end to replace the rear main seal. my advice if you are doing the rear main seal i would do the front mail seal do to you are already there and you probably have to replace it shortly after replacing the back one. i did that and had to do it

 

sorry about the long post i didnt want to say its easy or hard. with the front main seal the reason why i did mention it i made the mistake in not doing it when i pulled the engine to do the back seal and when a week went by the front seal started to leak like a open wound that hit a artery the front was easy to do then the back all you have to do is to take off the bottom pully and pull it out and tap it in. less work but a little agravating if you have it in the vehicle.

 

The '94 Chevy has a 5.7 in it. I think it might actually be the valve covers because there is oil all over the side of the block on that one though. I put a bottle of that treatmetn stuff you buy at the part store in the crankcase, we'll see how that does for now. It's really not leaking enough for me to worry about pulling the engine yet.

 

I hope it's easier than in our '73 Mercedes 220. It required pulling the engine to swap it out. $20 part; $1500 labor. Ouch... I couldn't do that job myself.

 

Shoot... if I'm going to have to pull the engine I might as well just buy a gasket and seal kit and change the heads, intake, oil pan, exhaust, and whatever!

 

the older sbc was a 2 piece rear main seal and could be done with motor and trans in the car. the newer sbc is one piece and your going to have to pull the trans to do it. idk if 85 is the first year for the one piece or not. i would be sure to do a check and make sure your not leaking from intake, valve covers, distributor before jumping the gun and taking this on before its absolutely necessary.

 

I can tell you from my teenage lube shop days (and I've calculated that I have changed oil on an estimated 50,000 cars - no exageration) that 85% of car have a leaking rear main to some extent. Even the BudChev has a little leak, but it does not lose oil. It is the most common leak and the most treatable leak with an oil stop leak additive. I have seen the Wynn's stuff seal severe rear main leaks. A small block Chev rear main leak couldn't be a more textbook case

 

As long as it has been a problem on nearly all cars, it seems like an engineer somewhere would have figured it out. I put a bottle of No-Leak in it and we'll see how that does. Thanks a lot, guys.

 

So I have the two piece small block chevy rear main seal, that I am trying to change while it is in the vehicle; I have the pan off, oil pump off, rear main bearing cap off, and for the life of me I cannot get the upper half of the rear main seal out... (engine block side).

I have tried a punch/screwdriver and no luck it will not budge, all that appears to be happening is the side I am hitting on is crumbling...

suggestions?

thanks in advance.