Topic: rear main seal

[zebo87]

hi guys,
          my rear main seal is leaking and i want to change it. i just dont know how involved it is. i know i have to disconnect the transmission. i did have a question though. it seems like my transmission isnt acting right. when i take off it seems like it doesnt want to catch right away. almost like its going to die. it doesnt but it has bever done that. there definetely is a problem because the torque isnt all there. would this have something to do with the rear main seal. any help would be greatly appreciated. thanks again.

[Soaring]

Yes, you have to take the transmission out of the engine in order to replace the rear seal of the engine.  It would be easier to take the entire engine out of the engine bay if you don't have a lift.   As far as the transmission not shifting properly, first check the fluid level, and if that is OK, you need to adjust the bands.  Go to the Classic section and the FAQ section of that forum to read about how to do that. 

[zebo87]

no i dont have a lift i know i had to remove the engine from the transmission. al i have is 2 floor jacks and 4 jack stands. i also only have a few weeks before i go back to work. so i have to get it done soon. about how long does that job take.

[Soaring]

Are you planning on doing the job yourself with only two floor jacks and 4 jack stands? 

[jethat]

My experiance has been when that seal fails it is because the bearing are worn and most likely the engine is in need of an overhaul. Replaceing the seal is a major job and with the work you have to put into it just to stop it from leaking then to run the risk of the leak returning shortly is not worth it. Now would be a good time to consider freshing up the engine. Might not be as expensive as you might think..

[zebo87]

the engine is fairly new. its a crate engine with approx 35-40k on it. it cant need overhauled already can it. i dont beat on the car. so its not driven hard.

[jethat]

If thats the case then go ahead an drop the tranny and replace the seal. Harbor freight sells a cheap tranny jack adaptor i've used to do things like this. Make it allot easier. Get some tall Jackstands and use that tranny jack to lower it. You could also rent it but its almost the same to buy the floor jack adaptor from harbor freight.

[Soaring]

Yeah, it's not time to overhaul yet.  Do some research on how to replace the seal.  Best I remember, you have to undo all the rods and slide the crank foreward then replace the seal and slide the crank back into place.  It has been about 40 years since I have done this, so can't remember all the details.  There may be some new tools invented to do this since I did it.  There are special oil additives on the market that are designed to swell the rubber of the rear seal and cause it to expand, thus sealing off the leak. You can also try using thicker weight engine oil, like 50 weight. The thicker oil can fill in the gap between the seal and the crankshaft, and could slow the leak down. Unfortunately, the only real cure is to replace the seal itself.  If you have a mechanic do it, it will cost you twice what you may think it should.  If you do it yourself, and don't know what you are doing, it will cost you 3 times as much as what you though.   

[jethat]

If its an 82 engine it has the one peice seal on the back of the tranny. Cant remember the year they changed from the old 2 peice rope seal but i know it was sometime in the mid 70's. If a 2 peice you have to drop the oil pan and remove the rear main bearing cap then you have to push the seal out. Those are worse then the 1 peice seal where you have to drop the tranny. Once the trannys out it take 10 minutes to replace the seal. I've done both. My Mach I has the 2 peice seal I replaced it and ended up pulling the engine to overhaul it the next year. An extreme drag that was. Had to jack up the engine as far as it would go and all to get the pan off. Pan BARELY came off with the engine in the car. Bottom line is I think the OP has the 1 peice seal but he better find out for sure. be a drag to drop the tranny only to find out the pan has to come off.

[zebo87]

well time, money and experience are three things i dont have. im thinking of going with the stop leak stuff with a heavier weight for now. im probably going to get a newer one soon anyway.

[Soaring]

That's probably a wise move. 

[zebo87]

thanks for the help. i knew the job was a big job but not that extensive. thanks again.

[petty]

hi guys,
          my rear main seal is leaking and i want to change it. i just dont know how involved it is. i know i have to disconnect the transmission. i did have a question though. it seems like my transmission isnt acting right. when i take off it seems like it doesnt want to catch right away. almost like its going to die. it doesnt but it has bever done that. there definetely is a problem because the torque isnt all there. would this have something to do with the rear main seal. any help would be greatly appreciated. thanks again.

Rear seals are not easy to fix. To stop the leak, you need to pull out the tranny and replace the seal. Check this out for directions, how to replace a rear main seal.

[zebo87]

that job is done now.

[Soaring]

What did you wind up doing to replace it?

[zebo87]

well i had to change my bellhousing and block plate so naturally with the trans out the way it was easy.