rear main seal leaking

[rparlaman]

Need help with possible rear main seal leaking. When running at idol, i can see oil leaking but not runing it does not leak, rear main seal. ! Has anyone change one? How hard is it, i might just get the transmission rebuilt at the same time.





Thanks Ron

















1992 CTD 170,000miles,01 HO Banks Power pack,jacobs E brake,50 gal trans flow,30 ft forest river 5th

 

[1stgen4evr]

leaking seal

Ron, nothing is hard if you have the tools and knowhow. With 170k you may want to do some service to the transmission. Is it automatic? Mine was getting a little weaker at that mileage. A better torque converter would be a good investment also. My transmission with 260k is still working but the converter is very weak. You probably aren't going to do the rebuild yourself. Any shop that can do the rebuild will have skills to do the seal.



Also, some of the earlier trucks had a problem with the oil pressure relief valve. You might want to put a direct reading guage and see if you have too much oil pressure. The rear seal is usually good for more miles than you have. The over pressure can be intermittent. Do you ever notice any oil leak at the filter seal as well? The two together indicate too much pressure. Also at 170k you could expect that everything has worn in so as to not be a problem but it is still a consideration.



If the pressure relief is indicated, that is another propersition. That will be a good deal of work changing the pump. Not hard just long.



1stgen4evr

James

 

[Grey Wolf]

Ron,



The rear main isn't hard to do, most of the time is spent removing the transmission, etc. just to get to the seal !

 

[rdodd]

I recently had my rear main seal changed because of a leak and when they pulled out the seal they found it fit tight around the crank but had tore out of the seal cage allowing it to turn with the crank. I installed the new teflon seal from cummins, and no more leaks.

 

[DKasper]

I had one done last year on my D350 -- a local shop charged me $190, including the part from Cummins. For that price, I thought it was money well spent instead of me wrestling with the transmission!

No more leaks -- the old seal was in 4 different pieces.

 

[boatpuller]

I would have gladly paid $190, It's not real hard, there is just a lot of stuff that has to be moved to get to it, also if it's an automatic I would replace the flexplate while it's apart, I did on mine, it's a whole lot easier while you're in there.

When I did mine I just slid the transmission and transfercase back about 5" didn't take it completely out, just slid it back on the crossmember.



Hope this helps,

Caleb

 

[CumminsPower98]

I did a rear seal in a '93 and it had also spun in the housing. I had never seen this before. The new National seal is a much better seal with a rubber outer rather then steel like the old one.