hohieu Posted October 12, 2011 Share Posted October 12, 2011 I'll be replacing the clutch on my '99 Forester with 170K on the odometer this week. I have an aluminum separator cover on hand in case the original is plastic. In any event, I plan on resealing it and doing some other odds and ends while I have the tranny out. I know there's some debate about whether to replace the rear main seal so I'd like to hear your thoughts. I already have an OEM viton seal but am wondering whether I should leave the old one in there if it's not leaking. Thanks for you thoughts. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted October 12, 2011 Share Posted October 12, 2011 I should leave the old one in there if it's not leaking. Thanks for you thoughts. YES, YES, YES, leave the old one unless it is LEAKING big. this is the one seal that can last the life of the car. but i would check it rather than just ignoring it. you might consider pulling the engine instead of the trans, depending on your shop set up. less time on your back under the car. Quote Link to comment Share on other sites More sharing options...
davebugs Posted October 12, 2011 Share Posted October 12, 2011 My opinions. Pull engine. Dont replace rear main unless doing more than weeping. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 12, 2011 Share Posted October 12, 2011 what they said. plan to replace it (have the part on hand and visually check it) - but if it's bone dry and the engine isn't questionable or sat for years.....i would feel content not replacing it. couple days ago i installed a transmission in my 03 H6 OB Sedan and i can't recall what i was thinking that night but i didn't bother to pull the flexplate off to inspect that seal, which is something I would never skip normally? and i even had purchased the seal, that's just silly....hopefully it's as dry as just about every other rear main i've ever seen. Quote Link to comment Share on other sites More sharing options...
hohieu Posted October 12, 2011 Author Share Posted October 12, 2011 Thanks for the emphatic responses, in bold red letters no less. I'll check the seal and will leave it alone if it's dry. I'm pulling the tranny because I'll be doing this in a friend's driveway and don't have access to an engine hoist, only a tranny jack. Now if my headgaskets were leaking, the decision would be a no brainer. Quote Link to comment Share on other sites More sharing options...
davebugs Posted October 13, 2011 Share Posted October 13, 2011 If you were on this end of the state I could hook you up with a place and the necessary tools. DON'T forget the OEM TO bearing clips! Quote Link to comment Share on other sites More sharing options...
hohieu Posted October 13, 2011 Author Share Posted October 13, 2011 Thank you Davebugs, that would be incredible. But at least having a driveway in the burbs means I don't have to keep an eye out for buses and delivery trucks as I usually do most of my work on the street in front of my house. I have the NTN T-O bearing and clips (and a new pilot bearing, too). I'll be using Honda Pro-Moly 60 on the tranny input splines -- very popular among motorcyclists for lubing shaft drive splines. Quote Link to comment Share on other sites More sharing options...
davebugs Posted October 14, 2011 Share Posted October 14, 2011 Good luck. Glad you got the clips. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted October 14, 2011 Share Posted October 14, 2011 Incidentally - the factory Subaru rear main seals are made from Viton. That is why they last so long. As stated if it's not leaking I wouldn't mess with it. But I *do* check how hard the seal rubber is getting in addition to checking for signs of leakage - sometimes you find one that's been replaced by someone that was over-zealous when they did the clutch, etc and not all of the seals that are out there are of high quality like the OEM part. If it looks like it's been changed and is getting old - I will change them. The thing is - when you change a rear main seal you had better KNOW how to install seals. One of the other reasons people are told to leave them alone is because a seal of that size is difficult to install for a beginner. The amature installation failure rate on these is high. With proper technique it's nothing to be scared of though. GD Quote Link to comment Share on other sites More sharing options...
hohieu Posted October 14, 2011 Author Share Posted October 14, 2011 A little off topic here: When I did the timing belt at around 105K, the newer OEM crank and cam seals I swapped in were also Viton. If they're not leaking at the next timing belt interval, would you leave them in there? Quote Link to comment Share on other sites More sharing options...
hohieu Posted October 19, 2011 Author Share Posted October 19, 2011 I took the flywheel and here's the deal. I have the metal oil separator cover, which I'll reaseal. But my rear main seal is seeping/weeping. I wiped some grime of the bottom of the seal to get a better look, and it doesn't seem too bad. The lip was still soft and pliant. I already have the seal so one last time here: should it stay or should it go now? Quote Link to comment Share on other sites More sharing options...
ShawnW Posted October 21, 2011 Share Posted October 21, 2011 I would replace that one. Quote Link to comment Share on other sites More sharing options...
hohieu Posted October 22, 2011 Author Share Posted October 22, 2011 (edited) Alright, I went ahead and replaced the seal while waiting for the machinist to resurface my flywheel, and I now understand why others recommend against replacing the bugger. It took me an eternity. I used a 93mm aluminum oil filter socket as my driver along with a small block of wood. I found that it was impossible to square the seal in there and that anytime it started to go in, the spring tension of the seal body would push it back out. I finally got it to go, and found it was helpful to get it 2/3 of the way into the opening by tapping around the circumference of the socket with a plastic hammer. Then tapping it flush with the block of wood, and lastly seating it properly with the socket. Almost seems having something to press the bearing into place, using the flywheel bolt holes, would make it much easier and more precise. I should have asked this beforehand but, GD, do you have any advice or tips to offer? Edited October 22, 2011 by hohieu sleep deprivation Quote Link to comment Share on other sites More sharing options...
davebugs Posted October 22, 2011 Share Posted October 22, 2011 My "high tech" rear main seal installer is a PVC coupler - just like I use for crank & cam seals with a block of wood over it to help lets say - center the blows of the hammer especially when starting the install. Quote Link to comment Share on other sites More sharing options...
hohieu Posted October 23, 2011 Author Share Posted October 23, 2011 You know, I thought I'd have to run out and pick up a larger high tech PVC coupler for the rear main seal but had the filter socket laying around. Now here's another question/thought, are failure rates of rear main seals on cars equipped with manual transmissions higher due to the heat produced by the clutch? After removal, I could see that the old seal had hardened a bit as compared to the the new one. Quote Link to comment Share on other sites More sharing options...
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