Change rear main seal during clutch install?

I am planning on putting a new clutch in soon. Should I replace the rear main seal while I'm in there? If they are never an issue I'd rather not mess with it. Car has about 80,000 miles on it.

Generally not something you'd replace, unless it is leaking. There's actually 2 seals: an inner seal and an outer 'slinger'. And, if you ever replace them, I HIGHLY RECOMMEND using the proper set of special tools to do it! Very difficult without them. (I have them and rent them out.)

I have a extra rear cover if you want it. Then you can get the seal set and ready for a swap rather than messing with it on the day of your clutch work.

The special tools are very nice and make the job easy. The tools also set the main seal at the proper depth so that the slinger (second seal) can seat properly. But it can be done with regular tools. I used a press and a thick block of wood to push the main seal into the cover. Then I found that the big end of a solid piston ring compressor sleeve works perfectly to seat the slinger.

PM me if you want my extra cover and we'll figure out something for shipping.

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Suggest you inspect how close the crank hub is to the separator plate while you have the flywheel off. I had interference between the crank hub and separator plate on my 05 that drove me batty trying to isolate the problem before finding it. Thankfully the issue was covered under warranty and there was a TSB on it. If it looks remotely likely there could be interference, pull it off and open that hole up .010" - .020" all the way around. Could save you a second tear down by doing so in case it shifts during the install. Nothing worse than having to redo something twice because something was overlooked or taken for granted. Replace the slave cylinder as well. Do not reuse it. Been there, done that even though Ford told me it would be fine to do so when I asked.

As long as it's not leaking, I think I will leave it alone. Thanks for the input guys.

I forgot about the TSB on the separator plate. When it was stock I used to hear that buzzing sound when the car was cold, but now that the car is louder I don't hear it anymore. Is there a new part# for an updated plate?

Not to my knowledge. The TSB simply had the tech remove the plate and open up the hole with die grinder or similar device. Way cheaper than buying a replacement part. No more issues with mine after that was completed. Drove me nuts until I found the problem. Pulled heat shields, tightened up bolts, adjusted muffler hangers, etc. Finally figured it out. Thankfully someone on another mustang site no longer in service posted about it and actually sent me a copy of his service report with the TSB and diagnostics that I took with me. Dealer found the problem after two days and me riding with him until it finally made the noise and he then tore into it and sure enough found it and resolved the issue........just barely inside warranty.

Old theory of If it Aint Broke, Don't Fix It. However, because of the location you might want to consider it because it will leak eventually and then you are going through double labor!

06redgt said:

As long as it's not leaking, I think I will leave it alone. Thanks for the input guys.

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This.

86GT351 said:

Old theory of If it Aint Broke, Don't Fix It. However, because of the location you might want to consider it because it will leak eventually and then you are going through double labor!

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Its not difficult to replace the seal once everything is apart. Im an advocate of proactive maintenance especially when it's a labor intensive piece to get to once everything is back to together. Heres a link that shows the job
https://youtu.be/JpzefqEeVGE?t=16m8s

You are literally going to be right there at the part. I think it's silly not to go ahead and put in a new seal. Especially considering the labor to get at it later. It's like tearing down an engine to put new rings and pistons in, but leaving the old crank bearings in because "If it ain't broke don't fix it". The peace of mind alone is worth it, especially considering the cost of a new seal and the small amount of time to install it once your already in there.

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Who has had to replace their rear main seal because it was leaking? How many miles were on it? This seal seems like a good design so maybe it isn't a problem?

I have 200,000 miles on an F150 and have never changed it. But the tranny has never been out of it either. Doesn't leak a drop.

But I have only 11,000 miles on my Mustang and it's been changed twice... One time with each engine build. Because why wouldn't you if you are already there and the part is a few dollars.

Whatever the choice is.... It probably won't leak. I'm advocating the peace of mind and the preventative part of it, especially for the cost of the seal.

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