I am about ready to rebuild my 289. Most shops I have talked with what to covert the block to a one piece rear main seal. Has any one switched over to this seal? Still not a guarantee it will not leak. Thanks for help!
I worked on a car with this conversion last year, the seal leaked. I replaced it with a new seal, just like the one that came off, used the recommended sealer/lube and it leaked after a few weeks.
The thing I don't like about the conversion is once it's done, there's no going back to original. The back of the block is machined and you're at the mercy of the skills of the machine shop doing this job and hope they don't screw something up... a bit risky, especially with an original VIN stamped block.
On the original 2 piece, I've had good luck using OEM seals, the later Ford ones had a C9ZZ service number.
I'm at a bit of a loss, this on the difficulties some have had reaping a successful outcome with the standard two-piece seal and then others whom just fear the idea of having to deal with it? :-\
Now, I'm also not the smartest guy, but I've never had any problems with these nor trepidation at the idea of them, and certainly not to the point of adopting the notion of recommending that "everyone" should convert (machine) their blocks to accept the one-piece design. :)
Scott.
I remember seeing this seal and wanting to try it. Haven't yet. A little pricey, but might be worth a shot.
https://www.saac.com/forum/index.php?topic=31328.msg224999#msg224999
the key to using the 2 part seal is not setting it on same plane at the main cap . rotate it 1/3 and ad a dab of rtv on the gap .
I've never gone as much as 1/3. I usually offset it about 1/2" and use Ultra black RTV on the joint. I find myself second guessing the lube on the crank. You want enough that the RTV doesn't stick to the crank and the seal is lubed at start up, but not so much that it affects the RTV.
I'm pretty anal about oil leaks if you haven't guessed.
Quote from: KR Convertible on April 23, 2026, 01:22:53 PMI remember seeing this seal and wanting to try it. Haven't yet. A little pricey, but might be worth a shot.
https://www.saac.com/forum/index.php?topic=31328.msg224999#msg224999
I have ordered four of these seals. Thus far, they have not come. I think I have waited about a year. I am being patient because this would be a game changer.
Quote from: 6s1432 on April 24, 2026, 11:07:42 AMQuote from: KR Convertible on April 23, 2026, 01:22:53 PMI remember seeing this seal and wanting to try it. Haven't yet. A little pricey, but might be worth a shot.
https://www.saac.com/forum/index.php?topic=31328.msg224999#msg224999
I have ordered four of these seals. Thus far, they have not come. I think I have waited about a year. I am being patient because this would be a game changer.
I'm wondering how you have waited about a year when they just announced it last November and they said it would probably be around March. Have you tried calling them to get a time line for when it will be available?
Roy
You're way more patient than I am. I thought they would be readily available by now. Just a good thing I don't have any projects going at the moment. Please keep us posted.
Quote from: KR Convertible on April 24, 2026, 09:25:53 AMI've never gone as much as 1/3. I usually offset it about 1/2" and use Ultra black RTV on the joint. I find myself second guessing the lube on the crank. You want enough that the RTV doesn't stick to the crank and the seal is lubed at start up, but not so much that it affects the RTV.
I'm pretty anal about oil leaks if you haven't guessed.
mine has been in the 68 this way since 1989 and does not leak
None of mine really leak. I would call it varying degrees of seepage. Rarely hits the floor. Just looking for better.
Tim Meyer is the guy who's having them made. His supplier is in the UK, have had couple of delays, they're currently saying May or June. I believe they've already made and sold them for the 351c. I'll try to find and post the link shortly. I believe they are around $80 each.
Dave
1-Piece Rear Main Seal-4.180″ OD https://share.google/zfKGN0RV9PoSsKnA5
Roy
The nice thing about the two piece is that, even if you have a seeper/leaker, it can be replaced in the car without removing the transmission.
Thank you all for your input. A lot to consider before doing it.