Rear main seal

91 bronco 351w/E4OD
Does anyone know for SURE if a 91 windsor has 1 or 2 piece seal? I tried to look the part up and depending on who you try to get it from, some offer a 1 piece, some offer a 2piece and some places offered both. I even called 2 dealerships and got 2 different answers. If anyone has done one and knows for sure please let me know. If its a 2 it will be Saturdays project. If it is a 1 it will have to wait a couple weeks untill I have a whole weekend free. Thanks...


Staff member
There may not be a "for sure" answer; I found that Ford is pretty wild about documenting when they made mid-year production changes. Don't rely on the "build date" off of the door-jam label, it means nothing.
Thanks, Bill. I guess there is only one way to find out. Geeeeesh. There is already a little spot on the driveway I guess 2 more weeks wont matter. Thanks again, Bill


I'm The Decider
Are you sure its the rear main seal leaking?The oil pan gasket on that vintage Ford will leak and it will appear its the rear main seal leaking.
Yeah it is definitely the rear main. I am hoping it is a 2 piece. I am thinking I can get the pan out the way enough to get to the rear main cap. Either way, I have to get it done. I just think it is crazy that Ford doesnt even know whats inside there. Its like unwrapping a Christmas present to see whats inside lol
Had the TH-400 off my 454 CID engine and the flex plate, spent five minutes staring that that rear main bearing seal. If there was ever a time to change it, now is the time. It looked brand new, not a drop of oil anywhere, so I left it.

About two months later saw drops of engine oil dripping out of the flywheel cover, since the AT was completely rebuilt, red stuff anyway, removed that cover, definitely was coming from the rear engine seal. Said a couple of nasty words. But instead of removing that transmission again, dropped in a bottle of Lucas Engine Oil Stop Leak. Hasn't leaked a drop since and that was like over four years ago.

Didn't get paid from Lucas for this statement, but sure worth a try.

1978-1949 = 29 years, that is how long I put up with GM rope seal leaks, so you can kind of get use to it. Got one of those Chinese finger pulling tools, replaced the seal, even tried RTV between the halves, no luck, 5K miles down the road, poured out oil again. Noticed it really poured out quick until it hit that add oil line, so just left the oil level about a 1/32nd inch above that line. In theory at least, don't have to add a quart until that oil level hits that line. But still lived for years with a large piece of cardboard on my driveway floor.

Just keeping that oil slightly above that add oil line may even work for a Ford.

Rockauto shows a one piece Fel-Pro seal,

This must be an improved replacement, but also list a rope seal, so guess you won't know what you have until you look at it.

That Lucas AT stop leak also got me home with my motorhome, was 456 miles from home when that front seal gave out, poured AT fluid all over the place. On a 4th of July weekend, only thing I could find open was an Autozone store, purchased six bottles of it and a case of AT fluild. Stopped every 50 miles with some very tense driving. It didn't stop that leak, but it got me home. That made me happy.
Nick, I hear ya on the do it while your there staring at it thing. I am thinking about throwing a front pump seal at it while I am there just for that reason.
I am not muck on "snake oils" but Lucas is good stuff. I had an old 727 that had some slipping issues even after band adjustment. Two bottles of Lucas ATF fixed it right up. Drove it another 50k. As far as I know it is still running.
I am sure the guy that was behind your RV on the way home appreciated that. You should have charged him for "rust proofing" his car lol