Without that retaining groove, there's no way to get a seal. I'm surprised you didn't stop then and there when you saw there was no groove. Somehow, you have ended up with the wrong main cap. Until you replace the cap (and getting a precise fit is a PITA, ask me how I know) you have zero chance of getting a seal.

 

Ya know, I misread that post. I didn't see that the block is an older two-piece rear main style, while the cap is for a one-piece. Ignore my last post.

 

Well the engine its self is from an 85 Tunderbird. Whats the chance of me using the Main Cap off my old 289? Or do I need to order a new main cap?... I didn't stop because my desire to finish the repair convinced me that the pressure of the main cap pushing down would hold it in place.

 

You'll have to gauge it to see if it fits properly.

 

You cannot swap the main caps. Period. They are machined to the block. Do not swap the main caps.

I don't know what type of seal an 85 t-bird takes. I did a quick search on oreilly's for you. Most of the seals are 1 piece. They do offer a 2 piece. I am not sure what that is all about.

http://www.oreillyauto.com/site/c/se...ird&vi=1140163

Was the seal you removed a 2 piece? I am guessing so or otherwise you would have had a hell of a time removing it. While you were removing the seal did you rotate the crank to check for nicks on the sealing surface? Did you apply silicone where the 2 seal ends meet?

BTW, the photo in the link is of a 1 piece seal main cap.

If you did have a 1 piece, you would need to pull the engine or tranny to replace it.

 

That ship has sailed. Somebody already did. Now he has the wrong cap, and absolutely no way to get a seal.

Depends when the engine was made. Early engines were machined for a 2-piece rope seal, although almost everyone uses a 2-piece neoprene seal to replace them. Later engines are machined for a 1-piece seal. Totally different. His problem is he has the earlier rope-seal type block, and some fool put a later style main cap on it.

 

Who did the machine work when you rebuilt the motor? If they had the block annd cap then i would be wanting to have a talk with them about what happened and why it wasnt identified then that the cap as wrong.

 

The main cap is the original from the block. The engine came out of the Thunderbird, 60k original miles, driven by an old man, and straight into my hands. I made a judgment call to not send it to the machine shop because everything was super clean and the cross hatches were still on the cylinder walls. If I remember correctly there was a one piece main seal that I took off when I was rebuilding the engine but the rebuild kit that I got from www.northernautoparts.com was a two piece. My mechanic friend helping me said it didn't matter (he must not have noticed the main cap) so I installed the two piece seal that I just took out the other day.

The two piece shown on the oreilly website is the one I just put on.
I did not rotate the crank because I was in a hurry, a mistake I will not make again.
I did apply silicon where its supposed to be.
The entirety of fault with this problem belongs to me alone.

I am curious as to why I was able to drive this engine for 3 years on a two piece seal before it went out if its supposed to be a one piece. Anyway, I am headed out to get some pictures now. I will post them shortly.

 

Well I cant get any pictures that are worth snot. At least not until I get a chance to tear it back apart. From what I am gathering I will be pulling the engine or trany to fix this anyway... Now would be a nice time to have tourettes because then it would be normal to yell profanities at the top of my voice.

 

I'm thoroughly confused now. You originally said that the main cap had no retaining lip for a two-piece seal, indicating that it's designed for a one-piece seal. You also said the block itself DID have the lip, which would mean it's designed for a two-piece seal. This suggests the block and main cap are mismatched.

However, you said a) the block is from an '85 t-bird, and b) you think you pulled off a one-piece seal originally. An '85 t-bird 5.0 should have a one-piece seal, and you can't put a one-piece seal in a block designed for a two-piece seal. It just won't work. The other way around (a two-piece seal in a block/cap designed for a one-piece seal) will work, but it'll leak like a SOB.

Is it possible you're mistaken about the lip in the block? If it has no lip, it, like the cap, is designed for a one-piece seal. If that's the case, either of the two part #'s I provided will fix all of your problems.