leaky seals
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Elder User
Joined: Jun 2010
Posts: 934
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From: Sterling, Virginia
leaky seals
Hi all, I was not experienced to know that when my engine and tranny came back from being rebuilt, I should have put fluid in them right away. As a result, they sat dry for too long. The seals must have dried out because now that it's running, I have leaks in both the engine and tranny. As best I can see tranny leak is comming out of the shifter shaft and the engine leaks are in front and out back. Probably the main seals. OK so my question is what can I do short of pulling the drive train to have the seals replaced ? It doesn't affect performance but I don't like the leaks. 
Fleet Owner
Joined: Jul 2004
Posts: 27,283
Likes: 1,046
From: NM
What specific engine/trans are we talking about? I tend to agree with Ray, get some run time on it, see if it goes away.
If it's a modern engine with rubber lip seals on the crank, there is no reason for it to leak just because it sat. The rebuilder would have (should have) wiped all seals with oil during assembly. I'm assuming it sat for months, not years? New cars sit on the dealers' lots for months without problems. Seals are made of a mix of quality polymers like teflon and urethanes that are very resistant to taking a set or decaying. Is the rebuilder telling you it's your fault?
One of my cars sat for 7 years without ever running before I bought it, and it had 88k miles on it when parked. Its rear main leaked when I started it up and never got better, but that was the only seal that leaked at all. I think 7 years is a big difference from what I'd assume is a year at most.
If it's a modern engine with rubber lip seals on the crank, there is no reason for it to leak just because it sat. The rebuilder would have (should have) wiped all seals with oil during assembly. I'm assuming it sat for months, not years? New cars sit on the dealers' lots for months without problems. Seals are made of a mix of quality polymers like teflon and urethanes that are very resistant to taking a set or decaying. Is the rebuilder telling you it's your fault?
One of my cars sat for 7 years without ever running before I bought it, and it had 88k miles on it when parked. Its rear main leaked when I started it up and never got better, but that was the only seal that leaked at all. I think 7 years is a big difference from what I'd assume is a year at most.
Senior User
Joined: Sep 2011
Posts: 135
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From: Metro Atlanta
When I bought my 56 F100 last year it had sat up allot since the build and the AOD leaked a little at the front seal. One bottle of Lucas Transmission Fluid Conditioner and after about 100 miles or so the leak stopped. 
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Elder User
Joined: Jun 2010
Posts: 934
Likes: 2
From: Sterling, Virginia
It's a 289 with a C4 tranny. I have about 12,000 miles on the drivetrain so I don't think it's going away. I have tried Lucas and I can't see any improvement. It's not a big leak but just enough to make a mess. It sat for monnths not years. I fault myself for not knowing, but I think the "pros" should have told me. But anyway is there any way of replacing the seals without pulling the engine and tranny?
Tuned
Joined: Jan 2003
Posts: 486
Likes: 66
From: South Carolina
I just changed the front crank seal on my 460. I also replaced the rear seal on the tranny and the shift shaft seals (c-6). Truck only has 3,000 miles on it since the rebuild/restore 5 years ago, but you do what you gotta do.
Here is an article on the shift shaft seal.(pretty easy to do)
1965 Mustang c-4 transmission manual control lever seal replacement Page1 - Modified Mustangs & Fords Forums at Modified Mustangs & Fords Magazine
Here is an article on the shift shaft seal.(pretty easy to do)
1965 Mustang c-4 transmission manual control lever seal replacement Page1 - Modified Mustangs & Fords Forums at Modified Mustangs & Fords Magazine
Fleet Owner
Joined: Jul 2004
Posts: 27,283
Likes: 1,046
From: NM
Have you put 12k miles on the engine/trans since the rebuild? What I mean is, has it been leaking all that time? Or did you run it, then it sat, now you're running it again?
No way the seals should be leaking from sitting for months. Like I said, new cars sit on the lot that long.
No way the seals should be leaking from sitting for months. Like I said, new cars sit on the lot that long.
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Logistics Pro
Joined: Apr 2010
Posts: 3,577
Likes: 29
From: Pekin, IL
I personally have never tried to replace the rope seals( that's what they are right?)with the engine in the vehicle. I HATE rope seals...they are a PITA.
I have replaced them with the motor out. If you don't hold your left ear just right, they can leak again. I should say you gotta pay attention to detail. Gotta check out the seal surface of the crank too. The rope seals will wear on them and create a narrowed surface. there are repair sleeves for that.
I am gonna stick my neck out and say it's better to pull it. Sorry...
Trying to do stuff like that on your back is not any fun. The seal half that is recessed up in the block at the rear main is tough to get out sometimes. Trying to get the new one in without tearing it up is about as tough.
Not what ya want to hear, I know.
Anybody...feel free to comment on this. pros or cons, agree or disagree?
I have replaced them with the motor out. If you don't hold your left ear just right, they can leak again. I should say you gotta pay attention to detail. Gotta check out the seal surface of the crank too. The rope seals will wear on them and create a narrowed surface. there are repair sleeves for that.
I am gonna stick my neck out and say it's better to pull it. Sorry...
Trying to do stuff like that on your back is not any fun. The seal half that is recessed up in the block at the rear main is tough to get out sometimes. Trying to get the new one in without tearing it up is about as tough.
Not what ya want to hear, I know.
Anybody...feel free to comment on this. pros or cons, agree or disagree?
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Thread Starter
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Elder User
Joined: Jun 2010
Posts: 934
Likes: 2
From: Sterling, Virginia
Thanks for the tips, guys. Yes it has 12,000 on the rebuilt motor and yes it's been leaking the whole time. I've cleaned up the mess on the chassis and as best I can tell it's the main seals and the shifter shaft. Thanks to purple55 on that link to fix the shifter shaft, I'm kind of clueless on transmissions so I may just take it to a shop and see if they can do it. Thanks all
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