1966 Mustang C4 Automatic Transmission Leak - Ford Mustang Forum
 
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post #1 of 14 (permalink) Old 03-22-2010 Thread Starter
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1966 Mustang C4 Automatic Transmission Leak

I took my C4 automatic transmission to be rebuilt back in December and got it back a lot sooner than I expected, so it sat in the garage until early March before it was installed. It was wrapped up with plastic wrap and sitting on a pallet, so nothing was able to get into or onto my newly rebuilt transmission. Since I've had it installed and have driven the car some, I've noticed that it looks like I'm leaking quite a bit of transmission fluid and it looks like it's leaking from the gasket around the pan. When I first noticed this, I jacked the car up to make sure that all of the bolts holding the pan on were tight. None of the approximately 8 bolts were even remotely tight, so I snugged them up, not putting too much on them because it looks like I have a cork gasket. Is there anything I can do to get this thing to stop leaking without dropping the pan (and subsequently all of the fluid) to replace the gasket? I'm contemplating taking it back to the shop that rebuilt the transmission for me and having them take a look at it, but then I don't want them to tell me that I torqued the bolts down too much and it was all my fault (I don't have a torque wrench or torque specs). Also, I have checked the auto. trans. fluid level while hot like the dipstick says and it seems like it is over filled. Could an over filled transmission be causing the excess to be squeezed out from anywhere possible, including the pan gasket?

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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post #2 of 14 (permalink) Old 03-22-2010
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The cork gasket most likely compressed over time since they initially installed it, they usually require retightening. The overfull issue would not cause the leak from the pan but should be at the correct level either way. When you tightened the bolts did the leak slow or stop?

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post #3 of 14 (permalink) Old 03-22-2010
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I purchased a cheap torque wrench from pep boys for $15 and checked it against a $300 model. It's accurate but it will have a short life span; hence the price. Don't know for sure but most trans. pan are torqued to about 13#'s. Could be the gasket, maybe your seals dried out.
I had same thing happen on a 350 trans. so I replaced pan gasket. Wish I had installed drain plug. Turns out the front seal was the leak.
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post #4 of 14 (permalink) Old 03-22-2010 Thread Starter
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Quote:
Originally Posted by Icerat View Post
The cork gasket most likely compressed over time since they initially installed it, they usually require retightening. The overfull issue would not cause the leak from the pan but should be at the correct level either way. When you tightened the bolts did the leak slow or stop?
The leak did not seem to slow or stop after I tightened the bolts. I'm thinking about crawling under the car again today and checking it out to see if I can see any other places that it could be leaking from.

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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post #5 of 14 (permalink) Old 03-24-2010
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on mine it seems that if i dont drive it to often the gaskets dry up and they start leaking but if i drive it every day they dont leak at all. i think it has to do with the cork gasket that gets dry with out oil
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post #6 of 14 (permalink) Old 03-25-2010
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if you havent fixed the leak yet heres some advice... check your dipstick tube it might not be in all the way, theres a o-ring on the end of the tube make sure its in good condition, push the dip stick tube in untill it snaps into place... if it still leaks you over torqued the bolts for the pan so no your not getting a good seal take it off and set in on the ground and see if it is uneven if so scrap it and buy a aluminum one the lip on them are thicker so its harder to bend and buy a rub gasket there way better than cork
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post #7 of 14 (permalink) Old 03-25-2010
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You've got some good advice here but I'm thinking there is also an overflow tube toward the rear of trans that also could leak if the trans is overfilled. I could be wrong it's been a while that I've seen one but it's something to look at.
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post #8 of 14 (permalink) Old 03-25-2010 Thread Starter
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I haven't fixed the leak yet and still haven't been able to get under the car to check everything out again because it SNOWED in Oklahoma in MARCH. Things are all dried up now, so I can pull the car out and get it on some jack stands and see if I can see anything obvious. I'll check out the dipstick issue and see if it is possibly not seated all the way. It seems as if the leak is coming from the middle or rear of the transmission somewhere because that is where the drips seem to "puddle". I'm kind of disappointed that the transmission place would put a cork gasket on this instead of a good quality rubber gasket on a $1000 rebuild. Guess everyone wants to save a penny where they can. Thanks for the input guys!

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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post #9 of 14 (permalink) Old 03-25-2010
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If I were you I would put the car on jackstands, get under it with a spray can of brake cleaner and spray it down to get all the tranny fluid off and clean the tranny. The brake cleaner dries fast and leaves no residue. Start it and get back under it while looking for your leak.
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post #10 of 14 (permalink) Old 03-29-2010 Thread Starter
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Okay I jacked the car up this weekend and took another look at my tranny. I tightened all the bolts on the pan again because the first time I did it, I didn't tighten them a whole lot. I snugged all of them up pretty good, but made sure not to wrench down on them too much and possibly screw up my cork gasket. While I was under the car, I noticed a few places where trans. fluid was possibly coming from. There was fluid on the gasket between the pan and the transmission. Also, there was a tiny bit under the transmission modulator valve. Another place that looked a little bit wet was at the gasket near the rear of the transmission where the transmission startes to taper down to where the drive shaft fits into it, it looked like the gasket was a little wet ONLY on the bottom side of the tranny. Finally, the cross brace that bolts under the transmission had quite a bit of fluid on it and was dripping from several locations, so I'm not sure if all of the places I mentioned were leaking or if it is just leaking from one place and blowing everywhere else when I drive it. After I tightened the bolts up this time, I put some paper towels under the car to see if it leaks anymore, and it seems like I only have one concentrated drip now, instead of several drips, so maybe I almost have it nailed down. I'll have to jack it up again soon to see where my one drip is coming from.

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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here is some good info on your transmission http://www.allfordmustangs.com/forum...-solution.html
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is your leak fixed. How much did your rebiuld cost???
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post #13 of 14 (permalink) Old 12-13-2011 Thread Starter
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Quote:
Originally Posted by jascal View Post
is your leak fixed. How much did your rebiuld cost???
Oh boy it's been a long time and I forgot to update. The transmission modulator valve was leaking for one thing and the dipstick tube was leaking also. Apparently all that had to be done was re-seat and tighten the modulator valve and for the dipstick tube, it just needed to be pushed in better/further. The leak is totally gone now. When I had it rebuilt, it cost me roughly $1000, but the insides of my transmission were trashed. It had water and rusted parts inside. I'm surprised it still shifted gears!

I finally got the engine and transmission rebuilt!
1966 Mustang
289 c.i., 2V carb
Automatic C4 transmission
Griffin 2 core aluminum radiator
Hedman headers
Dual Flowmaster 50 Series Delta mufflers
Ultra thin Spal 14" electric fan
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I want to find a new torque wrench , My request is accurate and durable; where i can get it?install my cool car accessories.
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