Front seal leaking on 904

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64physhy

64physhy

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The front seal in my transmission appears to be leaking. How hard is it to replace? Which way would be easier; removing the engine to replace it, or removing the transmission, or pull them together and separate them once I get them out? I'm getting tired of removing and installing engines on this car.
 
Are you certain that it's the front seal that's the problem ?

I've seen where the the torque converter galls the input shaft on V8-destined 904's , in early models ( c.1964 - c. 1970 ) ; this will cause the leak that you're talking about .

I certainly hope that I'm wrong ...

Have you tried Lucas Trans Treatment ? If the seal's shrunken , the Lucas snot will help soften it back up and at least s-l-o-w the leaking .

If you want to replace the seal , then maybe it's a good idea to yank the motor & trans combo , and replace the main seals on the motor as well .

Just my 2.7 cents .
 
Not sure. It's in my '74 Duster, but I'm not sure what year the transmission was originally from. It happens kind of randomly. The first couple times, the car had just been sitting for a few days, then all of the sudden dumped close to a pint overnight. That actually happened a couple times that way. Today, I moved it, and as I pulled it into a different spot, it left about a 3 foot long strip of fluid just as I was parking it. Both times it dumped while it was just sitting was when the weather got a little colder, which is why I was assuming it's the seal. I'll try the Lucas if it will keep me from needing to pull it. Thank you your 2.7 cents.
 
IMO it's far easier to pull just the trans. Double check everything real good cause there are several other places it can leak and run down the bellhousing.
 
I put some of the Lucas treatment in it. We'll see if that works, but as bad as it pisses out sometimes, I'm not counting on it. It's weird that it won't leak a drop for months, then all the sudden goes on the rag. My car must be a female.
 
I had similar problems all summer with my pump first then front seal.I ended up getting my driveshaft redone(was out of balance),which fixed my seal leaking issues.Good luck.
 
Are you certain it's the pump seal? Sounds more like the dipstick seal and the convertor draining back intermittantly. There's a valve in the valve body that is supposed to keep that from draining into the pan, but it almost always leaks a little. That allows (at times) the 4-5 extra qts of fluid in the convertor to drain into the pan, which places a bit more of a load on the dipstick tube O-ring. If it leaks while running, it's usually the pump seal. If it leaks while sitting, it may not be.
 
moper said:
Are you certain it's the pump seal? Sounds more like the dipstick seal and the convertor draining back intermittantly. There's a valve in the valve body that is supposed to keep that from draining into the pan, but it almost always leaks a little. That allows (at times) the 4-5 extra qts of fluid in the convertor to drain into the pan, which places a bit more of a load on the dipstick tube O-ring. If it leaks while running, it's usually the pump seal. If it leaks while sitting, it may not be.
Click to expand...

Well, it's coming from the inside front center of the bellhousing, so I'm pretty sure it's not the dipstick. I do think it has something to do with the converter draining, but it drains on my driveway, not into the pan.
 
Ok. I really need to get this fixed. I still haven't messed with it yet. If it is the converter, what's the fix? Hopefully, it's just the seal. That's what I'm thinking since it seems worse when it's cold out.
 
If it is just leaking from the vent hole, what's the cause? How'd you crack that bellhousing?
 
64physhy said:
If it is just leaking from the vent hole, what's the cause? How'd you crack that bellhousing?
Click to expand...
Bent d.shaft vibrating at 121mph LOL.Maybe foaming up,bubbles??I,m not sure what would cause it.Fishy68(Tracy)would know way more about the 904,s than me.
 
Oh. Well, it's not from being hot because it happens while it's just sitting in the driveway. Not overfilled either. The driveshaft needing balanced is a possibility, even though it's a new driveshaft that's supposedly balanced.
 
If it mainly leaks while sitting it's likely a front seal or pump perimeter o-ring. While you have it apart it might be a good idea to check the converter too just in case.
 
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