Topic: C4 / C6 Transmission Fluid Discharge

[Angela]

I'm sure this topic has been discussed previously... in fact, I've probably raised the thread in the past. However, I've never figured out why the following happens and how to stop it. it happened again, I'm frustrated and looking for a solution.

I've been in the process of iteratively trying to get the fluid level in my C6 ('67 390 SanJose application) correct... and I thought I was pretty close to getting it correct when the engine and fluid was warm. The trans seemed to shift properly in the garage and driveway (keep in mind I have yet to actually drive the car as the decade-plus restoration continues).

But...

Then one evening I walked by the car and noticed what appears to be a couple quarts of transmission fluid all over the concrete underneath the car. Grrrrrrrr. Frustrating! I hadn't had time to play with the car in a couple weeks and given that the fluid appears to have eaten the concrete sealer off of my floor, I can only assume the fluid had spit-up a week or two prior. So, now I'm obviously low on fluid again and cannot understand why the transmission does this.

The tranny is one of only two items I farmed out to a professional (who has been rebuilding ford transmissions for 35 yrs). It's possible he did something wrong while rebuilding my trans, yet I know I'm not the only one to have experienced this issue.

This same car did the same thing several years ago and while I replenished the fluid, hadn't done this since. Why does this happen periodically? Is there a way to stop it?

And, most curiously (to me), if this happens now, I must assume it happened when these cars were new, right? Am I to believe that folks in the 60's just considered this behavior as normal?

Help? Comments?
 

[jmlay]

O-ring on the speedo gear or the o-ring on the shift lever would be my first guess. Pan gasket or the o-ring on the filler tube would be next. There is also a vent in the bell housing that may need to be sealed with your favorite sealer. There is also a vent on the top outside of the trans that could be leaking if overfilled.

[Murf]

You probably had converter drain from sitting.  The converter is normally full - and holds a lot of fluid by the way - and after sitting sometimes drains back into the transmission.  The transmission cannot hold that much fluid and the case becomes completely full and then begins to over flow out a little vent in the top.  There is a converter check valve that is supposed to prevent this.  Simply use your car now and then or if nothing else start it and this  will never occur again.

[cobrajetchris]

I hate to tell you my experience but I had my transmission rebuilt (professionally?) and it leaked from day one out the front seal. I put up with it for a year after exhausting all of the easy options as mentioned and then removed it and sent it to another transmission shop and they called me and showed me how the front seal bushing was scared and the clutches are burnt up with less than 500 miles on the rebuild. He felt the last rebuilder didn't get the main shaft centered and it caused the problem. No problems so far with this rebuild.