I have a C4 connected to a D300 in my flatfender. It uses an Advanced Adapters kit which specifies a vent hole in the top of the adapter housing. The vent is extended up the firewall. After the everything warms up fluid starts pumping out the vent hole when I get on the gas. It will do this until the tranny is out of fluid and no longer functions. Once it starts pumping it will continue for about 30 seconds even after the engine is turned off. It seems like fluid expansion to me. I am running a good oil cooler with it's own electric fan but would still not rule out overheating. Does anybody have any ideas?
~matt

how much engine tilt back do you have ? A pic might help ?

What is the transmission temperature? It sounds like it is overheating.
Edit: also could there be a plugged drain back hole in the adapter?

I don't have any pictures, the engine is tilted back some. I didn't think it would be a problem because wouldn't that mean that it would do that any time I went up a hill?

Not sure on the temp, that was my next step, I've got it all wired for a temp guage I just need to hook it up. The fluid coming out is pretty hot but won't bun your skin. The fluid is not at all burnt, looks new, smells new. BTW I'm using Type F fluid.

Didn't think of the drain back hole, could be a possiblility.

If it is pumping the fluid out till it no longer functions it is not an issue with heat expansion... Think about it.

Don't know why you need a vent in the adapter. Factory adapters don't vent and they don't leak. plug the vent hole. Drain the type f fluid that is for old fords like cruiseomatics not C4's you need dexron III fluid. this sounds like heat to me or the trans is over full.

Ditto on the fluid recomendation. You should be using Dexron/Mercon III+ not the F type. I also think it is not a fluid expansion/overfill issue, it would not drain until empty if this was the case- it would simply puke out the 'excess'.

On the fluid type, stay with the type F. Saying type F is for 'old' Fords is pretty funny.. maybe you need a history lesson on the C4/C5. Type F will make your trans shift a tad bit harder too.

I've never had a C4 puke fluid like that. I have had a manual valve body C4 puke some fluid at the top end of the quarter mile after I shut it down and shift neutral.. but that was just excess line pressure with nowhere to go. Is the valve body stock? If not, who put it together.. and did they get all the little bb's in the right places?

Don't know why you need a vent in the adapter. Factory adapters don't vent and they don't leak. plug the vent hole. Drain the type f fluid that is for old fords like cruiseomatics not C4's you need dexron III fluid. this sounds like heat to me or the trans is over full.

I tried plugging the hole, the tranny worked fine but started leaking out of somewhere else (don't know where yet but seems like it needs to vent). Advanced specifies a vent in the adapter but I'm not sure if the factory application had one. Does the Dextron III fluid handle heat better that Type F. What are the drawbacks of using it? The transmission was built by a knowledgable tranny shop. It's got extra clutches and a shift kit, it's not full manual but it shifts real firm. BTW I'm not running a kickdown cable right now. I'm gonna call the guy who built it and see if he has any ideas.