C4 Purged ATF or Mystery Leak

[TX-ZACH]

Bronco is back after a fresh 351w install and in the process of breaking in and road testing working out a few kinks. I made a trip to town and drove about 30 miles on that trip. When I got home and inspected I had ATF from front of main seal to the rear diff. It looked like someone squirted the underneath with a hose. I checked the fluid level and it was down a quart. I suspect when I engaged the motor and did a hard shift from 1st to 2nd thats when it happened otherwise no leaks just easy cruising around.

I filled the fluid and wiped it all down underneath trying to find a leak. I can find no leaks and a bit gun shy to try to engage a hard shift at this point. I am wondering if I have a purge valve issue. I am about 300 miles into the break in and maybe I'll try a hard shift again soon. Any tips appreciated.

 

[ared77]

I remember there was an issue in the Mustang community where some c4's were puking fluid out the dip stick tube. Off the top of my head I can't remember the exact cause but I'll try to find it and add more info.

 

[Jambi]

I am having the same problem, so I'll be curious to see what responses come in.

 

[ared77]

I've been out in the garage trying to find the paper copy of what I was talking about that I'd printed out and saved. I know it's out there because I save everything. But that's part of my problem, too much to be able to quickly find something some times.

Anyway, I did an internet search and found some similar things. Here is one example -


"The internal C4 anti-drainback valves aren't too reliable after 50+ years. Since the fluid is a direct feed through the cooler you can install a one way check valve on one of your cooler lines. They make and sell valves just for this. You can use it on either cooler line just make sure it's in the correct orientation for fluid flow.
Here's one. Amazon.com: Teckpak CR1012 Drain Back Valve, 5/16" (Installs: Automotive"

Maybe this will get you started and if I find what I was originally looking for I'll add it . Good luck

 

[TX-ZACH]

Nice find. Lets hope its as easy as that.

 

[surfer-b]

make sure the vent is not clogged

 

[El Kabong]

Did you shift into neutral while driving? I had a c4 spit out fluid after doing that once.

 

[brncofinatic]

Did you check the modulator? Do you have the plate which hold it inplace installed. I had that problem. Might check that.

 

[AZ69EB]

C4 pump can be in bypass mode. This stops trans fluid from going through the lines to the trans cooler. Trans gets hot and pukes fluid out the dipstick tube.

 

[TX-ZACH]

I will inspect the modulator and plate. I am unsure about the bypass mode as this Bronco is new to me. So far I have driven a little over 100 miles and the issue has not replicated. Other than hard shifts going into gear due to the current carb idle adjustments everything seems to be in working order.

Right now I have a slight lean stumble (idle to 1/4 throttle) and idle is set a little high until I figure out increasing the accelerator pump or power valve. With this roller cam set up she needs to warm up a bit and need the high idle so it does not die. Once at running temp she really wants to eat.

 

[TX-ZACH]

This just happened again. This has happened (3) times in 5000 miles. Different scenarios freeway driving or country roads. It purges about .5qt from somewhere on top of the unit or not visible from looking from under it, get all over everything underneath. Like its from high pressure. Definitely not the dipstick, but residual near rear main. Once I clean up, nothing continues to leak even after a road test.

Bazaar...

 

[Viperwolf1]

Sounds like it's coming from the vent, top of the adapter, just behind the C4. Only 2 things will cause that to happen.
1) It's over-filled. Full mark on stick is only used when it's really hot, like after a long drive. If it reads full before you've driven it it's too full. Wrong dipstick and/or tube can cause it to show incorrect level.
2) It's getting too hot. The fluid expands a lot when hot. Slipping clutches or converter can boil the fluid. Inadequate cooling is something to look for.

 

[TX-ZACH]

Good to know. I just filled it again to level while at cold idle. I will run it hot and check level again and remove if necessary.

 

[Rustytruck]

on my 1974 Bronco cold fill level it just reading on the very tip of the dipstick any more than that it goes over the full mark when hot and will puke fluid out the vent and you will see tranny fluid spots on the tailgate if your running at freeway speeds. if your running a tranny cooler make sure it is set right to hold fluid on shut off and not drain back to the pan when shutoff.

 

[TX-ZACH]

I guess at some point I will no longer be a rookie. After systems hot I was able to pull out 3/4qt to get level. I will roll it and test to see if it replicates after this adjustment. If it does, I will proceed to alter the cooler.

You guys are a national treasure.