sittnlo

Hey All,

I recently rebuilt my TH350, everything appears to work fine except for a mystery leak out of the dipstick/fill tube. The fluid is running out of the top of the tube.

The fluid level appears to be correct (checked with motor running). I did install a new pan, but it doesn't appear to be any different than the original. The pan could be shallow, is there anyway to check to make sure that I am getting an accurate reading on the dipstick?

The breather was checked before reassembly and wasn't blocked. Any easy way to make sure this passage is still clear of debris?

I was thinking this may have been a heat issue, but sunday the car was moved a few feet and the fluid started flowing out of the top of the dipstick tube.

The strange thing is it does this randomly, I drove the car all last weekend and didn't have a single leak, but moving it a few feet and it leaks like crazy.

The first time this happened was when I moved it a short distance as well.

Any ideas???

Thanks,

-Chris

dannyman

Sounds like the gasket at the pump/vent tube must have moved or was installed upside down during re-assembly.

Teardown and visual to confirm.

sittnlo

Wouldn't installing the gasket incorrectly cause a constant leak, not just a random one?

jimvette999

The only thing that comes to mind is an internal pressure leak. Since the end of the tube is submerged, excessive internal pressure could push fluid out the tube rather than the vent which is not submerged. I would check the valve body bolts and if not that then lip seal/seals or oil sealing ring/rings. The random leak may be attributed to a lower fluid level exposing the bottom of tube rather than being submerged in fluid. Let us know what you find. BTW, the trans should have held around 10-11 quarts with an empty converter after rebuild, 8-9 without a empty converter.

sittnlo

I'm thinking I'm going to try hooking a pressure gauge up to the vent tube, that would tell me the case pressure, as well as possibly let me know if the vent is blocked right?
Or would I want to hook a pressure gauge up to the trans cooler lines?

What would "normal" pressure be?

jimvette999

You checked the vent... there should be zero internal pressure. A thumb over the dipstick tube could perceive pressure. Trans. cooler lines are pressurized to min 70 psi and max 200 in Park & Neutral. I don't know what else could push fluid from the tube except malfunctioning internal pressure since the transmission case should not be pressurized. Forum member TimAT could possibly offer some insight.... suggest you PM him. He may have ran across this, I never have. You could simply remove the vent temporarilly to check if the vent is the problem.

sittnlo

Thanks for the help!

I'll send TimAT a PM.

All I have for a vent is a little plastic looking thing that sticks out of the top of the transmission, guessing this should probably have a line running from it? I haven't checked the vent yet, that was one of the first things I was going to check. I was thinking of hooking a brake bleeder up to it and seeing if I was able to tell that way if it was plugged up.

I won't be able to check this stuff until the weekend, I really hope I don't have to pull the trans again

jimvette999

The little plastic thing should have had a cap on it that will wiggle since it snaps over the tube. No hose required/used like that on a differential.

sittnlo

lol, sorry I mean I haven't checked it since this issue started. It was checked before assembly. If something got in there during rebuilding it, or after installing it I wouldn't know about it yet. I do have the little plastic thing, no cap on it though .

sittnlo

Well, I was able to check the breather, and it is not clogged at all.

The fluid level is below the checkered section. When I first started the car fluid started to rush out of the dipstick tube. Once it stopped, and the motor started to warm up, I added some fluid. Shut the car off, and started it back up, no fluid was coming from the dipstick tube.

Why would fluid come out when cold, but not when warm?

Suggestions???

Thanks,

-Chris

jpwetsch

Hello,
I'm having this same problem. Did you ever get it figured out?