trans fluid out the vent

[turbodave231]

To start off, this is a Race only, T-400 trans with a Brake, 5000 stall converter. Two Step is set at 5500 to 5700 RPM. No problems with shifting or any operational problems for that matter.

I notice that the trans blows small amounts of fluid out the vent. I extended the vent line so I don't make a mess on top of the trans. It is definitely coming out the vent and not leaking elsewhere. Fluid level in the trans is at the normal level with engine running.

Is this normal and expected? Anybody running a catch can on the trans vent line? Are there any tranmission specific catch cans made for this purpose? I hate getting oil film on the bottom of the car. I'm thinking of designing a specific can for this purpose.

Dave

 

[Hacksaw]

4 things:

1. You using a trans cooler? Hot fluid will expand fast, especially with a high stall converter.

2. Are you using the stock filter? It's too restictive, get a screen type filter for a stock 400 pan.

3. The Full mark on the dip stick needs to be even to 1/8 of an inch below the pan rail. Check the fluid hot, it must never go above full.

4. There are other things, like a loose filter pick up o'ring, loose governor tubes, worn bushings, etc., that can cause internal spray leaks that cause foaming.

 

[turbodave231]

I understand the heat generated w/ high stall. Yes I'm using a plate style transcooler and not routing fluid thru the radiator trans cooler.

I'll triple check the fluid level hot to be sure. Good suggestion on loose components, I didn't build this trans, I bought it ready to go and I've never had a hint of problem with the unit so I've never had the pan off.

It's not like its throwing out huge amounts of fluid, heck my rear main leaks more than the trans vent. I'm just trying to clean up any leak I can. If a small catch can will stop the issue, that what i'll do.

 

[blackplague]

The best thing to do is either buy a catch can or make one, mount it to the frame {where you can find a location}, then run the line to it. I'm glad to hear that the trans has been, for the most part problem free. What happened to the converter that came with it? You may want connect to the vent, run the hose up to the top of the bell housing, then down to the catch can. :biggrin:

There will not be governor tubes on this trans.

 

[chris718]

Ive Seen This Many Times.if All Else Is Okay It Is Common For This To Happen When The Pump Faces Arent Flat.

 

[blackplague]

I will say that

both pump faces are flat in turbodave231 trans. Every 400 even if it's for stock purposes need at least the pump faces squared with a hone stone. I will agree with chris that if the pump faces are not flat some crazy stuff can happen! :biggrin:

 

[Hawaiian Turbo]

I heard that this is common for cars faster than 10.00's using the th-400. I installed a small catch can on the fire wall from the vent so it'll drain back into the trans.

 

[chris718]

I HAVE SOME GUYS RUNNING IN THE 7S WITH TH400S AND THIS IS NEVER A COMPLAINT.VERY STRANGE HOW IT IS COMMON FOR SOME