# 67 GTO TH400 Overflow



## Wyatt318 (Mar 9, 2020)

Recently changed out pan to a deeper pan. Problem I have is that when I fill it to the mark on the stick I get fluid coming out of overflow vent tube. With the extra fluid is it foaming when it gets hot or do I put less fluid in it.
Thanks


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## Sick467 (Oct 29, 2019)

I've only known an auto to puke out the vent tube when it's too full and/or over heated. If it's at the full mark (at running temps) and foaming...something else is wrong. The few American made auto transmissions that I have dealt with (Chevy 350TH, Pontiac 400TH, & the Ford AOD) all fill just above the pan gasket to be properly full. I would not put less fluid in it than that.

I'm no expert on transmissions, but I'd check that the filter is not setting too low and being choked by the bottom of the pan, or has come loose and fallen down.

Changing the stock pan to a higher capacity pan should not cause this issue so long as you changed the filter tube length so the filter sits lower and I'm not sure that would cause any issues if you did not.


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## BLK69JUDGE (Jun 10, 2010)

x2

I'm no expert on transmissions, but I'd check that the filter is not setting too low and being choked by the bottom of the pan, or has come loose and fallen down.


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## An0maly_76 (Dec 25, 2021)

Foaming could be a factor, but just a thought -- fluids expand when hot. More fluid = more expansion when hot, which could also be a factor, in which case less fluid and only checking when hot could help. But in a nod to the remark of overheating, is the stock radiator trans cooler known to be good? Might not be a bad idea to install an auxiliary trans fluid cooler, particularly if this car sees a lot of low-speed / city / stop-and-go driving, or is driven aggressively.


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