Turbo 400 Coverter leakdown

[2buck]

I have a Turbo 400 in which the torque convertor will leak down in less than 24 hours. I changed the pan gasket, filter, the shift shaft seal, & the fluid a year ago & it was nice and clean.

I understand there is a check valve that is leaking.

Being a street rod it sits idle all winter & drips constantly.
Is there a way to easily fix this situation?

Thanks for the suggestions
Bucky

[Crosley.In.AZ]

there is no check valve in the pump , input shaft areas, unless somebody installed one..  

The oil flows out of the converter through the pump into the pan.  The clearances in the pump gears, bushings, input shaft , and the internals of the converter all play a part in the drain back.

the Converter you have,  do you know if it is a stall speed higher than an OEM unit?

[2buck]

The car has a switch pitch torque converter-stock stall speed in both modes as far as I can tell.
Bucky

[Crosley.In.AZ]

ah, now all the info comes out...  the switch pitch will tend to drain back faster.  I guess due to the design of the converter internally

[wayne petty]

just curious....

i would think the proper fit (not worn) of the input/turbine shaft bushings would reduce the drain back also... probably not totally eliminate the problem with extended storage times..


but..  since the ATF is coming out of the overflow..   i wonder if there is a way.. to construct some kind of catch can...  catch tube... just above the pan rail... with a TEE fitting into the filler tube.. or a threaded fitting into the top of the lower case clearing the valve body. or into the side of the pan..    a trapezoid shape perhaps..  or other.. so when the case fills with converter drain back..  the fluid can expand into this container instead of exiting the overflow tube..  when the engine starts .. the fluid level drops and the fluid in the container drains back into the transmission to maintain the proper level..   just an idea...



perhaps just extending the overflow /vent up the side of the dipstick then back down so it does not squirt upwards so any fluid has to go way up the dipstick to drain out..  it would have to have the loop perhaps 6 inches below the top of the filler tube..

[2buck]

Thanks guys. Now I know what I am up against. I'll check the transmission's breather & see if I can add a hose or devise that would extend that feature.

My transmission was professionally rebuilt and car has less than 40,000 miles so I ruled out internal wear problems.

I have a friend with a C4 & his trans was leaking down. He changed his dip stick's tube out for a Lokar unit with extra "O" rings to prevent leakage at that connection.

Thanks again
Bucky