leaking th400

[Mark Ugrich]

Fluid level cold should be at “add 1 pint” ATF will expand as it heats up.

[richie 2]

1 1/2" ...full mark to dipstick end.

[Mark Ugrich]

Are you using the oem dipstick and tube or an aftermarket ? Even with a deep pan I believe the fluid level should be below the pan rail. If it’s an aftermarket dipstick try draining the pan so the oil level shows about 1/4 up the dipstick cold. Then go for a test drive heat cycle the trans and recheck to see if the oil level is at full when hot.

[richie 2]

we originally had a fancy milodon unit. i thought it was the leak source, went back to the factory piece. will get it sorted out and go back to fancy...

[richie 2]

pan manufacturer says fill to the factory full mark...WTF... the flex seal idea is sounding better adger...

[Mark Ruset]

Before you start throwing parts at the transmission you really need to locate the source of the leak. My days as a GM tech when I had a complaint of a transmission leak, I cleaned the entire surface areas with brake clean and then used air to make sure it was completely dry. Next I used spray tracing powder and sprayed the entire area., in a short time you should be able to see the powder turning a pinkish color at the source of the leak. It may be as simple as transmission fluid leaking around the front pump cover bolts that would make it look like a pan rail leak.

[Mark Ugrich]

Originally Posted by richie 2

pan manufacturer says fill to the factory full mark...WTF... the flex seal idea is sounding better adger...

I’d say the manufacturer is wrong. In 40 years as a tech, I’ve never started a trans with the level at the full mark.

[richie 2]

with the pan off, dipstick in, the full mark is higher than the trans/pan surface. the modulator valve bore is right there too....sure seems to be seeping out there. the valve and o/ring fit feels sloppy. measured it all up and installed theres not much crush on the o/ring, .020" roughly...

[Tom Goldman]

Definitely run the fluid level at the add mark.
Another area I've had issues with lately is the shift shaft seal .
It appears the newer seals are not as tight on the shaft as ones I had from old kits.
My solution has been to machine a groove in the shift shaft and install an o ring .

[Lenny5160]

Originally Posted by Tom Goldman

Definitely run the fluid level at the add mark.
Another area I've had issues with lately is the shift shaft seal .
It appears the newer seals are not as tight on the shaft as ones I had from old kits.
My solution has been to machine a groove in the shift shaft and install an o ring .

That's interesting. I was just laying under my car last night after installing the engine and trans (glide) over the weekend, and noticed some fluid on the end of the shift shaft which I've not noticed before.