TH400 Leaking Fluid

[DAN76]

I've just pulled my 1965 Delta 88 out from storage and found a hefty pool of tranny fluid on the floor. As far as I knew there were no big leaks when I put it away so i'm hoping it's just a small drip that's accumulated over the long period of storage time.

I've never worked on an autobox before... Any suggestions?

[Oldsmaniac]

Try to identify exact source. Commonly the bottom pan gasket weeps and the pan bolts can be tightened or gasket replaced if its hard and brittle. Try cleaning the area with solvent and drying everything. This will also help to pinpoint exact area of the leak. There is a seal at tailshaft, front shaft, and where shift linkage enters the trans. Sometimes the dipstick tube at trans body will leak as well.

[joe_padavano]

Couple of thoughts come to mind. First, was the trans stored by simply sitting on the floor? Is it possible that the trans pan may have rusted from contact with concrete? I've had metal gallon containers of lacquer thinner rust out after sitting on the garage floor. Second, did you have a plug in the tailhousing? Was the converter in place? The driveshaft yoke and converter complete the seal at the input and output shafts. Without them, fluid can wick out or even spill out if the trans is tilted at all. Is it possible that water got into the pan and caused the fluid level to go up? This could have been condensation as well as rain. Finally, as noted above, it's not unusual for the trans fluid to wick out the pan (or other) gasket. The gaskets and seals will dry out over time.

[Bluevista]

Both mine do that if they're long term stored, no big deal. Since I heated my garage they both stopped doing it?
Those little drips do turn into big puddles and that stuff tends to spreads out pretty good.

[d2_willys]

Originally Posted by joe_padavano

Couple of thoughts come to mind. First, was the trans stored by simply sitting on the floor? Is it possible that the trans pan may have rusted from contact with concrete? I've had metal gallon containers of lacquer thinner rust out after sitting on the garage floor. Second, did you have a plug in the tailhousing? Was the converter in place? The driveshaft yoke and converter complete the seal at the input and output shafts. Without them, fluid can wick out or even spill out if the trans is tilted at all. Is it possible that water got into the pan and caused the fluid level to go up? This could have been condensation as well as rain. Finally, as noted above, it's not unusual for the trans fluid to wick out the pan (or other) gasket. The gaskets and seals will dry out over time.

Joe: From what I read, he said he pulled his Delta 88 out of storage. I think he meant the whole car, so the transmission is in the car.

Could the problem be converter draining back along with dipstick leaking, and or oil pan? I would start by cleaning off the oil pan and checking the bolts for tightness. Snug them up with a 1/4 inch ratchet drive and see what happens. Put some white cardboard down under the transmission and let it sit overnight, it will point you in the right direction of the leak.

[joe_padavano]

Originally Posted by d2_willys

Joe: From what I read, he said he pulled his Delta 88 out of storage. I think he meant the whole car, so the transmission is in the car.

DOH! That's what I get for not reading carefully...

[OLD SKL 69]

Also look at the modulator seal on the right side, electric kick-down switch and speedo seal on the left side. They are all "O" ring seals that will dry out from sitting and shrink thus leaking fluid. Also, they can all appear to be the pan gasket since they will leak down to that area. Wipe those areas clean and then recheck.

[DAN76]

Thanks fellas, i'll let you know how i get on!

[Techmaven]

Cool..You saved me from starting a new topic. My 67 88 TH400 did the same thing over the winter!

[Oldwolf]

Originally Posted by joe_padavano

Couple of thoughts come to mind. First, was the trans stored by simply sitting on the floor? Is it possible that the trans pan may have rusted from contact with concrete? I've had metal gallon containers of lacquer thinner rust out after sitting on the garage floor. Second, did you have a plug in the tailhousing? Was the converter in place? The driveshaft yoke and converter complete the seal at the input and output shafts. Without them, fluid can wick out or even spill out if the trans is tilted at all. Is it possible that water got into the pan and caused the fluid level to go up? This could have been condensation as well as rain. Finally, as noted above, it's not unusual for the trans fluid to wick out the pan (or other) gasket. The gaskets and seals will dry out over time.

When the car stands still for months, the oil level in the pan rice above the gasket and up in the oil dippstick pipe. If the O-ring is bad or the oil dippstick pipe is bent in the transmission mounting hole, you will have a constant leak until the oil level is under the O-ring. I think there is a higher level of oil in the turbine after a drive that pours down to the pan and constantly rise the oil level in the pan. I have two cars with exactly this problem, Big leak during the storage over the winter. Check the O-ring seal.