[bentwings]

I went through all the T-350 info on the search but didn't come up with this one.

I have about 20k on my rod. The trans was built about 9 years ago and I have been driving it 4 years. It has Kolen clutches and a heavy duty sprag assembly and a 3000 stall converter. There were a number of leaks along the way.

A new bullet and speedo gear set fixed that one. It has not leaked a drop from there.

New rear seal a couple years ago fixed that.

Lokar locking dip stick fixed that leak.

New steel o-ringed plug for the missing kick down cable fixed that one.

New pan gasket seems to have fixed that one.

The servo does not leak.

Vacuum modulator was replaced with another adjustable one....no leaks now.

Shifter shaft only leaks a drop or two once in a great while. Lokar shifter.

Cooler lines have new hoses last spring. I have triple clamps on each side of the lines from the trans to the cooler lines. 12 clamps total. This has been a major source of leaks of late.

Lines at the trans cooler are AN and do not leak. The cooler is a little above the trans pan and is in front of the radiator. There is no cooler in the rad.

The area between the pump and converter is dry. Even the converter is dry.

I just had the floor tunnel out and cleaned the top of the trans. Mostly dust and road dirt. The vent area was dry.

For the last 3 months there has not been a single drop of trans fluid or any fluid for that matter on the floor.

Then I come in last Sat at 6 AM to pick up the car for the morning breakfast and cruise and there is a huge puddle of trans fluid on the floor. I'd guess about 1 qt. 6 feet in diameter.

Now in the past when the guys at the shop push the car backwards I have noticed it will leak a little fluid. It seems around the pan. It will show a good qt over filled on the stick untill I start it, then it goes to about 1/2 low where I usually run it cold.

According to what they said Sat they only rolled it ahead so I could get out in the morning.

After the Sat run I parked it again in the same spot. Then about 8 hours later I pushed the car backwards about 30 feet and let it sit over night.
I came in about 12 hours later and dogone if it didn't leak a bunch again...this time into my cookie sheet.

Anybody got any idea what is going on??

[gearheadslife]

look at the front seal..

[Irelands child]

Sounds like my trials with a Ford C4 over the past 3 years

I'm on my 4th dipstick - 3 Lokar's, two of which were warranty replacements. Now have a locking Hughes which so far doesn't leak. You might want to again look at the Lokar dipstick. Those 0-rings(I 'assume' you have the 2 O-ring version, if not, Lokar will probably replace it under warranty). Those O-rings possibly could be replaced with the next larger cross section ring. After I put the Hughes dipstick in dragged out my spare C4 and checked the fit - it could be better.

Transmission pan bolts - conventional hex bolts leaked. Badly. I replaced them with washer head as well as some sealing washers. That leak is gone plus I torqued them to the low end of the spec.

Transmission pans - after four different brands(Ford OEM and SVT, TCI, and another, name now forgotten) ended up with a very nice aluminum Trick Flow that wont bend while being torqued to spec

Pan gaskets - cork now leaks. For many years, I used only cork and successfully. Now, it has to be fiber that wont disintegrate/spread out. I'm guessing that manufacturers are now using shredded cork and binding it with a glue of some sort rather then sheet material

I still have a very minor front seal leak - and that might just leak forever unless I pull the engine-transmission someday - then I still might not 'dig in'.

Good luck, and let us know

Dave W

[cobalt327]

I have had the exact same thing happen! Here's my story:

The car is a 1980 Malibu w/a TH350C. Has a little over 100K miles on the original tranny. I am the second owner (since 12K miles), so the history is irrefutable. It shifts perfectly, lock up works, no probs w/it ever- except the occasional huge leak.

With my car this only happens after it sits w/o driving it for a couple weeks. My GUESS is that the torque converter is somehow draining back into the tranny, causing the tranny to be overfilled. Then it leaks until the levels match.

Now all the tranny gurus can flame me for this being impossible.

BTW, I have a 1994 Sierra w/the 4L60. It does this same thing, and it too only dumps on me after sitting for a long time w/o being used.

If this is even possible, I don't know what the fix would be.

[rick 427]

cobalt327...it IS possible....it's called drainback....It occures when the pump bushing gets worn,or [more often] a rebuilt torque converter hub is slightly undersized...over a period of time,the fluid will drain back from the converter thru the hub/pump bushing area,thru the cooler line,and back into the trans,yet the front seal,as it can still have a good fit on the hub, will prevent the fluid from coming out the front of the trans. A tell tale sign is by an overfilled reading on the dipstick before start-up, and a normal level after start-up.I mostly saw this condition in the Chrysler products,for some strange reason,but,rarely, have seen it in others also. Mopar started putting anti-drainback valves in the oil return cooler line a while back on their trucks right from the factory. I've put those valves on a few older mopars with success,but never tried it on any other make car,since it happened so rarely,that the boss would just just have the guys pull the trans and have me change the pump bushing and converter,so I really can't say FOR SURE if it would be a fix for Ford/GM's, but I think I would find a flow chart,and if it looked like it would work, give it a try if the car was in my liftless garage at home.

[cobalt327]

This is the first time I have read any verification, and your description makes sense to me. Much appreciated.

[bentwings]

There is no doubt that I have "drain back". It's done this since I installed it. The converter is an aftermarket 3000 stall. ( unblown), they weren't very happy that I was using it in a supercharged car. It works very well and I don't abuse it often.

The Lokar dip stick is now suspect. I didn't know about the doube o-ring. Mine is an early one. I don't even think they were advertized when I got it. I'll clean everything up around it again and look more closely.

The pan gasket is a cork one. I did carefully torque the bolts. The self sealing bolts seem like a good idea. Have to check McMaster for some of these. I'm going to check the auto parts store for a solid pan gasket. We have a large trans supply house in town so I can check there too. I did check the pan bolts and they were all tight but it is a bit wet around the front of the gasket. I have a trans temp sender in the front of the pan but it seems ok. I need to look closer at it this week end.

Now this anti drain back valve in the cooler line....first, what is the part number and where can I get one??.

My cooler line are 3/8 dia and quite long even for a small car. The cooler is pretty large too so I would guess there is almost a qt of fluid in the system.

Thanks for the help guys.

[AutoGear]

I had a faulty reman torque converter do this to me once on a turbo 400 in a plow truck (late 80s/ early 90s C1500 'camper special' with helper springs and a V6). Ugh what a wonderfully reliable yet utterly awful POS. It just wouldn't die.

I forget the brand of reman TC; I had heard recently that there were 'lots' of people on the 'net having issues with the brand; I want to say Pro-King, but I'm not 100% as that could have been the brand that had replaced the faulty one