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Discussion Starter #1 (Edited)
About 3 months ago I bought a used TH700R4, overhauled it, then put it into my big block '71. It shifted great but it wouldn't lock the torque converter. I drove it around for several days and around the 200 mile mark it suddenly started blowing oil out of the dip stick tube when I was pulling the 17 mile long 5% grade coming home.

I had put 23 pints of oil in it because that's the amount the shop manual called for for a fresh overhaul. I suspected the 23 pints was a misprint so I sucked out a quart of oil and tried it again. Same thing. It blew oil out of the dip stick tube just like it had done before. And as before it only puked oil out when I pulled the 17 mile long 5% grade coming home. So I sucked out another quart of oil and tried it again. Same thing. And by this time the oil had darkened a lot and now stunk; indicating it had been grossly overheated.

Frustrated, I decided to switch gears and look into my torque converter problem. When I pulled the oil pan down I was very surprised to see the oil filter came down with it. I pushed the filter back up into place but it just slid down again. A closer inspection revealed it's seal had lost all of it's tension. It's three outer ribs had totally collapsed as had the inner rib. I suspected the excessive heat had caused the damage to the seal and is why it had lost it's tension and loosened.

I set that filter aside, put a new one on, and replaced the oil (just 10 quarts this time). I got my torque converter lock-up working and was very relieved to see it had finally quit blowing oil out. But after about 200 miles it suddenly started blowing oil out just like it had done before. But I was lucky in one respect as I happened to pull over to the side of the road this time and checked the oil level. Even though I had only put 10 quarts in it it was showing about 3" overfilled. Huh? That made no sense whatsoever (at that time anyway).

After a lot of thought I came to the conclusion my torque converter had somehow drained it's contents into the pan and was the cause of the "overfilling". But why would it drain? Something had to be wrong with either the pump or the filter. As I had rebuilt my pump to minimum tolerance specifications I suspected the new filter's seal had failed just like the first one did. I pulled the oil pan off again and although the new filter didn't come down with the pan like it had done before it was definitely loose. I removed it and found it's seal was damaged just like the first one; the three outer ribs had collapsed as did the inner rib. Two filter seal failures in a row and in less than 500 miles.

I noticed the first filter had been made in China but the second filter had been made in America. So now I'm wondering if all of the filter manufacturers are using low-quality Chinese made seals. After taking some measurements I found I could easily replace the single multi-ribbed seal with three common 3/32" X 11/16" X 7/8" Viton o-rings stacked on top of each other. With the three o-rings on it it took about 5-6 times the amount of effort to shove my filter into place so there's no doubt of it sealing now.

As my new oil had also gotten grossly overheated (and stunk) I put 11 quarts of fresh oil in it and took my car on a 150 mile trip today. And when I pulled the long steep 5% grade coming home not one bit of oil got blown out this time. So I think my problem is finally solved. I e-mailed Dana Wilkes at Pro-Built transmissions and told him what I had been dealing with and what I did to permanently fix the problem. In my e-mail I told Dana the problem ONLY shows up when the transmission is at FULL operating temperature. As the pumps used in TH700R4's are such low volume pumps and are mounted about 6" above the bottom of the pan, it only takes a TINY bit of air leakage at the filter's seal to almost totally stop the pump from pumping. My pump was maintaining enough volume and pressure to keep the clutches and band engaged but that's all. It wasn't producing enough extra volume to keep the torque converter filled. So as the torque converter slowly drained the remaining oil in it (maybe 2-1/2 quarts?) got real hot.

So if you ever have oil suddenly start blowing out of your dip stick tube your filter's seal has probably failed. But the fix is real easy.
 

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You found a seal that will withstand the heat but why is the transmistion getting that hot. I could understand if you were towing heavy up a steep hill but these are fairly light cars. Did you smell the fluid after the seal fix?
 

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Discussion Starter #3
You found a seal that will withstand the heat but why is the transmistion getting that hot. I could understand if you were towing heavy up a steep hill but these are fairly light cars. Did you smell the fluid after the seal fix?

The oil got real hot because only 1/3rd to 1/2 of the converter was full. Normally oil continually circulates through the converter but when the pump starts sucking air the flow of incoming oil is drastically reduced. As the converter dumps it's oil into the pan, the pan overfills and then the spinning parts heats it up even more.
 

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Discussion Starter #5
and if it was sucking air, foaming probably also contributed to the increase in temp

I'm running 11 quarts in it right now and it appears the problem got solved by using the o-rings. Driving on flat ground was okay but the moment I got up the first 5 miles of the 5% grade coming home the problem started. I learned today this is something that has been happening to TH700R4's for some time as Chinese made seals are ending up on American made filters. The seals harden within just a few hundred miles then they lose their tension. Then the pump starts sucking air and the torque converter gets starved.
 
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