Transmission line check valves

[AR67GTX]

Who has actually installed one of these and did it work to prevent torque converter drainback. My rebuilt 727 is doing good and seems leak free but despite the new converter, replacement of bushings, seals, rings and valve body mods, it still leaks down over night. Right now the oil is 1 pint low when idling hot in neutral. When I check it cold the next morning it appears to be about 2 quarts over filled on the dip stick. That's a bunch of oil stacking up in the transmission case just looking for a way to leak out. So do these valves actually work and where can I find one?

 

[AR67GTX]

Anyone?

 

[AMX364]

Show us a picture or link might help. This is a aftermarket valve?

 

[miller]

Sorry...can't comment on check valves.
But, the readings your getting on the stick sounds pretty normal.

 

[AR67GTX]

Show us a picture or link might help. This is a aftermarket valve?

That's part of what I'm trying to find out - and then also does it work. Sonnax has a custom regulator valve for the valve body.

http://www.sonnax.com/parts/1842-lube-regulated-pressure-regulator-valve

But this does nothing to cure drain back - it only allows filling the converter in park. They also have some good tech sheets on the subject.

http://www.sonnax.com/tech_resources/188-the-cure-for-the-common-chrysler-rwd-cold

Apparently it's not only an inconvenience to idle the car in park while it slowly refills the converter - but doing so can create a lot of internal wear and possibly failure. So starting in neutral or immediately shifting to neutral is important if the transmission drains back.

But someone here posted last winter about installing a check valve in the return line from the cooler and swore it worked to prevent or slow drainback. I guess I may have to search some more for the thread.

 

[AR67GTX]

Well I found it pretty quick this time - just didn't go back far enough.
http://www.forbbodiesonly.com/moparforum/threads/best-source-for-a-torqueflite-re-seal-kit.121866/

Moparwacko and snakeoil24 discussed the valve. But then I noticed that Doug chimed in and didn't recommend them so that puts a damper on that. Guess I'll stick with neutral starts. At least nothing seems to be leaking for now. I guess a leak free TF is a rare thing.

 

[miller]

Don't remember...didn't you put a shift kit in it? Could be part of the deal.

 

[toolmanmike]

That's part of what I'm trying to find out - and then also does it work. Sonnax has a custom regulator valve for the valve body.

http://www.sonnax.com/parts/1842-lube-regulated-pressure-regulator-valve

But this does nothing to cure drain back - it only allows filling the converter in park. They also have some good tech sheets on the subject.

http://www.sonnax.com/tech_resources/188-the-cure-for-the-common-chrysler-rwd-cold

Apparently it's not only an inconvenience to idle the car in park while it slowly refills the converter - but doing so can create a lot of internal wear and possibly failure. So starting in neutral or immediately shifting to neutral is important if the transmission drains back.

But someone here posted last winter about installing a check valve in the return line from the cooler and swore it worked to prevent or slow drainback. I guess I may have to search some more for the thread.

Thanks for the info. Tmm

 

[AR67GTX]

Don't remember...didn't you put a shift kit in it? Could be part of the deal.

Yes - I did, a TF1 TransGo kit. It was actually advertised to help minimize the symptoms of drain back as part of the deal but I'm not sure I see how it could do that. See advertisement

http://www.transgo.com/products.php?product_id=78&pageactionprev=viewpricelist&category_id=&keyword=

I did not install the full manual control feature of the kit but I doubt that would affect the drainback issue.

Basically my symptoms are unchanged since the rebuild. I probably should have installed their NoYoYo kit (something like that) that results in full line pressure in park to fill the converter.

 

[dvw]

The factory went to using small inline filters in trucks. When they plug up, and they do, the return line from the cooler is the lube circuit. Wear from filling the converter on startup? I call BS. If there was a wear problem these transmissions would have been upgrade by the factory many years ago. Who cares if the converter feels loose on the first drive away?
Doug

 

[toolmanmike]

I wonder if it more about the pump bushing wear problem? My 70 does it. I have 2 96 Dakota pick ups. One does it and the other one doesn't. A simple return line check valve might be a better option.

 

[miller]

Yup, took a look. With all the different 'mods' done on the 727s, tossing in the differences in year models, really hard to say. Only 'kit' I've ever installed, was a B&M, 35-40 years ago! All it did, was firm up the shifts.
Seems that some 'fixes', adds to problems at other points. Could be something simple, like spring pressure on the valve too light, or something totally different.
Easily understand the frustration!

 

[AR67GTX]

Well, after spending the last 45 minutes pouring over the fluid and control diagrams in Munroe's book I have to say that trying to find a universal fix for TC drain back is probably and exercise in futility. It could be leaking down on the converter exit side, on the converter feed side, though the regulator valve, through the manual valve, through the accumulator, past some of the sealing rings - just about anywhere. Since I have a complete new TC, new front hub bushings, new sealing rings, etc, I had hoped the condition would be improved but looks like it's more complicated than that.

Thanks

 

[oldbee]

I wouldn't worry about it, the check valve thing in cooling line worries me more(if it blocks the flow)