turbo 400 causing engine front bearing failure?

Ok, i just pulled one of those pumps apart and i come to the conclusion that it's not a pressure relief valve but a cooler bypass valve.
So it's not a fix for too high converter charge pressure and the restrictor mod is still needed....

Marc.

 

Okay Marc

Your saying the cooler pressure has nothing to do with the converter pressure? I'm going to send this to my guy and I don't want to piss him off. I do appreciate the input and i want this trans to be right.

Gary

 

No, the oil first go's in to the converter then thru the cooler circuit and then to the lube circuit, if the cooler gets plugged the valve bypasses the cooler circuit so it goes directly to the lube circuit.
The problem with the thrust bearing is because of too much converter charge pressure and can get worse because of a restricted or plugged cooler or cooler lines
Without the restrictor mod the converter charge pressure will still be too high and the bypass valve will only make a difference if the cooler circuit gets plugged or restricted.


Marc

 

The only bearing failure that a automatic can cause in thrust bearing failure, usualy caused by convertor problems. A front bearing failure can never be caused by transmission problems

 

Marc

Just talked to my trans guy Jim. Agreed with you that it is a cooler relief valve and said he was thinking of doing the restrictor mod. too. Trying to cover all the bases here. Thanks for the input.

Gary

 

And ask him to also do the "full time lube mod". Like i said earlier in the thread the restriction limits lube oil, usualy this is not a problem but in a motorhome or in a towing application it's beter to include the full time lube mod.

ALWAYS use a restriction with the full time lube mod or it will be a crank killer turbo 400...

I tried to find a good picture about where and how to drill for the full time lube mod and this badly scanned magazine article is the only thing i could find
http://www.bdub.net/tranny/TH400SuperBeefing-text.pdf
(First picture)

Marc.

 

Lots of good explainations provided. So I won't get into that. I will say I have seen this in the pits with cars that do not have the lower converter cover in place while on stands and flashing the rpms in gear. You will actually see the ring gear on the flex plate move forward. There go the reason why it's a flex plate and not a flywheel for automatics.

 

Yes, what is being said here is true. I have 53F100 Ford with 302/331 stroker engine, TH 400 trans behind it via Advance Adapters kit. 8600 miles, engine thrust bearing gone. Local trans man, older man well experienced says too high converter/cooler line pressure places excessive forward thrust on convertor, causing engine thrust failure. I ran gauges in cooler lines before pulling motor and trans, up to 100 psi going on, way too much. My trans man says solution is as recommended here, modify orfice controlling oil flow/pressure to convertor.