92slowmaro

iTrader: (22)

has anyone had problems with there th400 pressure regulator valve in the pump get stuck causing low line pressures? i lost 1,2,3 on a fresh transmission do to this sticking. just wondering if this is a common problem and what if any is the fix etc.

the trans checked out fine when i air checked the pistons for forward,direct, and intermediate.

382ssz28

iTrader: (24)

When you assembled in the first place was the valve moving freely? Did you take the pump apart and find the valve stuck? When you carefully remove the stuck valve, check to see if something was hanging the valve. If not, check and see if where the valve is stuck, the cast iron is "pinched down" like something fell on it. Check both sides of the stator where you found the valve stuck. If you bought the trans used, it might have had parts replaced that were purchased from a supplier that didn't take the best care when shelving the part or shipped the part. It will look very shiney where it was hanging up in the "lands". If this is a high HP car, I would replace the stator with another to make sure there are no lands out of round if pinched. If not, you can gently sand the area with some fine emery cloth-then red Scotchbrite like a hone, (with a port kit), testing the valve for freeness. The valve should fall under it's own weight with the stator in a position where the valve is north and south and the pump torque together. This might seem like alot of work, but you want to do this once.

You do not want to sand the sharp edges of the lands "dull" so to speak. You can "polish" the valve with the red Scotchbrite to remove fine scratches, but DO NOT dull the sharp edges. Dip the emery and Scotchbrite in mineral spirits often. It helps carry away the fine metal and you can see what you are sanding. Take just enough to make the valve free.

I assume you are doing this yourself and haven't built alot of trannies. Let us know what you found, with pics if possible. Hope this helps.

Good Luck.

92slowmaro

iTrader: (22)

yes i did the rebuild myself its my first th400, only other experience was building a few 4l60e's. i just got done cleaning the pump halves and about to reassemble the pump. ill check these things you have mentioned tomorrow and make sure all is good before final reassembly.

92slowmaro

iTrader: (22)

i checked it, the valve slides in and out freely so im not exactly sure what the problem was to begin with. trans goes back together this week in my free time and back in the car once i get the converter back from fti