93' 850 with a slipping transmission after fluid flush

[93' 850GLT]

Tranny Troubles

I had the fluid changed at a shop soon after I bought the car with around 90k on it. Everything worked fine for a couple years with the exception of the dreaded flashing arrow if I put the car in 1st or 2nd grear and occationally it would start in 3rd gear. Other than these minor issues the car has been great!!

The car now has 120k miles and the fluid was looking dark, smelled a little burnt and the tranny would shutter slightly when starting from a stand still. I figured it was time to flush the tranny again. This time I did it myself, I used Pennzoil Dexron-III/Mercon ATF.

I followed the Hayes manual which only recomended 2 cycles of flushing and refilling. The fluid color was still a little off, and I felt I should have kept going, but I fugured they know better than I do. So, I cheched the level and road tested the car. The shutter was gone and even the arrow didn't flash when I went through the gears during the fluid level check procedure. However, after 15-20 minutes of driving the transmission started to slip so bad I almost didn't make it home. After allowing it to cool off, it functioned perfectly, until it heated up.

Ok, now this is when I found this site. Appearently, others have repeated the flush cycles until the fluid is like new. So, back out to the garage and more flushing. I ran about 11 quarts through it before it was pristine. Checked the level and this time I stuck close to home for the road test. Unfortunatly, the slipping appeared again after 15-20 minutes?!?!

Please Help!!!!

[White850Turbo]

The stock radiator has a section built into it to cool the transmission fluid. It sounds as if this section of the radiator is not functioning correctly for whatever reason or the flush caused deposits sealing the internals to be flushed out, thus sending the transmission in to a state of "shock" per se.

On another note, you should be running synthetic ATF. I know it's expensive, but it runs WAY cooler than dino-based ATF and has superior friction modifiers. That could be something you may want to take a look at.

[tina]

Did you ever have the PNP switch replaced? Sounds like that is the problem to me, probably nothing to do with your flush.