Lost 3rd gear on my 87 chevy van

transmissions

#1

On a cold day one of the tranny lines that go to the radiator blew off and dumped 7 quarts of fluid on the road. My first hint that something was wrong was that at 24 mph (when the tranny should shift to third) it didn’t. The engine reved up as if the tranny was not there. This is an automatic by the way. I pulled over, discovered the disconected line, reconected it, put in new trans fluid and off I went. Still no 3rd gear. Took it to my mechanic friend, he said he dosen’t think it was loosing the fluid that did it, he said that would affect 1st and reverse not 3rd. So he flushed the trans, (there seemed to be alot of mosture inside) ajusted the linkage and replaced the modulator. Now he says he gets third gear most of the time, I have still to get third gear. He thinks that some crud got sucked up from the bottum of the pan and got stuck in some small passageway, and that with continued driving it will work its way out. Does anyone have any in-put on this? Was it the loss of fluid that caused this? Will I ever see 3rd again?


#2

I am assuming that you have the 3 speed TH350 transmission. If you were driving in high gear (3rd) when the engine reved up, you may have toasted the high clutch. Is there a good engagement of Reverse? Is there any sign of slipping in Reverse? If Reverse is okey, high clutch is probably okey.

Usually, loss of fluid does not contaminate the valve body. But, you might have the pan removed, check for debris, and change the filter. If you want to do some more diagnostics, connect a pressure gauge to line pressure and see what the line is doing at idle and stall and also, doing when the transmission is to go into 3rd. Also while the pan is off the valve body can be removed and the clutches and bands pressure checked for their state of health. With the valve body off the 2-3 spool valve can be checked for freedom of movement.

Let us know more details and how this situation is solved.


#3

No, you’ve burned up the direct clutch… Clutch friction plates in an automatic transmission are only thousandths of an inch thick each. They dont take too kindly to slipping. Its time to pull it apart. The good news is that 350’s are really cheap and easy to rebuild.

transman