My auto trans won't go into gear

HOOSURDAD

MEMBER
1978 FORD F-250
150,000 MILES

My trans was slipping, so I added some fluid. The wrong kind I guess, because I had to get towed home. I dropped the pan and added 9 quarts of type F atf, and also changed the filter. The truck was shifting perfectly for a day. I decided to add 1 more quart of atf. Trans. Would not engage again, So I dropped the pan again, put the still new atf back in, and now the trans. Still doesn't engage. Someone told me I have to drop and drain 3 or 4 more times to free-up the modulator. Is this true?

3 Replies

HMAC300

MECHANIC
48,601 POSTS

It's probably time for a rebuild. When you dropped it the first time was there junk in the pan. If just a small amount of shiny stuff that's ok but if big pieces it's probably a clutch gone out.
You really need to check the pressure, if it's low like less than 50 psi then something is stuck.

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Saturday, October 15th, 2011 AT 6:21 PM

HOOSURDAD

MEMBER
2 POSTS

Hi, there were only tiny pieces in the pan. Does that mean my clutch is still ok?

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Saturday, October 15th, 2011 AT 6:28 PM

HMAC300

MECHANIC
48,601 POSTS

It's hard to say the truck is 32 years old. The trouble when a trans goes it's either clutchs or seal in thepistons that apply the motion. That truck should taek type "F" fluid as it's a slicker type of fluid. If the pan is big it's a C-6 if the pan is small it's a C-4 those were pretty touble free until they failed or started. You could have a valve hung up but I kind of doubt it. But that would require dropping the valve body and taking it apart and cleaning it. That is not for beginners or diy's to do. It's really better to have apro trans guy look at it and let him give an opinion instead of wasting time and money trying to fix it. Even oil is exspensive now

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Saturday, October 15th, 2011 AT 6:33 PM