Transmission Problems!

Reply Subscribe

Thread Tools

Search this Thread

Feb 23, 2004 | 08:58 AM

dadsgreenpsd

Thread Starter

Tuned

Joined: Oct 2003

Posts: 390

Likes: 0

From: Maine

Transmission Problems!

I have a 91 e350 service van, with a 3 speed auto tranny. This morning, it suddenly decided to stay in first gear. If I manually put it into second, it would shift violently into second and stay there. I can't get it to go into drive at all. 351 engine, if it makes any difference. 125k miles. Tranny has been slipping a little bit when cold, but this is a new occurence. Any ideas?

Feb 23, 2004 | 09:20 AM

94van

Posting Guru

Joined: Oct 2000

Posts: 1,577

Likes: 0

From: Southern MD

If you have the C-6 transmission, check the vacuum hose to the modulator. Other transmissions may be a cable adjustment.

Slipping when cold is usually a sign the seals are getting hard from age. When cold, the fluid bypasses the seals causing delays and slipping, then when it warms up, the seals soften and work pretty good. What does the fluid look like, red, or funky? Does it smell burned?

At that milage, if it hasn't been worked on, it may be due for some internal work.

Feb 23, 2004 | 05:13 PM

Yakk

Senior User

Joined: Jan 2004

Posts: 161

Likes: 1

From: The KeyStone State

About $15-20 may fix this.

Your transmission probably needs a Vaccuum modulator.
Replace your vaccuum lines while your at it.
The parts store will want to know what color stripe is on the modulator.

On the right rear of the tranny, there is a little metal can with a manifold vaccuum line going to it. That is your vaccuum modulator.
It is held down with one bolt and a clamp. Also check the vaccuum line at the modulator and the manifold for leaks. Check the metal tube for external rust-through.

The vaccuum modulator "tells" the tranny how much load is on the engine, so if there is no vaccuum present, it "thinks" the engine is under full throttle. That's also why you get the harsh shift.

Feb 23, 2004 | 08:11 PM

dadsgreenpsd

Thread Starter

Tuned

Joined: Oct 2003

Posts: 390

Likes: 0

From: Maine

Picked up a modulator tonight, will install it tomorrow. I completely forgot there were two choices, (purple or green). What would the difference be? shift points? I found that if I dared to, I could get it into third. I also found out it will do 65 in second ;-)