91 Transmission help

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Jun 17, 2004
Cruiser did something odd the other day. We were on the coast, stopped at the aquarium for a few hours and when we went to leave, it would not shift out of first gear. The parking lot is pretty far from the highway, and I was trying to manually shift it. If I put it in first or second, it would shift between those gears fine. As soon as I put it in 3rd or fourth, it locks down into the first gear. :confused:

It seemed as soon as the trans temp warmed though, I was able to put it in 3rd or 4th and it would shift on it's own again. Drove home fine, about 70 miles or so.

Parked it, and wanted to check it out after my work week was over. I took it to the store yesterday after work, and same thing. However, the trans didn't get to temp since the store is only 7 blocks or so away. It shifted fine for a bit, then all the sudden would just slip horribly like it was in neutral so I manually downshifted into second, locked right in and I was off again.

Now, I haven't checked anything yet like the fluid level. I plan to do that today...

Any ideas? I believe it has never been rebuilt according to the PO. The truck has 230k on it and the last 30-40k it has been WAY under geared with 4.10's and 37's on it. I'm sure the transmission is close to death, however it has shifted perfectly fine and NEVER slipped on me since we bought the truck. The gears are going in this week (5.29's) so I'm hoping to give the transmission a break and planned to service it as well.

If I do end up having to rebuild it, how much am I looking at it costing? Having never torn into an auto...are there special tools I would need or is worth it just to pay a pro? Are these transmissions easy to find? Thanks for the help in advance!:cheers:
I would check the fluid level and quiality of the fluid first .. then a good fluid flush .. there is any code throught the OD light .?

Add in your list an stall test ..
Check fluid,pull pan ,clean filter,flush and fill.asap.@ cents Mike
Check the transmission cable that goes to the throtle body. Set it to factory specs. I think you should only see 0.5 mm of the small indicator attached to the cable. This fixed a similar, although not the exact same issue with my '92.
Will do all, thanks for the advice. Not sure what a stall test is...:confused:

I'll check the fluid (I'm sure it could use a good flush anyway), clean the filter and top it off with new stuff.

I'll check the cable as well, I remember reading something about that being out of wack and causing some issues. Thanks for the tip.

I'll report back.

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