Transmission not shifting, what to check????

[Eric Wettschreck]

89 chev pickup, 1/2 ton, 4wd, 350, auto trans- 3 speed w/overdrive.

Transmission was working well. Saturday coming home I had to bust through a couple drifts. Pulled into garage, turned on the heat to get rid of the snow. The next day, start truck, let warm up forever, put it into reverse to back out...no problem. Get onto the road, put in drive, no problem. The problem is it will not shift out of first gear. I have reverse just fine, and first gear, nothing else. The shifter linkage moves it's full travel, I checked it on the column and on the trans. This is the only linkage leading to this trans. I can't find any broken or disconnected wiring harnesses. Pulled the dipstick, fluid is pink and does not smell burnt.

I'm not a transmission expert.

What makes this thing shift? Does this have shift solenoids in it???

A fella I work with told me to check the vacuum module. I can't find ANY vacuum lines going to this trans. There is a vacuum line going to an electronic thingy then to the EGR diaphram. There is another vacuum line, coming from the same place near the intake leading to what looks like a MAP sensor. There is another vacuum line leading to the emissions thingy canister near the radiator, that's it for vacuum lines.

I replaced the fluid and filter this summer.

What does a guy check next????

[Macgyver55]

Sounds like maybe the throttle valve or cable may be sticking. This is what holds the trans in gear longer while accellerating hard. If it sticks, the trans thinks you have the throttle to the floor and it wont upshift until you wind it out all the way. First check the cable at the throttle body (the one that goes to the trans) for slack. Or, if you can find a dry stretch of road, wind it out to see if it shifts then. If there is slack, or if it shifts after winding it out then the valve or cable is sticking. Post back results.....

[Eric Wettschreck]

HWY 59 is good and dry. I took it out and wound the ever lovin you know what out of it, for a lot longer than I felt comfortable at that high RPM's.

No shift. Stayed in first.

I still have reverse, and first gear, and that's all it has.

[Macgyver55]

Was there slack on the downshift cable (lower one) at the throttle body? Sometimes tugging on this and letting it snap back will free up a stuck valve. If its not that, the next best thing would be the governor assembly. After that, it gets messy ....

[Eric Wettschreck]

From what you've told me, and a few other guys.............................I'm thinkin it's gettin messy.

I'll be shoppin around for a trans in the next few days, or a different truck.

FOR SALE: good running 89 chev 1/2 ton pickup, needs a tranny.

[jeffreyd]

200 bucks you deliver to phoenix??

[The_Diesel]

I got a '00 Chevy that is doing the same thing, except it's 3rd gear for me. It will go into it, but I have to rev it real high and kind of let off the gas and baby it into gear. No overdrive at all. Taking it in tomorrow to the tranny shop, see what she'll cost. I'm not too happy about it. Coincidentally, I, too, was in some deeper snow when it happened. As soon as I hopped on the interstate after the snow banks I noticed it.

[Eric Wettschreck]

200 bucks you deliver to phoenix??

For 2 hundo and a box of PBR I'll blow the snow from around it when you come pick it up.

[Eric Wettschreck]

Yesterday while I was at work a friend of mine who is a trans guru came to my place, put the truck in the garage (yeah, I left the keys in it) and checked things out.

He said it's pretty much smoked. Get a different one or pull it and have it rebuilt.

He also told me these 700r4 transmissions are a bit famous for roaching the higher gears while busting through snow drifts. According to him, these are one of Chevy's better transmissions and this is their Achilles heel. Kind of a bummer, this has been a real good running pickup for me.

Macgyver, thanks for the help. I really do appreciate the insight you give me (often) when I have car problems.

[The_Diesel]

Yep... took mine in and found out third gear was roasted. Going to be about 3 grand after they totally rebuild it, and fix/update a few other common problems on these transmissions. It sucks, but once that's done the guy told me it would be a better transmission than when it came from the factory, so it's a lot cheaper than ditching it and making monthly payments on a new one

[deadeye]

It sounds to me like there is something going on with the vacuum modulator. Either the line got totally ripped off/out or the modulator itself got pulled off the transmission.

[The_Diesel]

Not sure about the 89 model, but my '00 doesn't have the vacuum lines. Don't mean to insult you Deadeye, as I had multiple people tell me that same thing, and I mentioned it to the mechanic and they quickly corrected me too.

[Eric Wettschreck]

No vacuum modulator on my 89 either.

I'm doing some shopping around for a used or reman tranny. Finding them between 350 to 1500 depending on what a guy wants to do.

[mechanico]

It sure sounds like something got yanked off...not necessairly from the tranny itself. The vacuume idea sounded like a good place to start. If you can find the park safety switch, check that and follow the wires as afar as you can. I don't know specifically about that year chevy, but some have an electrical harness hooked close or on to the gear selector cable at the tranny end. If that got turned out of sink, that could do it. And check the bushings in your shifter linkage. Also, check your cooling lines that go to the radiator. If you see pink stuff in the snow you broke one. I'd check ALL the ancillary stuff before I took it to a tranny shop. Sometimes people take advantage of our ignorance. Good luck!