EDIT: If this is in the wrong forum, I apologize, I didn't see a transmission/drivetrain section.

1991 S10 Tahoe. 96K Miles. 4.3. 4x4. Automatic

I just picked up this truck, and one of the problems, I was told is a possible bad vacuum line on the transmission. The previous owner told me it has this problem while cold, and usually corrects itself once the transmission warms up.

1st and 2nd gears work fine.

When driving the truck in OD, 1st gear is perfect, it shifts to 2nd perfect, and 2nd gear is great. Reverse also works flawless in the truck.

When it's time to shift into 3rd, the transmission doesn't want to shift, it revs as if its in neutral.

I was told by the previous owner that he spoke to a transmission specialist, and was told since the truck has 1st, 2nd, and reverse, that it isn't the bands? (I don't knowa lotabout transmissions yet)

I was also thinking, could it be a valve in the valve body for the 2nd to 3rd upshift?

Any ideas guys?

Thanks in advance,

-Brandon

 

If your trans has OD then there is no vacuum line, you have a detent, or TV cable. since the other gears work I would have to say that the TV is ok. sounds to me like you either have an internalpiston leak or you could have a problem with a clutch pack/ band. But either way, sounds like you are in need of a rebuild. You could however if the current fluid looks okay, try to change the fluid/filter and put a bottle of Lucas Oil Stabilizer for automatics in there. Good luck, Korey

 

Thanks for the reply.

To add some missing information that may help diagnose this problem further:

It's a 4 speed automatic with overdrive.

I was told there's a small transmission leak, but the previous owner was unsure of where it was coming from. He said he had to add about a 1/2 quart every 3 weeks or so.

I definitely agree that it's time for a rebuild, I'm actually planning on having the engine and transmission rebuilt soon, but figured I'd ask for help diagnosing the problem, and if it was an easy fix, I'd take care of it myself until the rebuild.

Thanks again Kordog,

-Brandon

EDIT: Just out of curiousity, what kind of price range would I be looking at for a rebuild? I know the cost would probably vary depending on what needs replacement, where I take the truck, etc... I was just looking to get an idea of the cost. I've never had a transmission rebuilt before. I'm seeing "new" rebuilt transmissions going for about $1000 online, so I was wondering how a rebuild compares to buying a "new" unit.

 

well i am having the same problem, i have an Acura integra LS 1994 it was running perfrectly for about 3 months than as usuall i parked my car the next morning i started my car it was running good for about 7 minutes than it goes to Nutural i restarted the car it goes but than again goes to Nutural i am not a mechanic but from personal oppinion it seems like something is blocking the flow of the fluid inside the transmission but i have a plan of changing the filter but i don't know where is the filter located but i will take it to mechanic with a hope that they don't charge more than it should be.

 

actually i am not sure what you mean by that but i have it Automactic