I just got a 93 Jimmy, RWD, 253k miles. Guy told me the previous owner was complaining about the transmission not operating after a long drive. He replaced the filter and fluid and didn't have any issues. I took it on the highway today, testing it out. In overdrive, i pressed the pedal to the floor and heard a loud pop and the engine sounded like it was in neutral. I let off and accelerate normally and it moves down the road. When I come to a stop or slow down to where I think I should be in a lower gear the transmission acts like it's in neutral again. This happens in overdrive and drive. I can start off in 1st and shift through the gears all the way into overdrive. If I accelerate hard in overdrive though it won't down shift just start revving like it's in neutral. What could the pop have been? I don't think it's a clutch pack issue because i can move in all the gears once I'm in the proper gear range.

 

Sounds like you snapped something driving a lower gear, likely the sprag. When you step on it, the trans downshifts to a lower gear, that gear is burnt up or broken, you get neutral. When you slow down, it also downshifts, again no pull when it reaches the bad gear.

In OD and D, the computer has full control of the shifts. In manual 1 and 2, the gear shifter changes the internal flow of power to give you engine braking, bypassing the bad element inside the trans and it pulls again. You get it going fast enough to hit 3rd gear and overdrive and upshift manually into D or OD then the trans goes back to computer control.

 

Thank you for the explanation. It was suggested that I try changing the fluid and filter again, since that solved the problem a few months ago. I knew something was bad when there was a layer of sediment in the pan. I'll just have to wait and have it rebuilt.

On a side note. I need it to get around in. Would it be awful of me to drive it around manually shifting it? Nothing long distance. Just a few miles around town.

 

Where exactly did you hear the pop sound coming from?Did it sound like a motor back fire?where you able to feel the pop when it popped?From what your telling us,is that the tranny has over 253K miles on her.If you plan on keeping your ride for a good while..It`s just better to replace the tranny with either a new one or rebuilt one.If you plan on selling it?You can just find one at your local pull apart, or another local vehicle grave yard for a price around of $500.00.With any vehicle that has over 253K miles on it, it`s gonna have wear and tear on both engine/tranny.Once the tranny starts acting up(with that many miles) it`s just best to replace it.Defintely sounds like an internal problem for sure.

 

If you can shift the tranny manually, you should be good to just drive it around town.But don`t chance it drivng the freeway.

 

If it is damaged, driving it will not increase the cost of a rebuild much if anything else goes as a result. But it could quit moving at any time, or debris could cause new issues.

A F&F is a waste of money, sounds like the "fixing" of it originally was the sediment was plugging the filter. Drive a while, the sediment gets sucked against the filter media, plugging it. Let it sit a while, the debris falls off the filter media, restoring flow. Remove the sediment with a F&F, works fine until a new layer builds up.

I would recommend a rebuild over used, most transmissions that will fit are just as high mileage, it is rare to get even a new trans to go over 150K without a rebuild. We start seeing just about all transmissions fail around 125K or so, many start having wear issues that can be fixed with a new solenoid or valve repair around 80K. A rebuild typically has a 1-3 year warranty, the junkyard gives you 30-90 days and the labor to install it is not covered. If the used unit doesn't work or fails soon after install, by the time you get a working unit going you are fast approaching a rebuild price anyway. Shop around, we get about $1100-1300 for that job, but larger markets like Indianapolis can get up to $2K!