87 Buick Century Stalls When Slowing Down

PepBoys put in a belt tensioner. This seems to make sense but after one hour on the highway, when slowing for toll or exit, the car stalls out bigtime.

Despite it age, this car has only 30,000 miles. Car was owned by my mother-in-law who never made left turns.

Car has new oil. Trans fluid seems to be ok. Passed PepBoys diagnostic.

It’s possible that the lock-up torque convertor isn’t dis-engaging after driving at highway speeds.

Is this what happens when it stalls? Driving at highway speeds and then you exit, you stop at the end of the exit and the cars stalls, the car might restart but stalls right away, after a number of attempts it finally restarts and stays running and you can drive off.

If this is what is happening it indicates the lock-up convertor is not dis-engaging. It’s a common problem with this year,make and model.

Yes, this is what happens. This looks like the answer. I appreciate it very much indeed.

When The car is slowing to the stop, is the engine erratic? Is the car jerking? When the lockup torque converter doesn’t release, it’s like the transmission is stuck in high gear. If you have ever driven a manual shift transmission, and you didn’t depress the clutch, that’s the “cogging” of the engine which results.
Is there any problem with idle at any other time? If there were, that could be a problem with the idle air control valve (iac).

Yes the car is jerking. Otherwise idle seems to be ok. I guess the IAC is ok. I will try to relay this followup to the mechanic.

Thanks very much for the follow-up.

If the the car is jerking like it is a manual transmission car when you forget to release the clutch, you have the classic case of the torque converter clutch stuck on. It usually is the TCC solenoid but it also can be the shuttle valve that directs the oil flow to push the torque converter clutch disk into engagement.

One diagnostic test is to switch to neutral when coming to a stop after a long highway cruise and see if the engine idles okey. Then, if the engine dies when you switch to OD or Drive you have the diagnosis.

The replacement of the solenoid does not require removal of the transmission but the side cover has to come off to gain access.

At the risk of stating the obvious… PepBoys told me this morning that the flywheel would have to be removed and then drop the transmission to replace the lock-up torque converter (a difficult part to find). This is really a 94 Buick Century. I have concluded that it does not pay to do all of this work in such an old car.

I will relay this new info to the mechanic. It would be great if I could keep the car and not have to junk it.

WHOA!!! WHOA!! Hold on there!

The problem is most likely in the valve body NOT the torque convertor itself. There is a shift valve that sticks. You need to see a transmission shop. The flywheel doesn’t need to be removed, there is a side cover on the transmission that can be removed to fix the problem

Maybe TRANSMAN can shed some light on this problem.