240 1993 Stalled in traffic suspect overheating

240Dad · Post by **240Dad** » 11 Oct 2009, 17:23

It has been a while since I checked in. The last time was over a stalling issue and we determined it was the air conditioner compressor pulley stopping and causing the engine to stall. Replacing the compressor solved that problem. However, this weekend my daugther was in Pigeon Forge TN in bumper to bumper traffic and, after about 4 or 5 miles of it, it died. She made it to the side of the road by getting it started briefly and revving it enough to keep it running. I got there the next morning and it started and ran fine. I was in some stop and go traffic as I drove it home but it did not overheat. She did not look at the gauge when it stalled so I do not know if it overheated. I only suspect it. So, recently I had replaced the theromostat with a 190 degree, replaced all hoses and did a water flush and added all new 50/50 water antifreeze mix. The car runs great on the interstate at 70 mph and does fine in city traffic as long as it is not bumper to bumper stop and go. Any suggestions on how to approach this problem. I sure don't want to turn it back over to my daughter if there is a chance she will once again be like a possum in the headlights due to a stalled car in heavy traffic.

Additional thought after posting:
I changed the air filter a while back and noticed that the flap inside the air filter box had been duct taped closed so I opened it up. Could I be overheating the AMM (MAF)?

Post by **billofdurham** » 12 Oct 2009, 12:59

the flap inside the air filter box had been duct taped closed so I opened it up.

Do you mean that the only air entering the filter is coming from the manifold or is it coming from outside?

Bill.

240Dad · Post by **240Dad** » 12 Oct 2009, 13:18

Bill,
The current temp here is 62 deg. F. I just pulled the air filter out and looked at the flap. It is 1/4 inch open to outside air which means it is about 95% open to manifold air. What I don't know, and what I expect to be the next question, is whether that changes as the car is driven and heats up. I will have to drive it and see. Is that correct?

Update: I took the car out and got it warmed up. The flap remained at about 95% manifold air. I could not detect any movement of the flap. Can the theromstat that moves the flap be repaired or do I revert to opening it to outside air and reapplying the dict tape like the previous owner?
Thanks,
Bill

Post by **billofdurham** » 12 Oct 2009, 16:07

It does work on a thermostat inside the filter box and opens as the temp goes up.

They are noted for breaking down, usually in the closed position meaning that all air is coming over the manifold. Failing in the closed position, or even partially closed, could, in a worst case scenario, cause the engine to overheat but it will definitely play havoc with running and fuel consumption.

A quick test to see if it opens and closes as it should is to heat it up with a hair dryer. A longer test is to remove the unit, stick it in the fridge for an hour to see if it closes then heat it up with the hair dryer.

Many owners in hot climates fix the flap in the open position allowing normal temp air in all the time.

Bill.

240Dad · Post by **240Dad** » 12 Oct 2009, 16:48

Thanks Bill,
Two follow ups:
If I take the unit out and test it and it does not work, is there a way to free up the thermostat so that it will work?
Also, given the original problem of the engine stalling in stop and go traffic then running fine after it cooled down, is this the likely problem?

Post by **billofdurham** » 13 Oct 2009, 12:31

If it is faulty the easiest solution is a new thermostat, available from IPD at $7.98. Also read the write up on IPD's site here.

As yours was only partially open at an ambient temp of 62F it is the most likely culprit. Some owners would disagree about my "easiest solution" and would advise blocking it open or even taking it out altogether. However, if the car should go to colder climes that would have a detrimental effect on the running of the car.

Bill.