Plymouth Acclaim

1993 Plymouth Acclaim Engine Malfunction When driving Always

I have a 1993 Plymouth Accliam 2.5L. This car has run wonderfully until a few months ago it began to overheat. I had the car taken to my dealer and they told me the head gasket was leaking, a common problem with this model engine. they replaced the head gasket, allong with the PCV valve and hose, the radiator cap, cam seals, and cam plugs.

The car runs well, but I noticed the temperature guage fluctuates while driving, it will move close to hot, then down close to cold. I asked my dealer about this and he said it was normal and gave me a service bulletin to read. It states: Some temperature guage reading fluctuation on vehicles equipped with 2.2L or 2.5L engines during cold weather is NORMAL. This fluctuation does not indicate a cooling system problem, engine problem, or a malfunction of the temperature guage.

The temperature guage will rise until the thermostat opening temperature is met. When the thermostat opens, the guage will drop to the lower portion of the normal operating range. This occurs because the thermostat has allowed the cold coolant from the radiator to enter the engine. The cold coolant is sensed by the temperature sending unit resulting in a lower temperature guage reading.

This cycling or fluctuation of the temerature gague indication will be observed until the entire cooling system becomes normalized (obtains the same relative temperature). The colder the ambient temperature, the longer this condition will be exhibited. In extremely cold ambient temeratures the fluctuation may continue indefinitely.

When I noticed the guage fluctuating, it was 60F and sunny out, I was driving in light traffic. I just wonder if my car will be as dependible as it previously was during our summer months when its 110F, I have the A/C on and I'm in bumper to bumper traffic, something common here in Phoenix.

My question is why does this happen? Previously, when the engine would reach normal operating temperature , the needle would move into the lower end of the guage and never move. I would think if the dealer replaced the parts with all the indentical ones, this shouldn't happen. Could it be the thermostats fault? I previously replaced it with one by Stant. Although its supposed to be the correct one for my engine, I noticed in the Haynes manual, the illustration on the factory thermostat has a smal air vent valve built onto the top of it, while the Stant one does not. Is there anything I can do to fix this, or should I just ride out the warrenty (12 months, 12,000 miles) and see what happens?

Thanks much!
A frustrated Acclaim owner

Actually, the thermostat that I would be using is the one that has the small vent hole. My understanding is that the thermostat will allow some coolant flow to travel through the system. This will alleviate some of the pressure in the system and equalize pressures in the system as well (This will also help in relieving pressure on the head gasket). I have a '88 Sunbird that had the same problem. In cold weather, the temperature gauge would go from one extreme to the other. Since the last head gasket (common on these cars as well) I have drilled the relief hole on the thermostats myself. Since then I have not had any trouble. You may want to make sure the system has been properly purged of all air.

1989 Plymouth Acclaim Fuel System   

After replacing plugs, plug wires, distributor cap, O2 sensor, and catalytic converter my 1989 Plymouth Acclaim still has problems, especially at very low speed after the engine has warmed up. It runs okay while accelerating but will often die if you give it just a little gas and then let off the pedal. Lately it has died at highway speed as well, and is becoming harder to restart. Any ideas?

Check for vacuum leaks and check EGR valve