Questions and Answers

Chevy Asuna Sunfire Cooling System Q. My wife has a 1992 Chevy Asuna Sunfire. Over the last three years I have had a problem with it running hot in the summer. I have checked all the hoses, cleaned and flushed the cooling system, replaced the Antifreeze, 60/40 solution. It gets below -40° here in the winter. Checked and changed the thermostat, taken a compressor to clean the radiator fins and checked the pressure in the cooling system.

What I can not understand is why does it run cold in the winter and hot in the summer? Do you think I should run a 50/ 50 mixture of anti freeze in the summer? Or what other suggestions do you have? She told me that this problem started when she took her car in for service at some dealership in Calgary.

In the winter I also have to place a bib over the radiator to allow the heater to warm the interior of her car, but it still runs cool. I have had to put a bib on it ever since it was new.

Thanks for your help,
George
Galata, Montana

A. I haven't seen a Chevy Asuna in quite a while. I they came out, or more precisely, brought over in 1991. They were made by Isuzu and were the Isuzu Impulse Coupe labeled and sold as the Asuna by the Chevrolet division of General Motors.

They didn't bring a lot of them into the country and, I think, they stopped importing them in 1996. They were a peppy little car but I didn't care for them because they didn't come in my size, a 48 long. They also brought an SUV called the Sunrunner which looked an awful lot like an Isuzu Amigo.

Anyway, I think your problem is still with the thermostat. I would try another thermostat before doing anything else. When you install the thermostat make sure the jiggle valve is positioned at 12 o'clock. If not it will overheat. Also make sure you are using a 50/50 mix of antifreeze since it is also offers boil over protection.

As for running cold in the winter, it is not unusual for vehicles in extremely cold climates to need a radiator cover to get sufficient heat in the winter. I know, personally, here in Minnesota that I have to completely cover my radiator to get heat into the passenger compartment.

Another thing to look out for is the type of antifreeze you use. There was a TSB issued about approved antifreeze types.

Bulletin Number: SB94-14-005
Issue Date: December 1994
Group: Miscellaneous

Propylene Glycol-Based Engine Coolant Warning

Affected Vehicles:
All Isuzu Passenger and Light Duty Models.

Service Information:
Some new propylene glycol-based engine coolants, such as Safe Brands' Sierra engine coolant, have recently been marketed in the automotive service industry as "environmentally safe" alternatives to conventional ethylene glycol-based engine coolants.

Isuzu does not approve propylene glycol-based engine coolants for use in Isuzu vehicles.

Propylene glycol-based engine coolants do not meet Isuzu engine coolant specifications. Use of propylene glycol-based engine coolants in Isuzu vehicles can cause the following:

• Reduced heater and defroster performance.
• Decreased boil protection and freeze protection.
• Decreased cylinder head heat transfer.
• Corrosion damage to cooling system metals, if mixed with ethylene glycol-based engine coolant.