My 96 automatic SE overheats when I go up steep hills ( greater than 10%) at low speed ( under 30 mph). I can't get to my favorite skiing place anymore becaure invariably I get stuck behind a truck and there's no place to pull over and let it cool down. This is the only time I can get the problem to happen however.

I believe I've checked and fixed all the usual reasons for overheating, so this on stumps me. I've done the following:

1. Replaced the water pump and thermostat (3 years ago)
2. Replaced the radiator, lower, and upper hoses (10 months ago)
3. Replaced the fusible links in the compartment on the driver's left side under the hood that control the fans (4 months ago, because the low-speed one was burnt out)

For troubleshooting, I've:
a. Checked the hoses, radiator, and water pump drain plug for leaks - none found.
b. Monitored the coolant level. It hasn't changed since I replaced the radiator. The recovery tank is still full.
c. Checked that the fans come on when the engine is warm and idling.

Any ideas what might still be wrong?

 

Are you checking the actual coolant level in the radiator? The overflow tank level means nothing, really.

Have you tried bleeding the system? Any problems with the heat?

 

Check or replace the radiator cap. Pressure test and bleed it by running it up to temp with the radiator cap off.

Have the exhaust checked too, make sure the cat isn't clogged.
That could cause an overheating condition especially during longer periods of engine load. ie - climbing a large hill.

 

I would check your actually radiator level like stated above and then bleed the system. Also depending on how it overheated and if you didn't bleed the system then you might need to change your thermostat again.

 

I second, or third the above suggestions on checking actual fluid levels. My overflow tank was fine on fluid, but the actual radiator was down almost a full gallon and had air in the system. This caused the engine to overheat consistently. Easy fix though: Add fluid, bleed system as noted above.

 

If the Previous Owners (POs) did not change the coolant regularly you could have a radiator full of corrosion products, scale, and other junk. I had trouble with over heating in a 94 Mazda Protege after installing a donor radiator from a car with 181,000 miles on it. My mechanic pulled the radiator and sent it out to be steam cleaned and pressure tested. The radiator shop said it was the dirtiest radiator they had ever seen...about 1/3 full of junk at the bottom.

-Jim

 

OK. thanks for the advice so far. The radiator is only 6 mo old, so I'll assume it doesn't have junk in it. It may not have been bled right though.

I'm going to drain the coolant, replace the thermostat since it's so cheap, and run it up to temp with the cap off, and put on a new cap.

I'm going to try the hill again on 14 march, so I'll have to cross my fingers...