Car overheats idling in traffic

Question

I have a 2000 Chevrolet Impala. I recently had the water pump, timing belt, radiator, and thermostat replaced because I had a coolant leak/overheating problems. I now don't have a coolant leak, however, while idling in traffic, my engine's temperature starts to creep above 200 degrees F (the half way mark) and reaches 215-230 degrees F if I am idling for awhile (20min). I feel as if my engine shouldn't even creep past 200 after getting everything fixed. My car never went above 200 degree F before I had a leak.

Another thing to note, sometimes after having my heater on for awhile I smell a very faint hint of something similar to a candle after you blow it out. I also was driving my car today with the heat on and then turned the AC on after my engine warmed up and smelt a weird smell (not quite burning, but something I can't describe. It was not a good smell, something i would associate with heat though).

My question is;

What do you think needs fixing?

What should I have a mechanic check out next?

Thanks.

Answer 1

My top suspect would be a radiator fan that isn't running when it should.

The fans assist in transferring heat from the radiator to the surrounding air, and are most needed when the car is stationary.

This doesn't mean that the fan is bad. It could be that the relay is malfunctioning or there is a break in the wiring somewhere, so I would try to rule those out before making a call on the fan.

Answer 2

I had a similar problem with my 2000 Ford Focus last year. I can't remember what it was called, but basically it's a thermostat that's sits against your radiator that turns on the radiator fans when not enough air is flowing through the radiator. Like when sitting in traffic.

Look for wires running from the radiator to the fans.

They sit right between the radiator and exhaust header and what typically happens is that something causes you car to overheat and ruins these components. Mine failed right after I busted a hose and lost all my coolant.

Answer 3

I had a problem with my VW Golf overheating. I also changed various parts, the thermostat being the first as that controls the circulation of the coolant.

In the end I found the cause, the system wasn't pressurising as the o-ring on the filler cap had a kink in it and therefore wasn't making a good seal. I straightened it out and then it worked. Lesson of the story is check simple things first.

A new cap won't cost much, worth a go.

Answer 4

It sounds as though your radiator fan isn't kicking on. It may be as simple as whomever replaced your radiator forgot to plug it back in.

1. Check that your water pump is working correctly. Does your heater blow hot air when the engine heats up? If so you are circulating coolant, and the stuff you had replaced was successful.
2. After driving for a bit, once your temperature gauge is at least halfway, park the car but leave it running. Pop the hood and look at the fan behind the radiator, is it blowing? If not you can drive till the temperature gets closer to overheating and check again.

If the fan isn't blowing as I suspect:

1. Check the wiring for the fan as far as you are able, it should have a connector for removing the fan housing when replacing the radiator, see that it's plugged in.
2. If the connector is good and the wiring you can see isn't abraded, it may be your fuse. Look in your owners manual and find where the fuse/relay are for for the engine fan. Check them. Relays are more difficult to check, some auto parts stores will do the test for you though.
3. Unfortunately if all the above has failed it's likely wiring somewhere you can't see or your computer :( You can try to run diagnostics on that if you have a tool for it, but this is getting to the edge of what I'd recommend a non-mechanic try to fix.

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I don't like that you are smelling burning smells after replacing most of your cooling system. That usually indicates a cracked hose. Usually hoses crack on the inside, and should be replaced along with the cooling system components they connect to.

I'd inspect the hoses to and from your radiator, and to and from your heater. Do they look new-- as new as the work you had done? If not you may be able to take it back and request that the hoses are replaced tell them that you believe that one of the hoses are leaking. Show them the old hoses. Ensure that you tell them because this should have been done in the first place you'll only pay for parts, not labor.

Answer 5

I had a similar problem after changing a water pump, that I could not figure out. In the end I fixed it with a gallon of water. I refilled the radiator with straight antifreeze rather than a 50/50 mix, not knowing that glycol does not transfer heat as well as water. Using straight antifreeze caused the car to run hot and overheat at low speeds. Using the correct 50/50 mix solved the overheating issue.