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Random overheating in stop and go traffic

I drive a 2004 Honda Civic. About a month ago, my car started to overheat. The next day, I took it into the shop,and they said the thermostat was sticking,and I had a small leak in the radiator. I got a new thermostat, radiator (they did not have anyone to repair), and flushed the system.

A few days later, the car started to overheat again, and quickly went down. We thought it was a fluke. A few days later, it did the same thing and we took it back to the shop. They said nothing was wrong and let the car run with the radiator cap off for a while in case there was a bubble. Since then, it has has started to overheat a few more times. So the, problem is not all the time, just every so often. Several parts have already been replaced, as noted.

What we have found in common is that each time it starts to overheat, we are in stop and go traffic. It has always been hot outside too (but it is summer). When we begin to move at a regular pace, the car temp goes down. I live in a city, so it is impossible not to get in stop and go traffic on a regular basis. Not everytime we are in stop and go traffic it does this, but since the repairs, it has never overheated while moving at a reular pace. Any ideas what is going on here? I have $500 of repairs put into this problem and am afraid there was a different problem to begin.

Any idea what the problem is?

The problem might be with the electric radiator cooling fan or one of it’s controls. Open the hood, start the engine and let idle while watching the temperature gauge. As the temperature rises at some point the electric radiator fan should turn on. If the temperature gauge starts to go into the red zone without the fan turning on, there’s a problem with the radiator fan circuit.


What we have found in common is that each time it starts to overheat, we are in stop and go traffic.

If it ONLY occurs when you are in traffic, there’s a good chance that the electric cooling fan may be your problem. The next time this occurs, find a safe place to get off the road and open the hood. If the fan is not spinning, you’ve found your problem. Then have your mechanic find out if it’s the fan itself, or something in the electrical system, which is the root cause.

Are you running AC when it overheats?

Yes, we are running the AC when it overheats. Some times it runs with no problem, and then other times it heats up. It only seems to have trouble when in traffic, when we pick up speed, even with the AC, the temp goes down.

I would take a garden hose and wash off the front of the a/c condencder and check to make sure the rad. fan(s) or working like they should be . have you replaced the water pump? just thinking out load.

You may have a radiator fan motor that is failing intermittently. You can check the fans just by turning on the AC, both fans should start immediately, even if the engine is cold. If they work when cold, then when the car overheats, if you can find a safe place to check them again, pull over and do it.

One more thing, the part about the bubble. That makes me think you mechanic is not aware of the bleed valve located in the thermostat housing. That is how you get the “bubble” out, not by removing the radiator cap. If removing the radiator cap would work, your coolant recovery system would have gotten the bubble out on the first day.

My daughter had this same problem yesterday. When she got home, I checked the electric fan, and it was running. I then looked in the coolant reservoir, and it was dry. I filled it to the brim, and we ran the car for a minute or two. The water was not sucked in. We shut it down and let it sit overnight. Mrs JT drove it on an errand to her favorite boutique store (pronounce it: Tarjay), and there was no overheating. When I got home, I looked in the reservoir again, and all but a couple fingers of water was sucked into the radiator. I told a friend at work this story, and it reminded him that he has 2 gallons of Dexcool in the shed and no GM vehicle in the driveway. He’s bringing it in on Monday for me - a freebie. Score!

i have a 2001 honda civic dx 1.7 l same problem im beginning to think it is a failing cat converter

I’m beginning to think it’s a head gasket with a pinhole leak.

@jtsanders if you continue to lose fluid, either you have a leak or head gasket leak.

It would be great to know the outcome of this problem you had and what was causing it. It helps future users.

If you want to know the outcome, click on OP’s avatar

Then you’ll have the opportunity to send him a personal message

Anything less is probably a waste of time

I’ll bet lunch he hasn’t been back on this website in several years

Thanks for the heads up DB

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