Overheating 93 Acura Integra LS

A&Q about 350Z

The facts: 93 Acura Integra LS, 1.8L engine, 234,000 miles.

The situation: this morning, I noticed that as my car idled, the temperature went up to nearly the top (extreme right, to be fully accurate) and was proceeding to overheat. However, as I drove, the temperature went down to its normal spot.

I got to the gas station, as I stopped, it proceeded to heat up. I popped the hood, popped the cap, filled up the radiator as best I could (though it was boiling over at the time) and filled the well. As I drove off, it was fine, but as soon as I got into traffic and slowed up, the needle went up again.

Question: why would the temperature go up as you idle? Any ideas about the problem?

Sorry if this is an elemental problem, but I'm trying to figure out what the issue is....

I have a few guesses. First, try the obvious stuff like making sure the thermostat fully opens when hot. Thats a job for when its out of the car and you can test it in a pan of boiling water... but at that point, you might as well just get a new one for $15 and just put it in.

The other possibility is that the electric fan is not coming on. Could be a bad fan motor, a blow fuse, bad relay or circuit breaker; all of which can be tested, either by you or a shop.

It could be a buildup of flake and crust in the radiator or corrosion in the water jacket of the engine, but those are typically very gradual problems. Its not likely they would just crop up. Even so, a crusty radiator can be flushed for under $50 if you remove it.

Another distant possibilty is that you water pump is dying. Its rare, but the bearings can start going and drag down the pulley. Usually the belts squeal as an indicator of that but not always. The impeller blades could be toast especially if its the original water pump. Little flakes of rust and junk can sandblast blades, not to mention they can corrode themselves.

The good news is that the worst case scenario is that you need a water pump or a fan and those are not dreadfully expensive things. Not cheap, but not wallet breakers.

> Point 1: bad thermostat...I'm going to get a new one right now and try to put it in.

> Point 2: bad fan/fuse/etc...Hmmm...okay, let me give a little more information. When I first start the car and it gets to the point where the needle moves to near (but not into) the red, I check and the fan isn't on. It moves freely if I push it, but it's not moving on its own. When I shut the car down after driving home for an hour and a quarter, it goes into that post shut down thing where the fan is spinning and the engine is cooling.

I'll check the fuse like you say, but my guess is that it should be okay because it runs at the end and that should be the same circuit served by the same fuse, right?

> Point 3: Crusty radiator...could be, but I doubt it...the water is a nice green color and when I pumped that thing out 16k miles ago, it looked beautiful then, no junk in it...However, I'll keep this in the back of my mind in case the new therm doesn't work.

> Point 4: Bad water pump...The water pump is pretty new. I changed that out 16k miles ago when I re-did the timing belt (see point 3).

Thanks for the ideas you gave me. I really appreciate it! Do you have any others?

Great. That's the easiest and most likely culprit. Not to mention the cheapest part.

Same fuse, different circuit. The fan should be running if the engine is that hot when you're idling. The fact that it runs after you shut down is a separate relay/circuit. The good news is that we know the fan motor is not to blame since it does run. It also means the fuse should be fine, but it leads me to believe that it might be the relay, the sensor (which is usually two-stage; one stage for a hot signal while the engine is running and another for if it gets really hot after its shut off.... your parts counter guy will know that) A diagnostics of the sensor and relay might be in order if the new thermostat doesn't work.

good idea and wise deduction. They usually crust up slowly.

Even new water pumps could be bad, but you're right.. at this point its the last thing to check.

Have you considered an exorcism?


Honda motors are known for overheating when air is trapped in the sysem, you should also bleed it when you put that new thermostat in.

True, but isn't the surge tank the highest point on them? If so the air should go in but not come out... unless the surge tank is low.

The tanks are low, they have bleeder valves on the top water neck. This problem usually doesnt just come into play when its idleing- but non the less its something that could come into play.
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