CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

98 Honda Civic Overheating, Mechanics have given me 3 different reasons?!?!

I have had my 1998 Honda Civic for about 5 years now… I bought it used. Occasionally I have noticed my oil levels have been low every 2 months or so. Oil is not being burned and doesn’t leak. It hasn’t affected performance from what I can tell. I have basically monitored the levels and everything has been fine. There was also an electrical issue since I have had it.

About 8 or 9 months ago, I noticed the temperature gauge was basically in the red while driving. I pulled over and noticed the oil was reading empty. I put oil in it and took it to the shop the next day. They told me the head gasket was bad and that the oil and coolant were mixing and recommended I replace the engine. I asked them how long I could manage before the car quit entirely and he said maybe a month, two if I kept doing oil changes.

I put the heat on while driving it, and the temp was normal. I took it to another shop the same week. They couldn’t get it to overheat for a couple hours. The guy told me it was probably the fan but wouldn’t know unless he could see it overheat. He said the fan would cause it to overheat at stoplights when there wasn’t air on the engine. When the car gets hot, it doesn’t get worse at stoplights and is only after I’ve been driving like 20 minutes that it heats up. I asked that he call me as soon as he knew what it was and I would decide whether I wanted it fixed that day or not. Then I didn’t get a call for awhile, and when I called them, they said the guy was out getting the part. I felt like they were rushing so I would replace the fan. I asked if it was the head gasket because I didn’t want to fix a fan if the engine needed to be replaced. They said it was not. I didn’t replace the fan. They also told my husband that we could save wear and tear on the engine by putting the air conditioning on instead of the heater. When we do this, it overheats. Its only when the heater is on that the temp stays normal.

I have been driving the car for 8 or 9 months now with the heater on with no performance issues. It doesn’t overheat and even when I forget to put the heat on it goes up to the red, but doesn’t “overheat” with the steam and whatnot. It doesn’t seem to do anything to affect the performance of the car. We have replaced the radiator cap, which had pieces falling off, and it didn’t help. The check engine light came on yesterday and the code indicated something to do with the transmission.

We took it to a third mechanic today and he said I needed a new thermostat… I’m so frustrated…

I do not see any sort of film in the oil. We just flushed the coolant today and there was no sign of oil. I’m totally lost on what to do. I feel like the mechanics have lied to me about what was going on. They contradict each other and the little things they told me don’t seem to be the case or don’t work.

Any advice?

I like your third mechanic. The heater is like a mini radiator and it bypasses the thermostat. Something is keeping the coolant from circulating through the main radiator and the thermostat is the most likely suspect, but it could be a hose that has delaminated on the inside and is blocking the flow to the radiator.

BTW, oil does not just disappear. You are either burning it or it is leaking, one or the other. Oil will usually burn faster if the engine is overheating.

Too many possibilities. First addressing the temp issue a bad cooling fan for the radiator seems a simple culprit, except for when you run out of oil. Find a good independent mechanic to assess the fans and oil loss.

My guess a bad cooling fan and clogged pcv valve.

If the radiator fan doesn’t come on after idling the car for 15 minutes – and the dashboard temp guage says the engine in overheating, that could be due to either a bad fan or a bad coolant temp switch. Usually it is the latter & is inexpensive to fix. It is easy for a mechanic to test.

Overheating can severely damage the engine. Even a single episode of overheating. You’d be money ahead to immediately stop the car and turn off the engine when it overheats. If it starts to move into the red zone again,the first thing to do is to be sure to turn the heater to full on and turn the heater fan to full on. This will dissipate some heat from the engine through the indoor heater core.

If the overheating is occuring while driving 40 mph or more down the road, that usually isn’t the radiator fan. The radiator fan normally doesn’t come on in that circumstance. That’s a problem with the ignition timing or the radiator or the radiator cap or the thermostat or – if this is the case, get your wallet out – the head gasket.

You are probably burning oil at an acceptable rate, (most cars use some oil) but letting it get low by not checking often creates the problem you described. That’s because when your oil level gets low, it burns faster. If you checked it more often, every two weeks or even every week, you’d never have the shock of finding no oil on your dipstick.

Buy a few quarts of oil and get in the habit of checking the dipstick at home when the engine is cold, and you are not rushing to get somewhere. Checking at a gas station is a pain if you get your hands or clothes dirty, or there’s a line of cars waiting to get to the pumps.

I agree that the thermostat is a plausible explanation for your symptoms, you should replace that regardless. It happens to be an inexpensive part and on some cars, an easy repair - maybe a DIY. If you have not changed the thermostat in the time that you’ve owned the car, you don’t know its age, so it could be the original one and due for replacement. Start there and see if that changes the “overheating” symptoms.

The lack of oil in your coolant is a good sign, you may have dodged a bullet. I hope so!

I always change out the thermostat and radiator cap every time I flush and fill the coolant. It’s cheap insurance. And, may have solved your problem in one step. The radiator cap and thermostat are just as important to a properly working cooling system as the radiator and hoses. If one of these fails, you could be facing overheat problems. And changing them out is typically easy to do.

You need to stop going to mechanics who speculate about the cause of the overheating, and find a mechanic who knows what he is doing. The first thing a mechanic should do is pressure test the cooling system. If your engine passes the pressure test, next you should get the radiator flow tested.

Sometimes, a radiator on an old car can get plugged up, not so much that the coolant won’t flow through it, but it can get mineral build-up in the small passages where the coolant gets cooled down. Flow testing the radiator might expose this problem, but this might be a case where you let a mechanic put a new radiator in there just to find out. Diagnosing a partially clogged radiator can be difficult, but if your fan works, and your thermostat is functioning properly, and there are no leaks, the radiator is the next logical step.

Think about it for a minute. There is a pretty good chance you are driving around with a 14-year-old radiator. If you are, it is overdue for replacement. I drive a 1998 Civic, and I replaced my radiator a few years ago because it was leaking. You probably don’t know if your radiator is the original to come with that car, but if you do know, and it is, go ahead and have it replaced. Even if it isn’t the cause, having a new radiator in there, along with new radiator hoses, can give you some peace of mind.

Perhaps you should look for a “radiator shop,” one that specializes in cooling system problems.

The sensor to switch on the fan is located in the bottom tank of the radiator, so if the thermostat isn’t opening, hot coolant will not get to that sensor and the fan will not come on. That could be caused by a clogged radiator, but it is just not likely that every tube in the radiator would clog up all at once. A delaminated hose could be responsible instead of a thermostat but the mechanic would have to remove the hose to inspect it.

The fans should come on when ever you select the AC so that is an easy check for you. Just open the hood and turn on the AC, if both fans come on, then they are OK. When the car is fully warmed up, feel the top hose and the top of the radiator. If they are cold, then its a flow problem, most likely the thermostat, but could be something else. I’d go with the third mechanic.

I second @Whitey 's advice about the radiator shop. In my experience, those places – since that’s their speciality and they do it all day every day – usually the folks there know what they are doing and how to go about to diagnose and solve an overheating problem that is stumping other mechanics. They can also fix a leaking or otherwise broken radiator for surprisingly cheap price too. In a lot of cases you’ll do better having your local radiator shop fix your radiator than buying a new one. Especially if the leak is at the joint between the metal part and the plastic part.

O have the 9i ex and was having overheating problem i changed radiator radiator fan all hoses thermostat and waterpump and it “overheats”? I didnt want to chase the problem just wanted it fixed but that didnt work for me

Michael , you just tagged on to a 7 year old thread and your post does not make sense . If you have a problem and need help just click on the New Topics button and start your own thread. State your questions clearly.

Stop throwing parts at the problem and diagnose it. Pressure test the cooling system and flow test the radiator, and if you can’t find the problem, you might need a new head gasket.

1 Like