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Extremely frustrated! Overheating with no diagnosis

So this just began recently and it has been such a pain.

My car overheats when I slow down or stop. It does not overheat while I’m on the highway and it cools as I drive. It overheats when I stop and I check the radiator after it’s cooled and it’s empty! I always have to refill after each time I drive. The reservoir is always full, but the radiator remains empty. No smoke out of my exhaust. No bubbles when the car is on. The mechanic replaced the water pump and the timing belt. After he let the car sit for hours while on and it did not overheat. The car was great after for about a week. I drive for work so it last a day of work. Before it would overheat either to or from work…depending on when I last filled the radiator.

After it was “fixed” I drove a lot more than usual…it lasted. THE SECOND I begin to drive home, it overheats. I look at the radiator…EMPTY. I managed to get home, but now my mechanic can’t find a reason for my car overheating. He did the pressure test, fine. No bubbles in the radiator, no white smoke, no coolant on floor or in the oil. I just replaced the radiator cap and lately it’s been getting worse.

It barely lasts the drive to work now.

I need help! I truly need help. Anything is welcomed and will be greatly appreciated!


The radiator was replaced toward the end of last year and it was working fine until recently.

You did not tell us about your car, what year, how many miles? The symptoms all point to a leaking head gasket, very common with Hondas, 10+ years old with 125,000 miles or so. If the engine has not been damaged by water in oil it is worth the $ to fix the head gasket. The engine is robust and will last a long time.

It’s a 2004 Honda Civic with about 155,000 miles on it. My mechanic said that he doesn’t think it’s the head gasket.

I went through this with my daughter in laws 2004 Civic, your experience was exactly the same as hers and a new head gasket fixed it.

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Ugh, I was extremely worried it was the head gasket. Is there a test that he can do that will confirm that it’s the head gasket?

One would assume the mechanic done a leak down test to check for a bad head gasket. (?) and a coolant system pressure test. (?)

Edit: If not…it’s time to find a different mechanic. It should have been done BEFORE he replaced the water pump and timing belt.

I did see him do the pressure test and he said the system was mine. The cap had a small leak, but I replaced it last week.

I don’t know if a leak test was done. What does he have to do? I usually stand there and watch.

Leak down test is just one of several means to check for a blown head gasket. Here is a link to some other ways to check for it? Your mechanic would know about these.

Ive seen him do some of those and he checked everything. No milky oil, no bubbles at all in the radiator. What I did find weird is that I tried to refill the radiator and trying to eliminate the air bubbles, it seemed as if the radiator wasn’t filled up. I would press the hose near the radiator opening and squeeze to remove air bubbles (as he taught me). Bubbles would come out, but the radiator didn’t seem to fill up. I found that off.

Does your car have a temp. gauge of a warning light? if either of these show your car is overheating, are your radiator fans on? You don’t need the fans on the highway, you only need them to force air through the radiator when you speed isn’t doing it. Your fans may not come on when your radiator is empty because the temp. sensor may not be surrounded by hot coolant anymore.

There are only too possibilities, either you have a coolant leak and your car is overheating because of low coolant or something is causing your car to overheat and push out coolant

Sometimes head gaskets only leak when the engine is fully warmed up and under load, some times water pumps do the same thing- look and see if the inside of the weep hole is the same color as the coolant. There are test strips to see if your coolant is contaminated by exhaust gasses but you have to have coolant that was in the radiator when it overheated.

He checked the fans, he said they work. A light? I don’t know. It’s jusy the arrow? I’m sorry, I’m not sure if I’m understanding the question. My mechanic said that he would suspect it would be the head gasket if my car would overheat when I drive. It overheats when I stop or slow down. When I’m driving, it cools down. Sometimes, if I’ve been going slow for too long (more than a minute or so) then it will just keep getting hotter until I pull over.

Yeah I think you’re looking at a head gasket. On mine, it would be fine on the highway but not in town. The air bubble from the leaky head gasket would prevent the coolant from flowing through the engine. Then at highway speeds there would be enough circulation of the coolant to overcome the bubble and the temp would be fine.

Did you see your mechanic use this . . . ?

That’s what I would use to check for combustion gases in the coolant

I agree with the others . . . sounds like your head gasket’s done for

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I would assume that sooner or later the thing just has to be full. The bubbles that come out while filling the radiator are normal, just displaced air. Perhaps you are filling too fast. Unless all air is removed from the coolant system you may have continuing overheating problems. You mentioned “hose” are you using a water hose to fill the radiator? You should use the proper mixture of coolant and water and not plain water. How many miles before the radiator is empty?

Edit: By the way, should the car start overheating again, turn the heater on full blast. It buys you a little time to find a save space to pull over and stop.

No, I haven’t seen him do that.

Yeah that’s how mine is. It usually last about 30 mins because that’s how long it takes for me to go to work. When I get off, within a couple of minutes it’s already starting to overheat.

I had a Plymouth Sundance years ago with the same exact symptoms. It was the head gasket. 3 times! Seems Chrysler had lousy OEM gaskets. Me and my brother-in-law replaced the third one with Fel Pro and no more problems. I doubt that Honda has the same issue with theirs though.

db has given you the best advice for a real diagnosis. One thing you can do at home is to pull each of the spark plugs and examine the porcelain insulators. Burning that much coolant, they will be bright white, almost like new, as opposed to a light tan or darker color for normal operation.

In that case, I’m wondering just how your mechanic ruled out a bad head gasket . . . ?

That tool is quite cheap, chances are he’s got one lying around in the shop

It only takes a few minutes to set it up and get your results

The idea is . . . if the fulid stays blue, all is well, if it turns yellow, you’ve got combustion gases in the coolant, and they have no business being in there

There are other ways for combustion gases to find their way into the coolant, but in your case I believe the head gasket is the most likely

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