mhillips

I have a 1999 Civic LX with 145k miles and Im having the hardest time fixing an overheating issue. The car only gets hot after I've driven around the block for a good ten-fifteen minutes with the AC on while I am idling. When the car gets hot, the heat meter goes all the way to H (hot). The second I turn off the AC and turn on the heater it gets colder. I've noticed that it will sometimes get hot if I do not have the AC on and I am idling, but it always does when my AC is on. If I turn my car on and idle without driving and turn on my AC it doesn't seem to really overheat, although I've only let it run and tried this for like ten minutes or so.

I replaced my thermostat ad its gasket about a month ago because I thought that it could be the issue but to no avail. I pulled the thermostat out yesterday and took off the gasket, put it in a metal pot, filled it with water and heated it up on my stove. A little bit before the water started to boil the spring pulled down and the thermostat opened up. The thermostat is rated for 170 degrees F and even though water boils at like 212 F or something like that I figured it was probably ok and my new thermostat wasnt sticking or defective. I took my car to sears and had them run some tests and they said I failed the coolant test, which is a meter/pump/hose that is fed through the radiator and test for pressure. One day when I was driving on the freeway I stated to smell anti-freeze and when I pulled over and popped my hood, there was anti-freeze all over everything. It looked like it was coming from my radiator cap.

So I thought that it might be related to my radiator. I pulled off my cap and I noticed the seal was kind of FUBR and thought maybe somehow the pressure in my cooling system was cattywampus. So I bought a new radiator cap and surprisingly enough It did help. My car seem to be running a little cooler until the overheating issue occurred again. Although this time, it took much longer before it overheated. I figured since I had recently acquired this 14 year-old car and the previous owner didnt maintain it that maybe the whole radiator was having issues. I pulled it out and noticed that about every fin was bent to heck and than it was dirty and caked in grease. I assumed it was probably a 14 year-old radiator and I decided to trash it and buy a new one. So I purchased a new, installed it, filled it with 50/50, turned my car on, turned my heater on, and then I waited for like 15 minutes, turned my car off, and put the radiator cap on. I drove my car to work and it was driving fine the entire way until I pulled into the parking lot and idled for like a minute or so, then it got super hot again.

So I thought maybe my hoses are bad. I pulled off the upper and lower radiator hoses and ran a garden hose through them. I didn't see any holes or rips or cracks and water flowed through them fine. I also check my tranny lines and replaced my tranny fluid, even though I didnt think it would make a difference, I figured I might as well check everything connected to the radiator. My overflow tank looked ok, there werent any cracks or anything although I personal hate how the lid sits on it, but I figured that shouldn't matter too much because the tank isnt pressurized (or at least I don't think its supposed to be/mine isn't).

So I thought maybe my cooling system was clogged. I drained my cooling system, bought some radiator/cooling system flush stuff from the local auto store, poured it in my radiator, filled the rest of my radiator with some water, let it go though my system let my car run for 15 minutes with the heater on, drained my system again, and then filled it up with 50/50. My car would still do the exact same thing.

Next I thought it could be the head gasket. I checked my oil and it looked fine, it wasnt frothy or looked like creamy coffee or anything, it just looked like oil. I've never noticed my car emitting smoke or any sweet smells from my exhaust and my car eventually can cool down with the heater, I thought if I did blow the head once my car got hot I couldn't stop it. Just to be safe, I drained my cooling system, poured in a bottle of Barrs Head gasket sealent, which cost me an arm and a leg and supposedly had a bunch of flakes of stuff, and I followed the instructions on the bottle. My car was doing the same thing.

I check my AC compressor fan and my radiator fan. All fuses and relays looked good and both seemed to work, although it seemed like it took a while for the radiator fan to kick on. Like I had to drive around a good 10-15 minutes before it would kick on, it wouldnt turn on just idling after 5 minutes.

The only things I can think of are this: I have a bad water pump, theres a leak somewhere else, maybe somethings wrong with my radiator fan, or maybe my head gasket is blown or I have a crack somewhere and that sealant failed. I'm unsure if it is the water pump because the car isn't leaking onto the ground anywhere and the car doesn't really make any unbearable noise. I read online that when the pump goes out, it will usually make a grindy noise and it gets louder as I accelerate. My brother used to be a mechanic for sears and he told me that sometimes the pumps fail silently but he couldn't tell me anything about my car. Sometimes when im driving with the AC on I hear an occasion hiss/slight grindy sound and it sounds like its coming from the passenger side, but it isn't constant and isnt super loud. You cant hear it from the outside of the car.

I'm not sure if it supposed to take that long for a radiator fan to kick on, and was thinking that maybe theres like a sensor or something I need to replace because it doesn't cue up when its supposed to. I also tried massaging the upper and lower radiator hoses with the radiator cap off, engine on, and my heat turned on and my coolant began to bubble until it got all white and foamy. Then it turned still and look like the head on a beer or bubble bath or something and whenever I'd wipe it all the coolant would bubble until that happened again. Is this normal? I'd assume that the coolant would be a little more still and would not be foamy and would look greenish-clear. I also noticed the upper hose was getting pretty hot (which I would assume) but my lower hose was remaining pretty cool. Is this normal? I would think that if hot coolant was running through the system all the hoses would be hot but I don't know enough about cooling systems to know.

I'm not sure what to do now and rally don't want to keep spending a ton of money. Im afraid to open the head and fine out it was fine the whole time and then have a hell of a time putting it back to and having to replace the gasket now because I opened it up, and I'm afraid to buy a new pump and spend the afternoon putting it in and find out that I wasted more time and money if it was something else.

I'd really appreciate any help, tips, or advice. Thank you all so much.

go-part

Has your temp sensor been checked?

http://techauto.awardspace.com/overheating.html