mrchowmein

Wow its been awhile since I posted. Anyways, I was driving today from the Bay Area to So Cal. About 4 hours in, I glanced at my scangauge and my water temp was 190, then within a min it hit 240. I wasnt even pushing the car, the civic was rolling down a hill. Anyways I pull over to see whats going on. What I saw was the coolant reservoir was filled to the brim with coolant dripping out. I used my hand pump and drained about a cup of the coolant out of the reservoir. I let the car sit for about 20 mins. I restarted the car and the water temp stayed about 200. I tried to run the heater, it worked at freeway speeds, but once i slowed down to 30 mph, the heater started cutting in and out. I drove for about 15 mins to find a gas station and got some coolant. I left the car off for another 45 mins. I opened the radiator cap and was able to pour in about half a quart of coolant. I restarted the car, and the temp stabilized around 180-190 for the next hour. However, when I slowed the car down the engine would heat back up.

Im trying to figure out whats going on. Im thinking, its not a case of a broken water pump. From the way things look, there might be a clog in the cooling system. Im thinking the water pump was able to pump the coolant into the reservoir thats why the reservoir was overflowing. But something is clogging the reservoir coolant from recirculating back to the radiator. Thats why the radiator wasnt full. I see from other threads there might be a possible gasket issue. The oil looks brownish, not milky. The coolant is green, not brownish. So I dont think its a gasket issue. Any advice or insights on other things that might be wrong? Im thinking of flushing the system before I start replacing parts. I also changed my spark plugs on sat July 17. Do you think improper torquing of the plugs could cause this? Thanks.

2002 Honda Civic EX 4DR. Auto with 128k miles.

pjb3

The water pump never circulates coolant to the overflow reservoir. The radiator caps allows coolant to escape to the overflow when the working pressure of the cap is exceeded. If you have a 14 psi cap then coolant flows to the reservoir when the pressure exceeds 14 psi. Under normal conditions, as the engine heats up and the coolant expands, the excess coolant goes to the overflow. When the engine cools down a vacuum is created and there is a small valve in the radiator cap that allows the coolant to be sucked back into the radiator. Basically coolant flows to the reservoir only when the pressure in the radiator exceeds the rating of the radiator cap.
Excess coolant can be forced into the reservoir if the engine overheats and boils the coolant, such as if the thermostat were stuck closed or the radiator is plugged. Another way is if the head gasket is leaking and allowing combustion gases to enter the cooling system. Combustion is at hundreds of psi so if there is a leak between a cylinder and one of the cooling system passages, the coolant will be displaced by combustion gases and the only place for it to go is the overflow reservoir.
Unless your antifreeze looks like mud I would be surprised if there is a clog in the cooling system. Given the high failure rate of head gaskets in Civics I would have the antifreeze tested for combustion gases.

mrchowmein

civic ran fine today. I stuck on a new honda radiator cap and the reservoir no long fills to the top. civic idles around 190 if i have the ac on in 90 degree so cal heat. 200-205 with out ac running. urban driving around 188 and on freeway 180-195.

what temp should the radiator fans kick on? 180? 200?

Im planning to go the shop tomorrow to see if the fans and thermostat are working properly. im also gonna ask them to do a coolant check for combustion gas.

Anything else i should check? thanks for the help.

lazlong

Sounds like the condenser fan. You can easily diagnose and/or fix the fan yourself. Like about 1 minute to diagnose with jumper wires and about 15 minutes to replace. All you need is a flathead, 10mm socket,and pliers.

If it's not the fans it's probably head gaskets like you surmise.

mrchowmein

the radiator fan kicks on at around 205 degrees for me right now. I think its suppose to turn on around 180-190 correct?

when my car overheated, only one of the fans were running. Both should be running when the coolant hits a predetermined temp correct?



thanks.

lazlong

Sorry, miss-read. Sounds like thermostat. Cheap part, two bolts and a hose to remove. It's on the front of the engine, where the bottom hose goes into block.

Only the radiator fan comes on at operating temp (starts to open @ 169-176F, fully open @ 194F). Condenser fan comes on when your A/C compressor cycles.

pjb3

I doubt it is the thermostat. I thermostat would not cause a car to run fine on the highway and overheat when you come to a stop. When a thermostat fails it is usually stuck open or closed. If it is stuck open the car will not reach operating temperature in cold weather and if it stuck closed the car will overheat in a short time.

Since you replaced the radiator cap you might just try that and keep an eye on things for a while. If the spring in the radiator cap had weakened it would allow the coolant to boil at a lower temperature and the coolant would go into the overflow reservoir. A bad radiator cap will cause some coolant to overflow but a bad head gasket keeps letting more and more combustion gas in and displaces more coolant.

mrchowmein

back from the shop, there is exhaust in the coolant. Possible crack in gasket and warping of head. Ill find out friday what is the exact damage when the mechanic cracks open my engine. funny thing, there was an exact honda civic to mine (2002 satin silver ex) receiving a new gasket there at his shop. gonna cost 700 to fix including milling the head. i would do it myself with my dad since he replace blown gaskets before, but im in an apt right now and im moving across state in 2 weeks. is $700 usd reasonable? this is an independent honda shop. Ive seen people pay upwards of a grand.

the question now is what is the most likely cause of the blown gasket? just a poor gasket from honda? the mechanic suggested that since only 1 of the fans were running when my car overheated, that couldve been the culprit. thanks for the help everyone.

lazlong

Read in another thread that this a common problem. Don't know about the price though.

mrchowmein

yea common. kinda like the auto transmission 2nd gear clutch pack. ive beenn living in fear that would go one day on my civic and its held up well. lets hope that continues. I consider the 98-03 years for honda as crap years as almost all their cars had tranny issues whether honda admits or not.