my girlfriend drive a 98 civic and today it started showing some overheating problems. she came to my house to pick me up and when i got in the car i smelled something and looked at the temp gauge and it was hot. she shut teh car off. i popped the hood and the coolant was boiling in the overflow tank. it appeared as though some were leaking out somewhere at a very small rate. we let it cool down and started it back up. it stayed cool for a few minutes then it started to rise. the top radiator hose gets HOT but the bottom one doesnt? i assumed thermostat but a haynes manual said if it was the thermostat the top hose wouldnt be hot and the bottom would. any ideas?

im changing the thermostat, radiator cap, and making sure theres no bubbles now. im just not sure sure thats it.

 

while its in the driveway start her up and let her idle for about 15 minutes. During this time check the temp often and see if the fan activates. If the temp rises and the fan doesnt activate come back and we can go from there.

 

hey aws140 i just recently got the same issue as u with my 96 civic n yea my car was overheating, but the temp guage is no longer overheating. What u can do based on my experience is change ur thermostats and put in fresh new coolant. Also make sure when u put in new coolant, u must bleed the air out otherwise u're doing it incorrectly. Furthermore, another thing u need to check is ur radiator fan to see if it turns on when ur temp guage is midway. Anyhow, tell me more about ur problems after u try all that and ill see wat i can help.

 

There is a good chance it's the thermostat, since the bottom radiator hose doesn't get hot.

On most Hondas, the thermostat is located at the lower radiator hose, under the thermostat housing next to the engine block. The thermostat may not be opening properly to let the coolant warmed by the engine block, to flow back via the lower radiator hose to the radiator; therefore, the lower hose is not hot.

 

change the thermostat and gasket , maybe the fan switch, which is the one in the thermostat housing , as far as bleeding air , on that model just have it on level ground , let it run with the rad cap off till fan comes on air will vent out of radiator , it may take 20 min at idle for fan if all is ok , also get factory honda parts , no vatozone stuff

 

If the upper gets hot but the lower stays cold (after about 5-10 min. of idling) the thermostat is bad. Sounds like the haynes has the two switched. If that is the case, replace the thermostat only and verify if that fixes your problem. Anything else is wasted money.

 

thermostat, i'm almost positive everything you described points directly at thermostat.

 

if you change the thermostat and it doesnt work. it could be a bad head. check your oil if it looks milky like it has water in it....

if you take to the nearest mechanic shop around they'll charged you about 600-700 bucks to rebuilt the head.

 

i changed the thermostat, flushed the engine and radiator, and put fresh coolant in there. i also installed a new radiator cap while i was at it, figured why not. i let the car get to operating temp with the radiator cap off to let the air bubbles get out.

since then we have driven the car for 200-300 miles. it has acted perfectly since.

my concern is this, when i noticed the difference in temps of the radiator hoses i instantly thought it was the thermostat. i went to the auto parts store to do some research. i looked through the haynes manual for all the info i could. when i read the thermostat symptoms it said the bottom would be hot and the top cold. i thought this was very odd, but i took their word for it. thats what threw me off. bad info.

thanks for all the help guys.