Ever since summer hit my car will get 3/4 or more of the way to max temp. If i crank on the heater it will drop to half in a few seconds.

Usually only happens when cruising on the freeway in the day time arizona heat. Is this a bad thermostat, too small radiator, what?

2000 civic si motor.

 

what rad are you using? thermo could be going... check that.

 

thermo could be going... check that.
first i'd check ...
got enough coolant? any hose leaking?

 

Is the motor stock or turbo?

Have you bled the system to make sure you don't have any air in the system at all? Have you either jumpered the fan switch to see if the fan is working or just turned on the AC to see if it comes on?

Is the bottom hose on your radiator getting warm or staying cold?

 

thats a thermo problem. change thermostat and you should be good...
OEM parts are the best!!

 

little radiator is so fun to look at but yeah i swear it sucks. i vote for thermo too though :-D

 

Ok, so i have decided on the thermostat as well. I was thinking of gettin a 160 degree low temp themostat for 20 bucks. Good idea or stick with oem?

 

motor is stock and the fans do turn on. ill check the hose soon.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by R.S.AKIMOTO &raquo;</TD></TR><TR><TD CLASS="quote">thats a thermo problem. change thermostat and you should be good...
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How is that a thermostat problem? You say it with such conviction, explain to me exactly how you know that. When a thermostat fails it almost always fails open, they are designed to do that. So if the thermostat was bad you are almost always guaranteed to be running cold or with fluctuating temperatures. Not an overheating motor.

Other problems such as a bad fan relay switch, old dirty coolant, clogged rad fins, partial obstruction in your coolant passages/lines, and air in the system is normally associated with over heating.

OP: it would be a lot of help if you could pin point exactly when it does this. If you let your car idle for a while will the fan engage?

 

OH crap i got the same thread man thats why i got no answer

 

I don't know how modified. If it is then the more parts to inspect and eliminate as the cause. I say this as oem parts is fool proof especially on a honda.

See which cooling parts are non original (these would be the ones I would suspect as the cause).

For non stock parts I would start at assessing if they are old, worn and requiring replacement. Eliminate these parts by replacing them with oem (as they are available as second hand and for sure its going to work fine with the rest of the cars cooling system)

If all are stock then I would inspect the cooling parts as above if they are old, worn or damaged and replace accordingly. Usually a non rusting radiator would not be the cause of an overheat. You can try removing the thermostat and using the car. If it still overheats then I would suspect that it could be a leaking head gasket problem.

 

get that Muuuuugen thermo
hahaha
i think its a waste of money but if you need one, you should upgrade the jdm factor.

 

I replaced the thermostat and drained the coolant and refilled. Car does not over heat when cruising down the road. It is at a good below half on the temp gauge. Now, though, my car will occationally overheat at an idle but cool off when driving. Must be fan related. What should I check. It does turn on.

 

[QUOTE=old man neri]

How is that a thermostat problem? You say it with such conviction, explain to me exactly how you know that. When a thermostat fails it almost always fails open, they are designed to do that. So if the thermostat was bad you are almost always guaranteed to be running cold or with fluctuating temperatures. Not an overheating motor.

QUOTE]

funny...my car kept over heating till i replaced the thermostat and it was golden and haven't had a problem since

but bump for this guy