ok 99 civic dx, ls-t..

the car overheats at idle on hot/humid days, but if i rev it, the temp goes right back down. and it does it if i am on the highway over 4000 rpm. the temps are fine at night, zero problems.

anyone have any idea whats wrong? i don't think thermostat cause both upper and lower hoses get hot. are these symptoms of a clogged radiator? water pump?

i doubt its a headgasket cause wouldn't it overheat all the time then?

 

did you check all of your grounds? my car had the same problem and found out that it was a bad ground.

 

grounds are good. fan is operational.

 

sounds like a water pump. Not competely positive, but your also boosting and i know nothing about boost problems. Not saying its an isolated boost problem but...you get what im saying.


Modified by JDM knowledge at 9:20 PM 6/20/2006

 

1.) Pressure Test your system
2.) Pressure Test your cap
3.) Flush your radiator


It could be water pump or radiator

This sounds stupid, but make sure nothing is blocking your radiator.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kyden &raquo;</TD></TR><TR><TD CLASS="quote">ok 99 civic dx, ls-t..

the car overheats at idle on hot/humid days, but if i rev it, the temp goes right back down. and it does it if i am on the highway over 4000 rpm. the temps are fine at night, zero problems.

anyone have any idea whats wrong? i don't think thermostat cause both upper and lower hoses get hot. are these symptoms of a clogged radiator? water pump?

i doubt its a headgasket cause wouldn't it overheat all the time then?</TD></TR></TABLE>

i'm in the same boat right now on my 96 accord...
i've changed everything form t-stat to rad cap to fan relays and the symptoms are same as yours...

i was told that there was coolant in the emmissions...head gasket needs to be replaced...

 

try to bleed all air out of system.. also on mine since my turbo is close to radiator i had to make up some custom" heat shields out of sheet metal. i bent them around the mani and turbo and that stopped my overheating problem completely. i think it was heat soaking the rad b 4

 

what kind of computer are you using?