ok so my civic keeps wanting to over heat only on the free way.. its a turbo b16 topmount mani.. so there is alot of heat under the hood.. it has a aluminum radiator, torque flow high performance fan (pushing) and it will still over heat with the fan on.. it will start to heat up and will go bak down it i let off the gas and let the tranny slow me down.. if i just put in nueatrl and coast it still heats up.. weird.. any ideas? thermostat it good..

 

Sounds like a plugged radiator.

 

Here are some things to try:

1. Bleed your cooling system and make sure there is NO air bubbles in your coolant.

2. Block off the open area where your ac condensor used to be with sheet metal to force air into your radiator.

3. Raise the backside of your hood up using washers which will alow the hot air to escape from your engine bay.

 

Do you have the air dam installed in your car? That would be the bige peice of plastic under the front bumper that alot of people like to remove.

are you running a full or 1/2 radiator?

how much space is there between your FMIC and radiator?

My car was showing signs of overheating on the freeway; During the day. Cold nights would not do this.

Sounds like an airflow issue at first whim; Simple to explain; if the air being forced through your FMIC is not forced to travel through the radiator; it will take the path of least resistance to get out. This would be the space between the radiator and FMIC.

Also; if your running a 1/2 radiator; blocking off a good 75% of the hole next to the radiator will help tremendously. On another note; turn on your heater full blast on the freeway; do the temps drop? While heater is on set it to floor heat, do a pull in 4th, and once you let off, do you feel a heat-rush from the vent?


Are you reading this off your dash gauge? ECU? Aftermarket gauge?

If your reading this off your dash gauge, there is a good chance your engine is getting hot, not overheating yet. My dummy gauge in the dash starts rising in temps above 217, and hits near the red zone at 225... which is nowhere near linear so you can't truely judge this as overheating per-say... just heating up.

When I removed my FMIC for a test, what would you know; no more temp rising above 65MPH.

Also, check to make sure you have the hoses for the bypass and heater core are not switched. (bypass hose being the hose from the intake manifold to the thermostat housing/water tube.

Hope it helps you!

 

i have the same exact issue.

 

Point 1 and 2 is correct.
As for point three is that is more a myth. That particular section of the car at speed is a high pressure area. An inverted scoop on the bonnet which uses air speed to create a neg pressure and draw air out like drift a drift car would work much better.

Before you would go to point three I think that doing 1 or 2 will solve the issue.

 

the intercooler is about 3-4 inches.. but why wud the temperature go down when i let off the gas and le the car slow me down?? im reading of the stock gauge..

 

If you have a blocked radiator then when the are cruising i.e low revs then enough coolant will pass through the core as the water pump is not pumping at a huge rate.

If you increase revs and speed the coolant flow through the rad cannot keep up causing overheating.

 

also if you are cruising then you may get sufficent airflow through the core.

How ever at high speed the air will find the path of least resistance and if there is no baffle where the a/c would have been then the airflow will take this path.

 

Not enough flow...... thermostat???? could have some trash in ur coolant system, is the thermo new??? check (physically) your thermostat i have had them hang up and wont open up all the way and cause this problem....

also sound like there might be leaking headgasket, had a impreza do that as well, where it would get hot while driving and would be just fine at a idle... check your rad cap also....