Hi there Honda-tech.

Problem I had today was I was driving for about an hour and when I came to a stop light the car just started to overheat. I pulled to the side of the road and checked to see if there was any coolant in the system, the overflow tank was full and the radiator had fluid as well.

lately I've been having an issue with coolant spraying out of the overflow tank but replaced the radiator cap just recently which seemed to help with that.

I was able to drive the car back home with the heat set on high so I'm pretty sure my thermostat is still good.

so the question is, why would the engine overheat with coolant in the system.

By the way I drive a Civic EX with 169,000 Miles on it

 

Does your radiator fan turn on?

 

the fan does come on, i think it comes on when the temp is over 205F, i had my obd2 reader with me to check the temp and thats when it seem to come on

 

You could have air in your system, also how does your oil look, if it looks milky its time for a head gasket. Pop the hood and turn your ac on, the cooling fan should kick on.

 

I'll try to bleed the cooling system tomorrow and do a block test to see if I have a bad head gasket. The oil when I checked it was a light brown color, when I turn on the ac it turns on both fans.

Another question is that when I was running the engine without the radiator cap on at about 3000 RPMS coolant was spewing out of the spout, is this normal? Would this confirm a bad head gasket?

 

The head gasket is almost surely blown, but try replacing the thermostat first.

 

Thanks Ron, I replaced the thermostat about 6 months ago. Sounds like its the head gasket for sure then.

Thanks for your help everyone, sounds like I got a new project to keep me busy and learn something new

 

I fought an overheat problem for a few weeks.

Replaced the thermostat, fan switch, did the process for getting air out of the system.

Mine would only start to overheat while stopping.

Finally I rented a pressure test system and put it on. Couldn't build any pressure on the system. Where I thought my coolant was just blowing out the overflow, it was actually coming from a hairline crack on the plastic top of the radiator.

Go get the pressure tester and see what happens