Rep Power: 0

I have a 2003 Civic that overheated and blew coolant through the overflow tank. I lost and replaced thecap to the overflow, but it’s stripped and doesn’t seem to be air tight. This is supposed to be a closed system correct? (As in there should be no air in the system) I also replaced the radiator cap.

Reading the forums points straight to the head gasket so I did the block test (twice) to check for exhaust gases in the coolant system, and it passed, but with everything I’m reading it could still be the Head Gasket? I also don’t have coolant in the oil, white smoke, or oil in the coolant.

Currently I can drive it 40 miles to work with no issues untilI get off the freeway and sit at a stoplight then the temp will start to rise. I’m not sure what to do or check next? Thermostat, water pump?

 
Rep Power: 517

Typical head gasket symptoms.
If it overheated bad enough, it could have warped the head.
If it boiled coolant, it could have ruined the radiator neck where the cap must seal, now it can't hold any pressure at all. Steam erosion ruins plastic in a hurry.

The cap for the overflow bottle probable never screwed on real well, and it is NOT supposed to be airtight, but you can buy a new one if it is damaged.

I don't rely on a commercial "block checker", it isn't accurate or reliable enough for me.
I pressurize cylinders to prove a leakage problem.

HTH

 
Rep Power: 0

check for upper & lower HOSES. if one of them when touchedv is showing cool but other one when you touch it is showing hot, then believe it its the radiator. Im working on completing all sorts of tests on 2003 Honda Civic EX 4 dr sedan. You do this with RADIATOR CAP REMOVED.
I will report as soon as possible.

 
Rep Power: 0

I am DILIGENTLY TESTING/CHECKING TO SEE IF IT IS INDEED THE hg

 
Rep Power: 0

Also check to see if end of hoses show wet when u touch it.Both upper & lower hoses

 
Rep Power: 0

Attached is the pic for wiring to Map Sensor? To replace it, AdvanceAuto describes item as Map Sensor Harness for 685 Haywire Ignition System, is that what it is? I suggested it be replaced versus repaired? $ 35 cost.

What do you think?

 
Rep Power: 0

I moved my post on HG elsewhere. sorry

 
Rep Power: 223

I have an 02 civic ex and this was happening to me. It kept overfilling the overflow tank and running hot. Took it to a shop and they did a leak down test and it passed. They tried to fix it twice and couldn't. The third time they decided to replace the head gasket and that fixed it. I also didn't have white smoke, oil in the coolant, and didn't notice any coolant in the oil but I guess there was.