so i bought a 97 honda civic dx. the kid i bought it off said he changed the headgasket water pump, dizzy cap rotor and got the head machined..... when i got the car temp gauge didnt work changed it got it working car ran fine.. one day while i was driving and the car shut off and started steaming. i looked under the hood my overflow was backed up and black. i had no bubbles on my oil dipstick. i took it to my friends shop he said the radiator cracked and was mixing with the tranny fuild. i change the radiator flushed the motor and drained the tranny and refilled still backing up in to the overflow(just antifreeze now). i changed the thermostat,the sensor on the thermostat housing and the temp gauge on the block. still backing idk what to do...i can have the car idlen for long periods of time nothing..as soon as i drive it backs up.. i jacked the front end up when i bleed the system...turned the heat while doing it to... i read a post about it could be a bad overflow tank i just checked it and when i turned it sideways it did have a leak from the cap. could this cause this or what else could it be...

 

Compression test the motor. Its likely the gasket isnt sealing.

 

Probably bad headgasket

 

Yup! Combustion gases leaking in the coolant system backing the coolant out to the overflow. Does it get drawn back in when cold?

 

It SOUNDS like exhaust is blowing into your cooling system. BUT you should have it compression tested to be sure.... which you should definitely do.

ALSO On a 97 Civic, definitely use a Lisle Radiator Funnel, any time you're messing with the cooling system. It's the only way to properly burp the air out of the system, and it works automatically using simple science so that's a plus. I ran into a cooling problem with my reservoir boling over all the time and it's the Radiator funnel has helped for sure for Phantom cooling problems! Now wait for someone to chime in on me being an idiot...

3..2..1..

 

No it doesnt drain back down it stays there

 

I just drove it today without my heat on because its nice out and no back up... 😩😩😩😩

 

My car had the same symptoms as yours and it ended being a blown head gasket.