I have a 98 civic with 170k. I have noticed that it bubbles in the coolant overflow. It doesnt smoke,hesitate or go through coolant that I can notice. Temp and heat are good. I have heard bubbles mean the head gasket is bad. Is that true or myth? Thanks

 

looks like it. had some problem last month. changed head gasket n timing belt. might wanna look into timing belt if your going through the hassle

 

Wait. . do you mean bubbles as in escaping air or as in boiling?

 

No boiling. If i unscrew the overflow cap and pull the hose up a little bit I see bubbles. I can hear them also when the cap on. The checked again tonight no coolant loss that is noticable

 

might need a new rad. cap

 

How does a radiator cap affect boiling?

 

That isn't a Rad cap issue you getting back pressure from the combustion chamber out into the cooling jackets. Meaning the head-gasket is going bad its only a matter of time before it gets worse. The coolant loss at this moment is minimal because its being burned up with the exhaust. When it does finally break though your going to have more problems than that. Back pressure or Blow-back(what real mechanics call it lol) is one of the biggest signs of a bad head gasket. Consider yourself lucky because it could have just went with no warning.

 

Thanks for the info. Guess I will be tearing it down woon