Rep Power: 0

In my 1998 honda civic si (canadian) I have completely clean oil and it seems like completely clean coolant, the only thing is I have to constantly top it up due to a lot of pressure and I'm assuming its going out through the reservoir? When I've let it sit for a day it still has a lot of pressure in the radiator and I'm wondering if that would be good enough to assume a blown headgasket, there are no leaks under the car, I've put paper under it and everything. It also misfires a bit during a warm start, I'm not sure if these are related or not though, any help/opinions are appreciated!

 
Rep Power: 224

Usually the D series engines don't mix oil/coolant when the head gasket goes bad. Combustion gasses leak past it and into the coolant system, that pushes coolant out into the reservoir and can cause it to overflow. The thread below is for the 7th gen but still a D series engine. You should be able to do the same tests.

https://www.civicforums.com/forums/3...reference.html

 
Rep Power: 0

Alright thank you!