roverben

My 99 Civic SI have a problem that's causing the overflow to always fill up. I have changed the thermostat ( got one from the dealer) and had a serious air lock in the cooling system. This was causing the temp gauge to go red. So i had my friend who's a mechanic bleed the system. It worked for about a week and now it's doing the same thing again. I then changed the rad cap yesterday and the overflow is still filling up. There's no antifreeze in the oil and no white smoke coming out the exhaust, which means that the head gasket is okay.So should i now trying a complete system flush. Any help would be appreciated.

Stock 99

Just because your oil hasn't 'milkshaked' doesn't mean the head gasket isn't blown. You should try something like this.....

http://www.arrowheadradiator.com/hea..._leak_test.htm

Other than that I'd check and make sure the rad fan is working and the coolant is being circulated by the water pump.

... but if the system was just bleed then those 2 things should should have already been checked.

matthew_burnett

on my d16y8 I have had the same problem numerous times. it has always been the head gasket. never had oil in coolant or coolant in oil. it has always just been exhaust gases in my coolant. start the car and watch your overflow, if you get air bubbles in there I would replace the hg.

roverben

Thanks guys. If it comes down to doing that kind of repair i might consider changing the motor. Is there a better motor than the D16Y8 that i can use with little or no modification at all.

rekomstop209

I have to say it really sounds like your head gasket is leaking, I literally had the same problems with my D16Y8 and it did turn out to be a leaky HG. Like you, I was skeptical because of no obvious fluid exchange.

A very cheap way to know for sure is to get a radiator sniff from a smog station, it costs about $20. If the find any hydrocarbons, HG is leaking. You can drive the car like this for a little while if you keep the RPMs as low as possible, but get the HG swapped ASAP and don't forget to mill the head (very important!).

It's also important to consider what caused the HG to leak in the first place. It could very well have been the air bubble that caused your engine to overheat and your HG breach, or even worse, crack your head.