Rep Power: 0

Ok so here are my symptoms:

* occasional very very small bubbles coming up in coolant, even after bleeding system for a half hour.

* slight amount of pressure escaping when i remove the radiator cap, even when cold after sitting overnight

* used a "block leak test" from autozone with the blue liquid that is supposed to turn yellow if there is a leak. Well, mine turned green (no it did not suck up coolant). To me this is kinda inconclusive. Maybe this means a very slight leak?

It does NOT blow any smoke, nor does it overheat, or lose any coolant. Oil looks fine, coolant looks fine.

It DID come close to overheating due to a bad thermostat a few weeks ago, but the needle never did go all the way to the very top. It went up about 7/8 of the way though, a couple times. Not sure whats really defined as overheating.

After I replaced the thermostat all was well for a few weeks, until it started to overheat again at idle with the A/C on. I then noticed the overflow tank was full and had spewed over. I replaced the radiator cap and all is well again, except for my small remaining symptoms mentioned above.

Any thoughts?

 
Rep Power: 313

If your overflow spewed over it's a headgasket. If you are unsure check the link in my signature but I'm about 99% sure you need to replace your headgasket.

 
Rep Power: 0

well i've read a bad cap could cause it to overflow also.

I should also note I've driven it for 2 days since replacing the cap and the overflow tank level is exactly where it was when I replaced it.

 
Rep Power: 313

It could be the cap but it's VERY unlikely. You generally need some type of force to displace the coolant into the reservoir (exhaust pushing it's way into the coolant system through failed gasket).... A simple leak or failed cap isn't enough. Give it a couple weeks and it will probably start doing it again. I hope for your sake it doesnt! All I can do is tell you what happens 99% of the time. I have seen the rad cap fix the issue but only 1 out of about 500+ cases I've seen on here. You can always try the head gasket test again for good measure.

 
Rep Power: 367

I did not do the gas test, but since i was close to the timing belt, i did it anyways. Overflow overflowing literally. no overheating, though.
I drove for 2 months that way, last trip was 1200 miles, but again, it WAS NOT OVERHEATING, so be prepared to change it... Otherwise, you will need to plain the head for sure. How many miles? if close to timing belt, do all at once.

 
Rep Power: 0

Yeah i changed it @ 115k. 155k on it now. I've been pondering over if i should do it again, but by time it really needs it i probably won't even own the car anymore. I know it wouldn't really be any extra work, but it would be an extra $100 or so

 
Rep Power: 313

40k it's a tossup. I probably wouldn't change the belt.