I don't know what to do!

[GMFWDFAN]

Remember my antifreeze overflow valve story yesterday? Well, if not, here's a brief overview:

I recently had a coolant flush done. Yay. My mechanic told me that I may have to add some coolant later on. I checked it the last few days, and I added a bit twice. The first time I added a bit I left the cap off, so some boiled over. I put the cap back on, checked it yesterday morning, and found that it was slightly below the full cold line. So I added some. I got home yesterday and the car left a huge puddle of coolant on the garage floor - it came out of the overflow valve.

My grandpa and I checked the level this morning, and it was fine. So I drove to school, and then today I stopped to get gas, and it did it again. Big ol' puddle of coolant, and of course it came out of the overflow valve.

It can't have possibly had that much extra coolant, could it? I got a new pressure cap, could that have been the problem?

And before anyone asks, the car is running fine. The oil is fine, no funny exhaust color, no over-heating (it got about three over the half mark when I started it back up at the gas station, but after about two minutes of driving it promptly went back down to normal). And no low coolant light either.

:???:

[SikMindz]

When flushing and then adding coolant, especially as sporadically as you are and having left the cap off, you definitely need to bleed the lines and get the air bubbles out.

[GMFWDFAN]

I should also mention that I drove it back to the dealership to get the cap, and there was nothing out of the ordinary. No over-heating or anything.

How exactly do you "bleed" the lines?

[GMFWDFAN]

Okay, I bled the air out (if that's what you meant by loosening the little bleed valve thing a little). I added a slight bit of coolant, because it really did seem slightly low.

Who knows, it'll probably throw up again, but it's not over-heating at all.

[rixGAphx]

Only tighten the pressure cap as tightly as an average woman can easily do one-handed.
Any tighter can damage or distort the delicae rubber sealing ring, detroying th pressure seal.
You may have damaged the new cap; check that it's holding pressure even though it's only a few days old.
Better blow $12 on another new one than to ruin the engine to the tune of $2000You can buy high-quality 'stant' caps at Checker/AutoZone/NAPA/etc., not necessary to feed the dealer beast.

Lack of pressure will definitley cause 'boil-over', even when the needle doesn't reach very high on the gage.

Hope this helps,
-Rick

[Nighthawk243]

Yep. Make sure you tighten it correctly. I personally liked to use the non dominant hand, it usually keeps you from overtightening it.