I'm a bit puzzled but as the title states, If I top off my coolant (cold) it looks like it has a major leak, pools everywhere, but if I let it sit at the bottom of the reservoir, it runs ice cold (195 on stock temp stat+dexcool) and doesn't drip anymore.

Anyone experience this before? Its hard to find a leak that doesn't always leak.

 

I would suggest that this is a false hope. The sensor you are depending on pokes down thru the roof of the intake manifold. It expects to be in full contact with the liquid. If coolant level is low (and you may have the under dash gurgles of bubbles in coolant to go with it), that sensor will be in hot vapor. As an example, a pot of pasta boiling on the stove. hand can be held over pasta in the steam, but shove hand into the roiling water, and you'll see the difference (do not do this kids, and don't let you little sister do it either).

So running this way you could have damaging temp level and not realize it, even with a scanner monitoring the OBDII port.

A couple of things to try - top up (to a reference line, not 100% full), and zip tie a paper towel to the end of the overflow line. If coolant cap is venting at 10 PSI, instead of 18 PSI, then that could be part of the problem. You can also rent/borrow a coolant pressure tester, pump up to 15 PSI, and let it sit for 30 minutes. It is easier to find the leak when engine is off.

 

Good stuff there, from Buzz. No need to elaborate. Listen well and heed his advice.

 

"You can also rent/borrow a coolant pressure tester, pump up to 15 psi, and let it sit for 30 minutes. It is easier to find the leak when engine is off."

 

As Buzz mentioned, I would replace the coolant cap first then see what happens.

 

And Dexcool... is not cool. Can turn to dexmud and is known for eating coolant caps. Invented by this guy's brother.