2005 Camry Runs Well, doesn't overheat, but coolant disappears

Question

3 times now, in the last 2 weeks, I've added coolant to the reservoir on my 2005 Toyota Camry (125k miles) and after a few minutes of driving, it is gone. The car runs fine. Has never overheated and the gauge is in the normal range. I haven't been able to find any visible leaks, but I need to look more. My mechanic can't get me in for 20 days.

Quite awhile ago, I did notice a puff of white smoke every time I first started the car. But other than that, I haven't seen any of the signs you're supposed to see with a coolant leak. Oil looks normal, not milky. No steam from engine compartment. No puddles under car.

What should I be looking for or inspect? Is it safe to drive (in terms of not destroying the engine)?

Answer 1

Considering you're not seeing steam, leaks, nor milkshake for oil, I'd suggest your only other alternative is a blown head gasket (or on a rare occasion, cracked head or block). It has to be leaking out somewhere. Into a cylinder seems the most likely. Beyond disassembly, there'd not be much else to look at. If your felt like you needed to, you could get a coolant exhaust gas tester, which will test for the presence of hydrocarbons in the coolant system. When the cooling system is behaving normally, there won't be any hydrocarbons present. You could also try and pressurize the cylinders and see if you get coolant back flow and/or bubbles out of the coolant cap area.

As far as is it safe to drive? It would be safe for you to drive it if you keep up with the loss of coolant. If you are seeing the coolant disappear in short order after filling it up, you probably don't want to drive it too much or too far. If it goes too long and you lose too much coolant, it will overheat at some point, which might cause further damage.