bstudey01

I was a bit low (8oz) on coolant the other day and just used one of these to test for combustion gases in the coolant system. Fluid changes from blue to yellow in presence of carbon monoxide I beleive. My question is that we have no access to radiater directly, I put it into the overflow tank to test, is this okay??. It pulled air up into it and no color change. Can I be confident that there is no head gasket leak. I have no other signs of head gasket leak and cannot see coolant leaking externally, ic system is split. I know I can have it pressure tested or buy a kit to do so but they are much more expensive.

3BNick

Yes, testing at the expansion tank is acceptable. As long as the car was running while you were conducting the test you are fine. The next step is a pressure test for sure. There are also UV dyes made for cooling systems you can add if you want to get all "CSI" on it. It could be useful if you have a very small leak that would otherwise go unnoticed

bstudey01

Cool, that's what I thought, I let the car run for 15 minutes and tested multiple times. Also checked at the tailpipe and the fluid immediately turned yellow. I think I'm good. Maybe next time I get down to speedriven I will have them do complete compression/leakdown and pressure test of cooling system just to make me feel better. I have never been so crazy about any other car. I mean I drove a beater saturn I had for like a year with a cracked head. Coolant would turn to milk every week or so and I would have to flush it out.