Head gasket leak detection E36 M3

One of several methods to check and see if the head gasket is leaking on a car.
Combustion Leak Detector
kit I used:
www.amazon.com/dp/B0007ZDRUI/...

[@maikeru01]

if your thermostat is installed, you have to run the car for a bit to get it up to temp, otherwise its not circulating. it would be pointless to just turn on the car and test straight away. since yours is a race car i am guessing you dont have a thermostat. i learned this on my 325i. you can test all you want with the engine cold it'll never turn yellow. but give it a few minutes to warm up so that thermostat opens and then the exhaust gases start going into your coolant reservoir.