BMW E36 M3: How To Check For A Failed Head Gasket Or Combustion Leak
Here is a short video regarding how to test for a failed head gasket or combustion leak in the cylinder head. I rented a cheap combustion leak tester from O'Reilly's and purchased some leak test fluid. Follow the included instructions; if your test fluid changes from purple to yellow...you have a leak somewhere. I am testing my 1995 BMW E36 M3 but this exact process can be used for any car.
If the suction bulb seems like it doesn't want to inflate, try removing some coolant out of the reservoir. If the level is too high, coolant get's sucked up or blocks the air flow and the bulb fails to re-inflate on it's own.