L31MaxExpress
I'm Awesome
A more involve method that I have had to resort to a couple of times to check for cracked heads and blown head gaskets that do not show with a block gas test. Get a cooling system pressure tester. With a cold engine, remove all the spark plugs. Hook up the tester and pump the cooling system up to 16 psi. Walk away for several hours. Check the pressure when you return. I had a Sentra that would only overheat when driving and it would blow coolant out of it. Also had a hard start and rough idle after sitting. Well it passed the block gas test multiple times. I pulled the plugs and pumped it up. Ended up letting it sit overnight. When I looked into the spark plug holes, cylinders 2 and 3 had coolant standing on the pistons. On a van you cannot easily see the inside of the engine through the spark plug holes. However if you crank it over with all the plugs out and the ignition disabled, if coolant is leaking into the cylinder spinning the engine over will spit it out of the leaking cylinder.