M20 No start

[350iowner]

Let me tell you a story.....

I noticed a small coolant leak on my radiator for about a month so I went ahead and ordered a new radiator. No problems at all got it installed and no leaking at all. I go on a 600 mile journey to the Tail of The Dragon with some friends and it did great! That next week I was sitting in traffic and notice my temp gauge went immediately to red and then right after dropped back down to normal temperature so I babied it and was going to look into it after I got home. 5 minutes later I get a big backfire and it dies. I check the coolant and there is none in the expansion tank. I am puzzled. I take the intake boot off and it is coated in coolant. So I assume it is the intake manifold gasket or throttle body gasket. I tow it home because it won't start and I replace both gaskets. Now it won't start at all. I checked fuel, spark, and compression. All good. Did a smoke test and had a couple of leaks. Fixed all the vacuum leaks. Still no start. Replaced the crank position sensor and still no start. I also am not getting a CEL so I am at a loss. Hopefully someone can help. I need more m20 in my life

[master quon]

Not sure why you'd replace the intake manifold and throttle gasket for a coolant leak. Coolant shouldn't be flowing past those gaskets. If there was coolant in the intake boot, there is another gasket on the throttle body for the coolant hoses on the side to keep the throttle from sticking when its cold. that would be my best guess. as to the no start, i'm thinking you still may have coolant in your engine if it was flooded. did you check your oil to make sure it's not contaminated with coolant? if not that, them maybe you didn't put it back together properly? try taking it apart again, you might find the problem.

[101]

pop the valve cover off and see what's going on with the top end of that engine. Is there coolant in the oil? The spark plugs are probably soaked as well. Pull them and see.

I'm not certain that the coolant in the throttle body heater circuit can get inside the throttle body itself. It can definitely leak externally if the gasket is bad. Thus, if my theory is correct - coolant INSIDE the engine it likely caused by a bad head gasket or a cracked head.

The engine on my 325is was hydrolocked from coolant getting into the top end of the engine from a cracked cylinder head, courtesy of an older style head bolt deciding to lose its head and get itself jammed under the camshaft. I hope your issue is less severe.