Overheated now cranks but will not start

DRICE2

MEMBER
2006 CADILLAC CTS
2.8L
6 CYL
2WD
AUTOMATIC
215,000 MILES

First of all, the ECM has been bad for a year, but it has driven fine, gauges didn't work, but drove fine. Was driving about fifteen miles and the A/C stopped blowing cold and the check engine light came on. I stopped, got gas and drove about ten more miles with no cold A/C. Pulled over, checked coolant and it was low, added coolant and let it cool down for about thirty minutes. When I tried to start it, it cranked more than usual but finally started. I made it about ten miles and steam/smoke started rolling out from under the hood. As I pull off the road it quit running. Let it cool and now it won't start. Cranks and acts like it wants to start. But doesn't. When cranking it blows back through the coolant reservoir. So I assume blown head gasket, but it should still start right?

3 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

Not necessarily. An engine needs three things to start and if all three of these things are present, it has no choice but to start.1) Fuel. 2) Spark (delivered at the proper time). 3) Compression. It's the latter of the three that would concern me on your vehicle because when an engine goes through an overheating event, like your's did, the two halves of your engine (the block which is iron and the cylinder head which is aluminum) cool at different rates. The end result usually is warping of the cylinder head which in turn causes the head gasket to fail. So, it probably isn't just the head gasket, it's probably the cylinder head that has failed. I have included a few links below for you to go to:

https://www.2carpros.com/articles/how-to-test-engine-compression
https://www.2carpros.com/articles/head-gasket-blown-test
https://www.2carpros.com/articles/symptoms-of-an-overheating-engine

Please go through these guides and get back to with what you are able to find out. We will have some more guidance should you require it then.

Thanks,
Alex
2CarPros