Causes of a blown head gasket

[Dan]

Hello world

I just saw a 2007 Chevy Cobalt LS that was listed on Craigslist for 500 dollars.
The lady said a few weeks ago a mobile mechanic changed the timing chain, then about two weeks later she was driving, the car juttered before making a loud noise and eventually dying.
Towed it home and called the guy who replaced the timing chain.

He supposedly started the car and it was pouring white smoke from the tailpipe and called the head gasket.

She does not think that the car overheated.

The internet has two different thoughts on this car. One is that the head gasket is 100% blown off you’re burning coolant. And the other is that the intake manifold can crack and do the same thing.

I looked in the oil and didn’t see anything that would suggest coolant mixing in it, and the car has no battery at all so I couldn’t run it.

I’m not ruling out that the timing chain job may have been botched either. If the engines destroyed then I don’t want the car.

What (if anything) other than overheating can blow a head gasket?

Topic

[Richard Kirshy]

Overheating
Pre-ignition or detonation
Poor gasket
Over-revving a cold engine

[Mathieu]

A bad timing won’t overheat an engine, It’s will make stop in the worst case scenario and run rough in the est scenario.
Air in the coolant engine system can lead to over pressure in the system if the radiator cap spring is defective. The same thing can happen if the car have an coolant overflow to balance the coolant and the pipe from the radiator to the overflow tank is locked. And overheating engine block will crush the head gasket by the physic of metal expansion. Then, your gasket is not longer useful and need to be replaced. An over heating engine can also happens when people have a 6000 RPM while not moving for 2 to 5 minutes.

When you change coolant, you need to bleed the air from the engine block and the cooling system to avoid overheat and cold air in the cabin heater.

[Author]

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