Loud bang and the rattle highway speed

Yes, in the radiator.

This is why a blown head gasket is so bad. In the cylinder head during combustion, exhaust is created during the BANG phase.

When the head gasket is breached, some of that exhaust gets blown through the crack or gap where the gasket failed.

On virtually any piston engine there are four possible destinations for this leak:

• an oil passage
• another combustion chamber
• the outside air
• the coolant passages.

That last one is popular. So in many head gasket cases, you get bubbles of freshly-created exhaust in your antifreeze. The water pump will dutifully circulate them, and a few seconds later you have exhaust bubbles in the radiator where a fancy chemical analyzer can positively ID them.

 

I already know this....

I quote: "The service center used a test that checks for exhaust gases at the radiator."
Notice the "AT". Not "in"....

Never had anyone say it banged. 99.9% of the time when a head gasket goes it's slow.
Unless you have a racing engine....

 

Ah, semantics thing. Fair enough, I guess we will have to let the OP clarify.

 

Yes, sniff coolant IN the radiator or expansion tank/filler tank with an exhaust emissions analyser.
It’s better done with the system hot, the analyser will sniff hydrocarbons which, if present is a pretty good indicator of a failed head gasket or other ingress of combustion gases (such as a hairline crack)

 

I guess a lot of us just resolved any semantic ambiguity between 'at' and 'in' by applying what we know about how a service center does that test.

 

It's not a big deal, really. Though some really love to beat a dead horse.

 

I guess (wham!) checking at that bottle would work (pow!) in a 2012 because in the Gen 3 cooling system (thump!) it's not really an overflow tank but a degas bottle and the fluid (smack!) always circulates through it, so it's the same as what's in the (thud!) radiator.

In a Gen 1 or Gen 2 (crunch!) it really is an overflow tank, and I'm not sure checking there would be as effective as in the radiator. (Splurtch! eww.)