Head gasket Q

[gofish]

Just wondering what (if any) are the signs of a HG on it's way out. Cheers.

[loanrangie]

Depending on where its failing, bubbles in the expansion tank/ rad are usually first signs but usually by then its a forgone conclusion.
Will be dependent on the engine type as well.

[sheerluck]

Just wondering what (if any) are the signs of a HG on it's way out. Cheers.

A head gasket can "go" in a number of ways.

It can go between cylinders, between oil and coolant paths, between coolant paths and cylinders, externally from the cylinder......

So you may get one, many, some or all of the following:

Pressurising of the coolant header tank.
Bubbles in the coolant
Oil in the coolant
"Mayonnaise" under the oil cap
Chuffing out of the head
Oil leaks
Coolant leaks
Coolant disappearing
Power loss

[trev]

besides the above,you may also get the gurgles behind the dash in the heater matrix indicating gas buildup.

Trev.

[3lud13]

A head gasket can "go" in a number of ways.

It can go between cylinders, between oil and coolant paths, between coolant paths and cylinders, externally from the cylinder......

So you may get one, many, some or all of the following:

Pressurising of the coolant header tank.


Do you think that could cause a blowout in a radiator hose maybe?

[sheerluck]

Do you think that could cause a blowout in a radiator hose maybe?

Absolutely. ;)

[1999td5]

So pressurization of the system. Blowing out top radiator hose. then another hose etc. Isn't the radiator cap supposed to prevent over pressurization of the cooling system?

[3lud13]

Absolutely. ;)
Well thats a relief as that is the only reason I can come up with that my hose blew despite its age. Headgasket is on my todo list just saving some more coin to do it.

So pressurization of the system. Blowing out top radiator hose. then another hose etc. Isn't the radiator cap supposed to prevent over pressurization of the cooling system?
Thats what I thought too but I have a brand new cap so I guess it doesnt prevent over pressurization

[sheerluck]

So pressurization of the system. Blowing out top radiator hose. then another hose etc. Isn't the radiator cap supposed to prevent over pressurization of the cooling system?

A healthy petrol engine can compress it's exhaust gases up to about 180psi. If the head gasket is leaking, the compression will be lower than that , but still considerably more than the 16-20psi that most coolant header tank caps will vent at, and can vent at the same speed as the pressure builds up.

That extra pressure will look for a way out, a weak spot in a hose, a hose clip, another gasket.....

[1999td5]

thanks Dave

Put it like that I got it now:D

[Aaron IIA]

A healthy petrol engine can compress it's exhaust gases up to about 180psi.

If your petrol engine is compressing it's exhaust gas to 180psi, it is anything but healthy. I would suspect the exhaust valves are not opening.
Aaron

[sheerluck]

If your petrol engine is compressing it's exhaust gas to 180psi, it is anything but healthy. I would suspect the exhaust valves are not opening.
Aaron

Yeah, I don't know why I put exhaust in there. Just "compress" would be correct.