Can a stuck thermostat (closed) lead to a blown HG?

[booster]

I am not a mechanic and my car has a suspected blown headgasket. I drove it last week and after 100 miles it broke down and the RAC man said the thermostat was jammed closed. We replaced it and carried on but kept overheating and finally gave up the ghost after about another 200 miles. Do you think the jammed thermostat could have caused the HG to blow in the first place?

[BigMacDaddy]

Quite easily - if the thermostat doesn't open the coolant in the engine won't flow into the radiator, so doesn't then actually cool the engine!

[HustleRussell]

It has to be up there as one of the most common causes...

[Simon says]

In future you will save yourself a lot of grief if you don't drive the car overheating if your fortunate it may just be the headgasket that's blown modern cars are far less tolerant to this kind of behavior and can often suffer further engine damage

[stevieturbo]

booster said:

I am not a mechanic and my car has a suspected blown headgasket. I drove it last week and after 100 miles it broke down and the RAC man said the thermostat was jammed closed. We replaced it and carried on but kept overheating and finally gave up the ghost after about another 200 miles. Do you think the jammed thermostat could have caused the HG to blow in the first place?

So you drove it on until it stopped with the temperature gauge reading how high ?

[booster]

stevieturbo said:

So you drove it on until it stopped with the temperature gauge reading how high ?

We continued on as the RAC man replaced the thermostat. Everything seemed normal and no reason not to continue. The 2nd time it overheated we took it to a garage who suspected an airlock and bled the system. Again no problems for about another 100 miles. The third time was when when was when we called it a day. As soon as the temp gauge started to rise we stopped the car everytime.

[Simon says]

booster said:

stevieturbo said:

So you drove it on until it stopped with the temperature gauge reading how high ?

We continued on as the RAC man replaced the thermostat. Everything seemed normal and no reason not to continue. The 2nd time it overheated we took it to a garage who suspected an airlock and bled the system. Again no problems for about another 100 miles. The third time was when when was when we called it a day. As soon as the temp gauge started to rise we stopped the car everytime.

Sensible fella what car and model is it?

[hman]

A friends van blew its engine like this, the coolant temp sensor was on the rad, the coolant was trapped going around the block due to stuck shut thermostat so he only knew about it when it suddenly blew out the head gasket and warped the head - until then the temp had been cold as the sensor was not getting any hot water near it...

[Limpet]

hman said:

A friends van blew its engine like this, the coolant temp sensor was on the rad, the coolant was trapped going around the block due to stuck shut thermostat so he only knew about it when it suddenly blew out the head gasket and warped the head - until then the temp had been cold as the sensor was not getting any hot water near it...

Something similar used to happen on the old Vauxhall OHC engines. The temperature sender was mounted in the thermostat housing at one of the highest points in the cooling system (it doubled as a bleed screw, IIRC). If the coolant level dropped below a certain point, the sender was left measuring air rather than coolant. The gauge would show normal-ish as the engine cooked itself.

[Simon says]

Limpet said:

hman said:

A friends van blew its engine like this, the coolant temp sensor was on the rad, the coolant was trapped going around the block due to stuck shut thermostat so he only knew about it when it suddenly blew out the head gasket and warped the head - until then the temp had been cold as the sensor was not getting any hot water near it...

Something similar used to happen on the old Vauxhall OHC engines. The temperature sender was mounted in the thermostat housing at one of the highest points in the cooling system (it doubled as a bleed screw, IIRC). If the coolant level dropped below a certain point, the sender was left measuring air rather than coolant. The gauge would show normal-ish as the engine cooked itself.

That's Rover K series problem too

[booster]

The car is a Toyota MR2 Mk1b. It has done just over 1000 miles since its engine rebuild too However, that was over 4 years ago - the car has been in a specialist car storage unit since then. Just took it out for a jolly and hey ho - the bloody thing breaks down!