Overheating in the cold weather !

[tpk241]

Hi All,

Been fighting with a overheating problem for a while now ... Thought i rectified it by clearing an airlock in the coolant system but it seems to have come back now with this cold weather (which baffles me)

I have done the Thermostat, Waterpump, radiator with a know good one. Cleared airlock, checked coolant .. but it still overheats.

The thing is when it overheats the temp gauge goes up to just under the red block, then all of a sudden drops to just below mid again rapidly (which is what happened when i had an airlock) .. Another symptom is no heat from the heater system, gets warmish at best.

This all happened after a day of not starting in the big freeze. It starts fine now and has no coolant leaks or anything. But i wonder if something froze in the system and then trying to start created another airlock ?

Any ideas would be great

Thanks in advance

Stu

[Dave 2000]

Hi All,

Been fighting with a overheating problem for a while now ... Thought i rectified it by clearing an airlock in the coolant system but it seems to have come back now with this cold weather (which baffles me)

I have done the Thermostat, Waterpump, radiator with a know good one. Cleared airlock, checked coolant .. but it still overheats.

The thing is when it overheats the temp gauge goes up to just under the red block, then all of a sudden drops to just below mid again rapidly (which is what happened when i had an airlock) .. Another symptom is no heat from the heater system, gets warmish at best.

This all happened after a day of not starting in the big freeze. It starts fine now and has no coolant leaks or anything. But i wonder if something froze in the system and then trying to start created another airlock ?

Any ideas would be great

Thanks in advance

Stu

This is a classic start of head gasket failure symptom. The gasket starts to leak compression into the cooling system very very slowly, the air rises to the highgest point which is normaly the header tank where it is seperated from the water however, some bubbles make there way to the heater which results in an air lock. The air lock gets bigger and bigger untill the water pump is having trouble moving the water around to cool the engine. Assuming you have check the usual stuff i.e. water pump, thermostat, collapsed hose, blocked rad, faulty viscous unit ect.

regards

Dave

[cipx2]

The thing is when it overheats the temp gauge goes up to just under the red block,

When the needle goes past the mid position and gets near or in the red zone it tells you to "check you wallet, the engine is already f..cked" - namely the head gasket and possibly cyl head, pistons etc, depending on circumstances.

It's been said numerous times on this forum: the temp indicator is useless, fit a proper digital temp sensor with alarm if you care about your engine.

Once overheated and with the symptoms it has, head gasket is the main suspect (cyl head should be checked as well).

[jmattley]

I had a similar problem with my 200 not long ago. It was loosing water on a daily basis, obviously affecting the cooling and causing it to get to 3/4 all the time on temp gauge. Baffled me for a while as I couldn't find a leak anywhere and I was ready to change the head gasket until I found the tiniest little leak in the top heater hose at the back of the engine. Changed that and it's fine. Don't rule that out first. If it is that it could save you a lot of money!!

What's your oil looking like? Should be black, if its getting light brown or white (which is bad!!) it's water getting in through a dying head gasket and should be done straight away.

Also with air locks, have you bled the system properly?