Engine Overheating

[Fr0dders]

Quite recently during the last couple of hot days, the car has started to intermittently beep an engine temperature warning at me

This quite often occurs for a short ammout of time, shortly after which the engine temperature gauge goes from maximum, back down to zero, and then back to its normal 2 bars. When this happens the extra fan kicks in

I'm unsure if this is an electrical fault, or if the engine is actually overheating. Ive not seen any steam come from the radiator, but i've never checked the radiator / coolant levels. I've always just taken it in at the required service intervals and never given it any more thought other than checking i dont run out of oil.

Is the temperature guage and the thermostat for the fine likely to be the same unit , and is this possibly an electical fault with it ?

Or should i be regularly checking my coolant levels during these hot summer months ?

 

[Fr0dders]

I've never bothered checking the coolant before, i've always just taken it in for servicing at the required interval and thought nothing more of it. I had a look in the handbook for coolant, but it wasnt exactly clear where you put it. It just had diagrams rather than words clearly telling you what symbol meant which fluid.

 

[Fr0dders]

right, checked the coolant level. It is in fact a complete pain to check, and they've devised the most hard to read container you can imagine. But ive managed to establish that allthough its not on the max mark, its certainly well above minimum and probably somewhere nicely inbetween the two.

Interesting thing though, the owners manual says the coolant is to prevent damage due to frost and for preventing rust. Nothing about it being essential for keeping the car cool in the summer.

But anyway, im guessing the only other thing it can be, seen as the temp gauage keeps fluctuating between max and min is an electrical fault with the temp sensor ?

 

[Fr0dders]

i'm not sure whats going on here

The water that runs through the radiator and engine cooling the system surely needs to contain litres and litres of the stuff ? but the clear plastic box marked as "coolant" in the manual is like half a litre at most.

Somebody said that a coolant flush and re-fill can be like 10 litres. So maybe the box marked "coolant" in the manual, is in fact just an antifreeze reservoir or something ?

Told you the manual wasnt clear !

 

[Fr0dders]

The tank is the expansion tank - it is connected to the rest of the system and contains many litres.

right, so the fact i can see its got fluid in, and appears to be somewhere just below the max line means it is in fact full of coolant ?

anyway ive done some researching, and it seems the likely culprit is a faulty coolant temp sensor. Seems quite common.

It fits with the behaviour of the guage as well, i never see it rise to 3 then 4 bars, it just suddenly shoots from 2 bars to full, then back to 2 bars again. When it hits full, the 2nd speed of the fan kicks in and the fan goes into overdrive, the temp sensor then reads normal and the fan goes back to slow speed again.

So the thermostat is fine, but looks to be a faulty temp sensor. Assuming the garage dont try and fob me off with leaking head gaskets and skimming the head etc.. it should be just a £10 + fitting job.