Car Overheating - No Coolant Leak?

chaotic_j

Hi,

Just over a week ago half way to work I got a warning on the car dash that my engine was overheating. The car is a 2015 Corsa E 1.4l.

Nowhere to stop so carried on down the hill and it disappeared - rest of journey fine.

Going home same situation.

Checked coolant and was well down in the reservoir, topped up. Did not drive and took to local independent garage 2 days later.

What I thought was a leak dripping underneath - just the air con. They connected to a piece of equipment that pressure tests and no leaks.

They topped up coolant and said car running fine, probably an air lock.

So driving home from work tonight, very hot weather, engine overheat warning 3 times. The first disappearing when I picked up some speed.

Then it's warning me almost constantly. Stopped and popped the bonnet - very hot but no steam? Currently waiting for engine to cool.

Just wondering if anyone could help troubleshoot please?

Thanks in advance!

knightstyle

Thermostat sticking closed?  Remove it temporarily and see if that fixes it but replace it before winter.

molerat

Thermostat stuck ?  Fan not operating ? Water pump not pumping ? But I would assume the garage would have checked these

Reminds me of the "good old days".  Driving crawling through central London mid summer with the heater and blower full blast and all the windows open

chaotic_j

So last week I had the car running idle and checked the fan, it was running and turning off which I think is normal.

Not sure regards thermostat and water pump.

At traffic lights it was overheating again - could hear a sort of low brrrr brrrr brrrr brrrr brrrr brrrr noise which I don't remember hearing before?

chaotic_j

Put heater on full and it's blowing cold?

[Deleted User]

The noise your hearing at the traffic lights is likely the fan motor kicking in and out.

The cold air from the heater is concerning, this may be symptomatic of severe coolant loss.

Did the garage check for cylinder head damage while investigating the coolant loss?

Ectophile

Has anyone checked that the temperature sensor itself (or the wiring to it) isn't faulty?

The_Fat_Controller

Cold air when the heater is on full is a very bad sign.

Have you checked the state of the oil on the dipstick and if there is any white oil/water emulsion under the oil filler cap ?

If you are losing coolant without any obvious leaks then it could be a failed head gasket.

Get back to a mechanic as soon as possible or you may do terminal damage to your engine.

chaotic_j

Ok so I've checked the coolant and there is loads been lost - like a week ago when I last had the overheating. It was well below the header tank level.

They connected the cooling system to a machine that runs under pressure and said no leaks all running fine so topped up.

The oil seems OK, I checked the dipstick and filler cap last week, oil on minimum no white stuff. Checked again just now oil on middle point and no white stuff. As I did read about head gasket and feared the worst!

I don't think they have checked anything else. It said online it isn't normal to lose a lot of coolant that's why I stopped driving it and went to the garage straight away!

[Deleted User]

chaotic_j said:

The oil seems OK, I checked the dipstick and filler cap last week, oil on minimum no white stuff. Checked again just now oil on middle point and no white stuff. As I did read about head gasket and feared the worst!

I don't think they have checked anything else. It said online it isn't normal to lose a lot of coolant that's why I stopped driving it and went to the garage straight away!

You need to have it tested for products of combustion getting into the coolant, its easily done and is a simple chemical test. The garage should have done this as a matter of course if other tests were inconclusive.

Edit: DIY https://www.drheadgasket.co.uk/COMBUSTION-LEAK-TESTER-HEAD-GASKET-TESTER-BLOC-SNIFF-TESTER-COMBUSTION-LEAK-DETECTOR-DR-HEADGASKET-UK

chaotic_j

Thanks for your help I've taken the car into a different garage this morning, hopefully they will find the problem.