OVERHEATING, PLEASE HELP!

I need some help please.

I have a CGA3 (coilpack 1.4) paired with a CG10 gearbox, clutch and flywheel.

It was running fine on the CG10 ECU for around 3 days. Then I left the car alone for a month and then came back. I did one journey and then the next day, I checked the coolant level and the expansion tank was completely empty.

I topped it to max, which only took about 200ml which I found very weird.

I continued to drive it for the next 2 days, temp gauge all fine. Yesterday I swapped the 1.4 ECU into it.

Now today, I drove it a little bit hard and then heard a boiling sound underneath the hood. I opened bonnet to see the coolant was right at the top of the expansion tank and boiling violently. Temp gauge was still reading fine!

Why is this happening? I recently got a drive belt changed, could this have anything to do with it or is it the ECU? Or the fact the performance of the car now outmatches the cooling system? Could it be the water pump or I drove it too hard?

After letting the car cool down, I have checked it again and the expansion tank is completely empty again! but no coolant had leaked out anywhere.

Please help me people.
 
wait until it cools and then open the radiator cap and see if you can see fluid

Make sure you have the correct amount of fluid and bleed the air out of the system, then see if gentle driving creates the same issue or not. If it does overheat then there's probably some issue with something that's been changed.

If gentle driving doesn't overheat it then but hard driving does it could be that you need to upgrade the cooling system to match up with the other mods for hard driving.
 
wait until it cools and then open the radiator cap and see if you can see fluid

Make sure you have the correct amount of fluid and bleed the air out of the system, then see if gentle driving creates the same issue or not. If it does overheat then there's probably some issue with something that's been changed.

If gentle driving doesn't overheat it then but hard driving does it could be that you need to upgrade the cooling system to match up with the other mods for hard driving.

Okay will check level in radiator cap and bleed air out.

Forgive me for being simple but I checked the coolant bottle last night when the engine had cooled completely, and the coolant bottle was completely empty. Does this not just indicate there isn't enough coolant in the system, hence the engine overheats?

Appreciate the help.
 
I opened the rad cap and could clearly hear air hissing out of it, but then no further bubbles or gurgles of the coolant. Thought this would have solved it.

But then drove the car for about 10 min with smooth driving, temp gauge was completely fine. It went to the correct level around 8 min into driving which is about right. When I got home to check coolant level in the expansion tank, its still the same so no leak but I could clearly see a little bit of steam coming off from the rad fan area, so its clear it is still overheating.

Going to wait for it to cool and then take it to mech as I don't know what to do next.

Blown head gasket/water pump/radiator?
 
wait until it cools and then open the radiator cap and see if you can see fluid

Make sure you have the correct amount of fluid and bleed the air out of the system, then see if gentle driving creates the same issue or not. If it does overheat then there's probably some issue with something that's been changed.

If gentle driving doesn't overheat it then but hard driving does it could be that you need to upgrade the cooling system to match up with the other mods for hard driving.

I opened the radiator cap and could clearly hear air hissing out of it, but then no further bubbles or gurgles of the coolant. Thought this would have solved it.

But then drove the car for about 10 min with smooth driving, temp gauge was completely fine. It went to the correct level around 8 min into driving which is about right. When I got home to check coolant level in the expansion tank, its still the same so no leak (so I thought all was well) but then I could clearly see a little bit of steam coming off from around the radiator fan area, so its clear it is still overheating.

Going to wait for it to cool and then take it to mech as I don't know what to do next.

Blown head gasket/water pump/radiator?
 
What rad has it got (post 2001like to leak)
Heater put out hot air
And when bleeding it the engine should be cold and running to get any air out

Sent from my moto g(6) using Micra Sports Club mobile app

Yes it’s a 2002 with the original radiator, which was lightly damaged in an accident 3 years ago but never gave me any trouble whatsoever before.

And yes the heaters were extra hot.

My main fear was blown head gasket but oil isn’t milky, there doesn’t seem to be any coolant leaks around the exhaust manifold, and performance is normal, so hopefully this is enough to say it’s not the head gasket.

The engine itself is only 40,000 miles so very young yet.
 
Went to mechanic and he said its very likely to be that the thermostat is stuck and faulty - this makes sense because even when the coolant was boiling and the car was steaming, the temp gauge was still reading just a little below halfway.

The coolant pipes were getting squashed as the car heats up, meaning coolant isn't circulating properly.

I'm away for 6 weeks now starting next week so will get a new thermostat fitted when I get back.
 
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Okay will check level in radiator cap and bleed air out.

Forgive me for being simple but I checked the coolant bottle last night when the engine had cooled completely, and the coolant bottle was completely empty. Does this not just indicate there isn't enough coolant in the system, hence the engine overheats?

Appreciate the help.
See I thought this too, it would make sense because of gravity it should drip down but for some reason it doesn't. You can have the expansion tank on maximum and the radiator half empty

Thermostat issue sounds like it's probable
 
See I thought this too, it would make sense because of gravity it should drip down but for some reason it doesn't. You can have the expansion tank on maximum and the radiator half empty

Thermostat issue sounds like it's probable

Before buying a thermostat, I’m going to do a coolant bleed today. I just want to remove all coolant from tank and radiator, remove all air, and then start over.

If this doesn’t solve it, new thermostat will be next.
 
Have bought a thermostat, will put it in along with fresh coolant in 6 weeks time, hopefully that will do the trick.

Thanks to everyone for the help, much appreciated.
 
I need some help please.

I have a CGA3 (coilpack 1.4) paired with a CG10 gearbox, clutch and flywheel.

It was running fine on the CG10 ECU for around 3 days. Then I left the car alone for a month and then came back. I did one journey and then the next day, I checked the coolant level and the expansion tank was completely empty.

I topped it to max, which only took about 200ml which I found very weird.

I continued to drive it for the next 2 days, temp gauge all fine. Yesterday I swapped the 1.4 ECU into it.

Now today, I drove it a little bit hard and then heard a boiling sound underneath the hood. I opened bonnet to see the coolant was right at the top of the expansion tank and boiling violently. Temp gauge was still reading fine!

Why is this happening? I recently got a drive belt changed, could this have anything to do with it or is it the ECU? Or the fact the performance of the car now outmatches the cooling system? Could it be the water pump or I drove it too hard?

After letting the car cool down, I have checked it again and the expansion tank is completely empty again! but no coolant had leaked out anywhere.

Please help me people.
HAVE you checked the thermostat just to see if you get hot air coming though the heater (forget the hot weather) if not change the thermostat as this is what happened to my first k11 as it was overheating and finally bellow the head gasket. Yours Peter0003
 
HAVE you checked the thermostat just to see if you get hot air coming though the heater (forget the hot weather) if not change the thermostat as this is what happened to my first k11 as it was overheating and finally bellow the head gasket. Yours Peter0003

Thanks for your input. Yes I am sure it is the thermostat as well now. The heaters will only blow out hot air, and no cold air even when on the coldest setting.

Will change the thermostat and do a full coolant drain when I'm back in 6 weeks.

Thanks.
 
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