UK-POLOS.NET - THE VW Polo Forum

Dear all,
. Hope you are doing fine. I would like to seek an advise. I am driving a volkswagen polo 1.6 year made 2015.

Recently i sent my car to one of the workshop nearby to change some parts for my car as listed below

1. Cylinder head
2. Cylinder head cover
3. Head gasket
4. Valve seal
5. Plug seal
6. Timing cover gasket
7. Engine oil

After changed all the parts below, the workshop claims my car engine temperature rises to 120 and they advised me to change thermostat. I asked them to change the thermostat and then they said the temperature is now 105. They suggested me to change the water pump and i did so changing the water pump. My car temperature still shows 105.

When i start the car, initially it will rise to 90. After about 7 minute, the temperature goes to 100 or something 105. When i revved the engine RPM to 1500 or 2000, the temperature drops back to 90 and when I stopped raving it goes to 100 back.

When I drive at constant speed on highway, the temperature will be 90. When i stuck at traffic it will rise to 105

From your point of view, what do u think the problem might be because i am worried the workshop ask me to do unnecessary things which the cost will be high.

I also realised that my car heater not function after the cylinder head change. Please assist me sir on this. Thank you

Hi,

it does sound a lot like there is air trapped somewhere in the cooling system, I don't know anything about your 1.6 engine, but I do know that the old 1.4 16V Petrol engines could be difficult to get rid of trapped air after the cooling system had been opened up or emptied. For that 1.4 16V engine, the solution was to remove the engine coolant temperature sensor and watch for air and coolant escaping while filling the cooling system, only when it was only coolant free from air bubbles that was escaping from the hole where the engine coolant temperature fits into, that it gets fitted back in place while continuing to pour coolant into the coolant reservoir.

I removed the coolant from my older daughter's 2009 SEAT Ibiza SC 1.4 16V - same/similar car to VW Polo, after refilling it, I went for a maybe 10 miles run to try to get the car to purge all the remaining air out of the coolant system - that did not happen, the heater was only warm for a short period! After that, I dug deep in the VW Group forums and found what turned out to be a correct way to fix that, ie by removing the engine coolant temperature sensor and letting the system get rid of the trapped air while adding in more coolant.

Also make sure that your cooling fan or fans, if there are 2, can still be run at LOW and HIGH speeds, it is mainly the LOW speed resistor that fails and when that does, the engine temperature rises to the point where the LOW cooling fan should switch on - it doesn't so the engine temperature rises higher than it should and eventually the cooling fan gets run at the HIGH speed, this, if there is no trapped air in the coolant system and everything else works, will bring the engine temperature back down and then that cooling fan switches off, and the engine temperature starts to get too high again and the sequence repeats. If/when the cooling speed LOW speed is still working okay, the rising engine temperature is caught and cooled back down before it rises too high, and that LOW speed running fan will just cycle ON/OFF as required.

Good Luck as you seem to have spent a lot of money already - also, make sure that the coolant radiator is clear of any debris or blockages.