Help needed with 6r cbzb engine 77kw cooling system.

[mesitisg]

So guys my Polo 6r with engine cbzb 77kw is misbehaving.

I have an obdii gauge and also the Carly obdii dongle both monitor the coolant temperature.

After 20 minutes driving with 20⁰c outside the coolant temperature rises to 102⁰c momentarily and then drops to 96⁰c. This cycle continues during the drive.

I have noticed that the rad fan comes on at 102⁰c for a few seconds only at the low speed and the temperature drops to 96⁰c.

The rad fan runs when the AC is on.

Before this begun the car would run steady at 96⁰c according to the obdii gauge.

I had the thermostat replaced yesterday and the problem persists. The water pump was replaced around 5000 miles ago.

When does the rad fan kick on?

Any imput much appreciated.

[ciclo]

It seems like normal behaviour of the cooling system within the appropriate parameters.

[mesitisg]

Thank you for the reply.

I worry that this temperature levels are too high and I believed that the radiator fan would come on at it's low speed at 96c.

[ciclo]

The coolant temperatures at which the fan turns on and off are appropriate, and it is also normal for the fan to run when the A/C is turned on.
The outside temperatures and the power/load required are determining factors 'for the times' in which the fan is working, which is not a cause for concern.
It is certain that the thermostat is working correctly, another thing is that the replaced pump is performing adequately or providing the correct flow.

Install a new pump if you think it is not working properly.
Use original spare parts on this occasion if you did not do so in the previous pump replacement.

[mesitisg]

Thanks for your reply my friend. I will be keeping an eye on the coolant temperature with the OBD2 gauge and if it starts creeping upwards I will change the pump.

[ciclo]

As a precatory measure, you can use your hands/take a look -with the engine cold- to check the vacuum lines or electrical connectors to ensure that the engine control unit or cooling system components are receiving the correct signals. Use a flashlight.

[Le_Combattant]

No worries to have, a +100°C water temps is normal.

[mesitisg]

Thank you for your insights guys.

I tend to overthink things at times

[Le_Combattant]

I had the same "issue" when trouble shooting my engine hesition when cold.
I was thinking about a bad temp sensor.

When I saw 106+ degrees I felt so bad. But after few research, it's perfectly normal.

[Retali]

I had the same "issue" when trouble shooting my engine hesition when cold.
I was thinking about a bad temp sensor.

When I saw 106+ degrees I felt so bad. But after few research, it's perfectly normal.

So what ended up being your problem and solution for the slaggish jerky hesitation ?

[Le_Combattant]

This, carbon on the intake ports:

PXL_20240228_125632473.jpg (2.1 MiB) Viewed 1612 times

[Retali]

This, carbon on the intake ports:

PXL_20240228_125632473.jpg

Thanx! How did you end up cleaning it ?
Soda blasting (or similar) in a workshop ? or did you do anything yourself ?

[Le_Combattant]

This, carbon on the intake ports:

PXL_20240228_125632473.jpg

Thanx! How did you end up cleaning it ?
Soda blasting (or similar) in a workshop ? or did you do anything yourself ?

Ice blasting, company service (250 euros).