Coolant Consumption for a TDI

[Tdijimmy]

Noticed a few days ago that when my diesel polo is cold and hasn't been used for a few hours/overnight etc, the coolant level sits about 2-3cm below the min level in the expansion tank.

The only puddle i've ever noticed under my car is in summer from the A/C unit. What i'm wondering is it normal for a polo to consume minor amounts of coolant over the course of running? The car has done about 43,800km since new last year and has always been serviced very close to the scheduled intervals.

Any help would be great!

[wai]

You can get a minor amount lost through evaporation, and it does expand and contract with changes on temperature, but coolant consumption is a no-no. The level should remain relatively consistent under the same conditions.

The best way is to get someone to pressure test the system and see if it is holding pressure. If it is not, then it is a case of elimination.

First, check for any obvious leaks. If there are not, then it is getting out into the exhaust, or leaking on to the exhaist and so leaving no trace.

[Transporter]

It's closed cooling system, so no coolant loses to evaporation. Only the cars that have the expansion bottle open to air may need a very minor top up over the years.

[alexaescht]

My TDI's coolant was a bit low just before last service when it was topped up. Similar symptoms to yours – ~2-3 cm below minimum level and only when cold. Only difference is this car had done 90,000 km when this was noticed.

[Transporter]

No harm done mate. As long as the air doesn't get mixed with the fluid, it's all good.

[alexaescht]

Good to know. Glad it's nothing to worry about

[Diesel_vert]

With the car level, the coolant level should be between the MIN and MAX when cold. If it is below the MIN level, it should be topped up with coolant (of the same product) or distilled water.

Due to expansion, the coolant level may exceed the MAX level when hot, but that is normal operation.

If the coolant level does not drop after topping up, then I would not worry about it.

[Transporter]

Yeap, that's why there are the Min and Max marks on the reservoir.