Collected my new car yesterday and went straight to the fuel station, as it was running on fumes.  I fuelled up for the 100 mile journey home and set off.  After a few miles I was on a dual carriageway, so I set cruise control at just over 60.  The next thing I knew, the temperature gauge was heading north of 90 and I watched as it made its way up to 110.  I pulled into a lay-by and left the engine running, and the gauge went down to 90 again.

 

At this point, I was wondering if I should phone the garage or not.  Anyway, I set off again and the gauge stayed firmly on 90 for the rest of the journey.

 

This morning, I ran the VAG-DPF app to see what the state of the DPF was.  It said that the last regen was 143km ago, which is about 90 miles.

 

So, the question (finally) - does the engine coolant temperature increase when a regen is happening?  It looks like the increase in temperature reading was about the same time as the regen was happening.

No, the gauge should stay at 90 also during a regen.

Report the Issue to the garage tomorrow.  Just incase you need to have them do work under warranty. Likely you will. 

When was the cam belt and water pump changed according to any history?

Edited 2 February, 20251 yr by Ootohere

Assuming its not "new" new as you've posted in the Mk3 forum. What mileage is it at & when was it built?

 

This issue sounds exactly like the common TDi water pump problem.

When the problem first begins, the temperature will increase towards the red (but not reach red & does not trigger any limphome).

If you continue for 30s-1minute the temperature will decrease again.

 

The problem is during warmup, the water pump has a electronically controlled sleave to warmup the engine quickly & then open to allow water from the radiator/tank to flow through the system once its at temperature.

The sleeve is "sticky" on the old parts (due to different temperature/expansion properties of the materials) & can take time to "pop" open once the temperature of the materials matches.

 

I used to "dip" the clutch and wait a few seconds until the temperature needle started to decrease again.

It will do it once per driving cycle & will be fine for the rest of the journey.

 

I would call the garage immediately to inform them & ask when/if the water pump (and timing belt) was changed.

In the past Skoda/VAG was offering 50-60% of the cost of this because it was a common problem.

As your car is new it should come with at least a 1 year warranty so I would be insisting that the water pump (and timing belt) are replaced free of charge.

 

The timing belt is not normally part of the water pump change, however, it must be removed to change the pump so you might as well change it at the same time.

If the garage says no, I would offer to pay for a new part as it will save you several hundred pounds in the future to change it when its due.

1 hour ago, Gabbo said:

Assuming its not "new" new as you've posted in the Mk3 forum. What mileage is it at & when was it built?

 

This issue sounds exactly like the common TDi water pump problem.

When the problem first begins, the temperature will increase towards the red (but not reach red & does not trigger any limphome).

If you continue for 30s-1minute the temperature will decrease again.

 

The problem is during warmup, the water pump has a electronically controlled sleave to warmup the engine quickly & then open to allow water from the radiator/tank to flow through the system once its at temperature.

The sleeve is "sticky" on the old parts (due to different temperature/expansion properties of the materials) & can take time to "pop" open once the temperature of the materials matches.

 

I used to "dip" the clutch and wait a few seconds until the temperature needle started to decrease again.

It will do it once per driving cycle & will be fine for the rest of the journey.

 

I would call the garage immediately to inform them & ask when/if the water pump (and timing belt) was changed.

In the past Skoda/VAG was offering 50-60% of the cost of this because it was a common problem.

As your car is new it should come with at least a 1 year warranty so I would be insisting that the water pump (and timing belt) are replaced free of charge.

 

The timing belt is not normally part of the water pump change, however, it must be removed to change the pump so you might as well change it at the same time.

If the garage says no, I would offer to pay for a new part as it will save you several hundred pounds in the future to change it when its due.

Thanks for that, very interesting. 
 

The car is 2015 with 55k miles.

It's around the right age & mileage (mine was 2014) and my water pump went around 100k km just over 3 years old

 

Given your mileage it's unlikely the timing belt or water pump has been changed. 

Iirc it's 100k miles recommended interval (I'm sure someone else can confirm).

 

There's a big thread here concerning this problem. 

 

 

Gabbo 

 

I've just been out for a road test, to see if I could replicate the problem, using OBDeleven live data to see what the temperature was.

 

It took about five miles for the gauge to reach 90°, although the live data reading was only 78° at that point.

All subsequent temperatures are from live data, as the gauge never moved off 90°.

 

Over the next three or four miles, the temperature went up gradually until it reached 106°.  It then dropped reasonably quickly to 90/91, then for the rest of the journey it cycled between 92 and 97°, presumably as the thermostat opened and closed.

 

Not very conclusive, as I don't know at what temperature the water pump sleeve does its thing.

 

It would be interesting to know what the actual temperature was on Saturday, when the gauge reached 110°.

Two get two warnings with the failing water pump.  You've just had the first one.  Check the water pump and see if its leaking or wheeping.

You will get one more fluation usually before the pump grenades itself and the car overheats.  Time for a new waterpump (and probably a cambelt if you can)

The temperature dial is not linear or accurate, between 70-110 it will just stay at 90°. 

 

You can add Coolant Temperature in the maxidot display which will give you a more representative value.

 

When you have the beginnings of the water pump problem, it will occur shortly after starting the engine after the when the temperature gauge reaches 90. 

 

You will suddenly see the temperature gauge moving towards the red & you will get a warning "coolant temperature high" in the maxi dot.

In my case it was just a warning and before the temperature exceeded 130deg and entered the red, the water pump would pop open and the warning would disappear.

 

Reading the DTCs will give you a water pump position control error.

 

The water pump sleeve operates once in a engine cycle so as long as the engine stays hot, it won't open or stick again.

 

For me it only happened when I started from cold, drove a few Kms & stopped at the nursery for 10 minutes to drop off the kids.

When I returned to the car, drove into the highway then I would get sometimes the temperature warning. 

If I started from cold and drove directly on the highway I didn't have the problems. 

 

There was no coolant leaking or coolant loss it was purely a mechanical error with the sleeve.

 

I drove my car like this for ~4 months because of part availablity and the error occurred once or twice a month but getting slightly more often the longer it went on.

 

I've driven 150k km with the new part without any issues.

25 minutes ago, Gabbo said:

 

Reading the DTCs will give you a water pump position control error.

 

 

 

I ran a scan yesterday, but there were no water pump related faults showing.

On 03/02/2025 at 14:04, Gabbo said:

You can add Coolant Temperature in the maxidot display which will give you a more representative value.

I don't seem to be able to add coolant temperature as an option.

I have now had the water pump replaced under warranty.

The warranty covered the cost of the pump and labour. I paid the extra for a timing belt kit.

This was a good deal & should give you another 100k worth of Worry free motoring.

Great result.

Assuming you had a 1 year warranty with the purchase?

On 03/02/2025 at 12:20, daveo138 said:

Over the next three or four miles, the temperature went up gradually until it reached 106°.  It then dropped reasonably quickly to 90/91, then for the rest of the journey it cycled between 92 and 97°, presumably as the thermostat opened and closed.

 

Not very conclusive, as I don't know at what temperature the water pump sleeve does its thing.

Absolutely normal behavior for a wax capsule thermostat.

The water pump sleeve does its thing in the early stage of the warm up, I doubt that you would see anything in live data other than feeling heat coming from the heater without a corresponding increase in live data temperature because the coolant is running in a direct circuit through the heater.

53 minutes ago, Gabbo said:

This was a good deal & should give you another 100k worth of Worry free motoring.

Great result.

Assuming you had a 1 year warranty with the purchase?

There was a 3-month warranty from the dealer, but I purchased a 12-month warranty for £260, which was well worth it, plus I’ve got 11-months cover left in case anything else goes wrong.