Whilst driving yesterday on the motorway on cruise at 70mph for 30 miles, dead calm and 14 degrees with no load with aircon on , I noticed the digital temperature gauge had moved from the normally steady 90d. to 104d.

Then whilst watching it then started fluctuating down to 100.d up then 105d.

This was all at the same speed, once on the drive it suddenly started to drop slowly to 90 again both radiator fans were running for a while (always let it idle for 2-4 mins) after a run.

Checked the radiator expansion bottle and was at the level it has always been about the bottle half way seam, no obvious signs of coolant leaks / odours.

Checked oil level and all looked ok, it was serviced about 200 miles ago.

Any ideas on possible cause.

Thanks

martin

 

Hi, you say 'digital temperature gauge' - is this the Maxi Dot oil temperature reading? 

High Warrior193, car has the digital dashboard, yes it's the oil temp reading. 

Are you talking coolant temp or oil temp?

If the Oil temperature it was doing as oil does, and the coolant system and fans getting the oil back down near the 92*oC that the coolant is at. 

Thanks for your comments everyone, I understand that the engine self regulates it's temperature, as i mentioned this has never been as high or moving up and down so instantly as I saw whilst driving steadily in calm relative conditions.

Whilst towing our caravan with a boot full of luggage in warmer weather the oil temp never rises above 90 degrees, that's what I cannot understand.

Martin 

My oil temperature fluctuates quite a lot during a drive, even at the same speed. Can't remember the highest it's been but would be at least 115 I think - at high speeds, never particularly near the 'red'.

Mine fluctuates but is regularly above 95 - has done since I bought it 3 years ago so adding my assurance to this. 

On 22/10/2024 at 05:10, kentdale said:

Thanks for your comments everyone, I understand that the engine self regulates it's temperature, as i mentioned this has never been as high or moving up and down so instantly as I saw whilst driving steadily in calm relative conditions.

Whilst towing our caravan with a boot full of luggage in warmer weather the oil temp never rises above 90 degrees, that's what I cannot understand.

Martin 

 

Hi,

Are you sure you don't mix oil and coolant temp displays?

Coulant system is designed to keep almost steady at 90°C, whereas the oil temps is rather around 100°C and can fluctuate in a larger range.

 

Coming back to your initial question. I don't see signs of water pump issue at this time. Note: I had to replace mine at 62000km (I'm also a TDI190 4x4 owner).

Hi Bap33, yes I did mix oil temp with coolant temp , spoke to my independent garage who confirmed oil temp can fluctuate and it sounded an ok temp.

Used car today and all fine ,water always 90 degrees and oil about 95 degrees on a 15 mile drive there and back but also about 6 degrees colder day than last drive.

Martin.