Hi.

 

I have a 2008 tdci 1.6.

 

The thermostat readings show it will not go above 81 C.

 

Is that normal?

Yeah that's about right.  The stat should open at 83c but I wouldn't worry about 2c difference.

These are very thermally efficient.  So unless it's a really hot day and you're thrashing the nuts off it, you won't get the coolant temp to hit 90c.

Really?.

 

I was told by a mechanic it should go higher then that and the thermostat needed replacing..?

 

Can I point you here as this is my actual car...

 

I was also getting a p2458-21 which he said could be caused by the short journeys although I had not long come back from a 200 mile journey. He then said it could be caused by the thermostat being faulty.

 

 

8 minutes ago, aj2703 said:

Really?

 

Yes, really.

On 4/16/2023 at 5:06 PM, aj2703 said:

I was told by a mechanic it should go higher then that and the thermostat needed replacing..?

I worry about these 'mechanics' and their grannies  🤣

I have a Focus 2.0 diesel mk4. It has to be a very warm day and on a good long run before the temp gauge gets past 70^oC

Diesel engines do not get as hot as there petrol equivalents, and modern diesel engines take forever to get warm. Hence the introduction of electric auxiliary heaters for the cabin, so you don't freeze while waiting for a bit of heat from the engine. 

Well the fan did come on when doing short journeys. I drive less than 2 miles to work at 7am and it came on. After it being replaced it does not..... 

 

He was measuring the temps also while I was driving and it never went past 80 / 85.

4 minutes ago, aj2703 said:

He was measuring the temps also while I was driving and it never went past 80 / 85.

....and what temperature would you and your mechanic like it to reach ?

I wouldn't know but he mentioned the 90 mark....

 

Oh dear 🙄

The fan was on before because of the DPF trying to regenerate.  Nothing to do with the thermostat.

55 minutes ago, TomsFocus said:

The fan was on before because of the DPF trying to regenerate.  Nothing to do with the thermostat.

I am sorry I dont understand. 

Doesnt the car have to reach a certain temp so it can regenerate?. 

If the fan is coming on without the car even doing 2 miles in the morning, why would it even try to regenerate

12 hours ago, aj2703 said:

I am sorry I dont understand. 

Doesnt the car have to reach a certain temp so it can regenerate?. 

If the fan is coming on without the car even doing 2 miles in the morning, why would it even try to regenerate

That's certainly what the internet says...  But having owned one of these for over 3 years myself, with no end of DPF issues, and doing a lot of my own testing, the engine doesn't have to be very warm at all before it'll attempt a regen. 

My Golf is even worse for that, will literally trigger a regen within 30 seconds of leaving my car park!

DPF regen produces a huge amount of engine bay heat, the high speed engine fan always runs constantly during DPF regen.

Take the advice given above. If it’s running above 80c I really wouldn’t worry.