2.0TDI 140 Stuck Thermostat

[mxgaza33]

Last few weeks I've noticed my 11 plate 2.0 TDI taking a long time to heat up, that combined with the sub zero temperatures recently and the temperature gauge has been dropping down whilst driving.

I ran a log using VCDS on the way to work and the temperature fluctuates between around 65-80 degrees, having the heating on also results in the temperature dropping so looks like the thermostat is stuck open.

I can see the thermostat in front on the engine but it looks like it could be tricky to get access too. Has anyone managed to change it themselves or is it a garage job?

[xjay1337]

It's a right pain in the ass.

Also make sure that you buy a replacement gasket/seal as this is NOT included with the Thermostat itself.

[mxgaza33]

I've seen a few webpages saying that the oil filter housing, alternator, oil lines and a few other bits need to come off but not 100% sure it that's for the same engine. Is this the case and that's why it's such a pain?

On the hand I got quoted £211 to have it done with genuine parts, if it's as time consuming as it sounds that doesn't seem too bad!

[Deagol]

Last few weeks I've noticed my 11 plate 2.0 TDI taking a long time to heat up, that combined with the sub zero temperatures recently and the temperature gauge has been dropping down whilst driving.

I ran a log using VCDS on the way to work and the temperature fluctuates between around 65-80 degrees, having the heating on also results in the temperature dropping so looks like the thermostat is stuck open.

I can see the thermostat in front on the engine but it looks like it could be tricky to get access too. Has anyone managed to change it themselves or is it a garage job?

My 170TDi has taken longer to warm up this time of year - that much metal in a diesel lump will take a while to get to normal temperature.

With the car cabin heater, mine also "drops" temperature on the dashboard temperature dial if I let it get to "normal" and then turn the heater on. It is as if a batch of "cold" heater fluid in the circuit gets released into the main volume of radiator coolant which reduces the overall temperature for while, until driving gets the average back to where it should be.

Either this is normal behaviour for the time of year, or my thermostat is in trouble too !
This is just me sharing my experience, not stating a problem or a solution, so I'd be interested to hear what happens next with your car.

D

[Steve0]

This is also the first winter with my 170TDi and I do have the same behaviour's as above.

[mxgaza33]

I've had the car for a few years now and until now have never seen the coolant temperature gauge drop below 90 whilst driving, that was the main reason for me suspecting something was wrong.

Putting the heater on does drop the temperature however where it seems to differ from yours is unless the car is under some load (accelerating, on a hill etc) it won't go back up to 90. There is some roads works on my journey to work which means I end up crawling along in traffic for 10 minutes or so, and if the heater is on the temperature gauge will continue to drop down as low as 65-70.

With VCDS plugged in even though the gauge reads 90 it actually fluctuates up and down quite a bit, around 75-85 in my case unless idling or coasting where it can drop lower as I mentioned before.

Do any of you guys happen to know what your oil temp normally sits at? At the moment it's barely reaching 85-88 after my 30-35 minute drive to work.

[mxgaza33]

This is one of the logs I took, 38 minute journey with the outside temperature at about 3-4 degrees. Blue line is the radiator outlet temp incase your wondering why its so low!

[Roy_01]

In which measuring block you are finding the radiator temperature?
Haven't seen it before.

[mxgaza33]

I was using the Advanced Measuring Values screen, then just search for coolant. Should be "Coolant temperature at radiator outlet".

[Roy_01]

Thanks, i don't have it

[xjay1337]

Do any of you guys happen to know what your oil temp normally sits at? At the moment it's barely reaching 85-88 after my 30-35 minute drive to work.

It should get up to around 95 .

Your thermostat is gone. As I said replace it with a new genuine one. If you can't be bothered to do the job yourself £210 all in with genuine parts isn't the worst quote in the world.
The thermostat was around £40+vat, seal was about £8+ . Couple of hours labour .

[mxgaza33]

Just a quick update.

Had the thermostat replaced for £180 including genuine parts. Coolant temperature now gets up to 90 and is much more stable instead of fluctuating between 70-85 depending on driving conditions, oil temp is good now too. Cars got 45k on it at the moment so will look out the problem again at 90k

Problem solved!

[chemitaper]

Just a quick update.

Had the thermostat replaced for £180 including genuine parts. Coolant temperature now gets up to 90 and is much more stable instead of fluctuating between 70-85 depending on driving conditions, oil temp is good now too. Cars got 45k on it at the moment so will look out the problem again at 90k

Problem solved!

don't worry about it so soon, mine is 216k and just this winter is starting to have the same behaviour as yours for the first time... i'll have to replace it next 1-2 weeks...

[Sannasully]

Hi sorry to jump on this thread I don't know how to start my own
I'm having the same trouble. My car is stripped. The car shop have sold my the thermostat on its own with a gasket. I don't believe there is anyway of splitting the housing? Is this correct ?