FYI - My 2008 V6 TDI sits as steady as a rock on 90 C and does not move, either in mid summer at 40 C or Last week in Canberra at 2 C.... I think 100 C (210F) sounds a little high...

 

The manual says normal operating temp is in the center of the gauge, which on US models is 200F which is where mine runs.

 

90F day here today, and I checked on the way home, and my temp was at 200F the whole way, which as indicated, is the middle of the gauge, straight up and down...

CADman_ks

 

Further to what I said, 90C is also the middle of the gauge (straight up at the top).

 

To the point of needle movement above the 'set' point - whatever that may be. The ONLY time you should see ANY needle movement above the set point is if there is not enough cooling. ie you are pulling a long grade under heavy load such as pulling a trailer AND the cooling system is dirty or partly plugged.
Otherwise, as the motor throws off more heat, the thermostat just opens a tiny bit more and allows more coolant through to be cooled by the radiator etc. As the engine load increases it keeps on doing that until not enough cooling is available from the radiator. Only then does the temp actually rise a measurable amount.

 

my temp gage is always in the twelve o'clock position when warmed up(210f) and stays there

 

This 2011 TDI Sport is my 9th diesel, so I'm not a novice. All my previous diesels had thermostats between 70C and 85C (160F-185F).
//greg//

Volkswagen run their diesel engines at 90 degrees - Helps to achieve an optimal burn. It is perfectly normal. I would only get worried if the hand passed the twelve o clock position.

 

Well, that's consistent with the Jetta 1.9 TDI owners input. Their 12 o'clock position is said to be 90C (194F). But 12 o'clock on my 3.0 TDI is 200F (93C. And my needle runs pretty consistently at or near 210 (almost 100C).

It's either a false indication, or 210F isn't hot enough to trigger an ECM fault. Two VW service managers have failed to come up with an explanation, which is why I'm trying here.

//greg//

 

I believe modern emission controls need higher operating temps. My V-10 has run at water temp 200 and oil temp 200-210 (depends on whether or not I'm towing. I've never seen either go above those numbers even when pulling a grade. This leads me to believe the total cooling capacity is adequate.

I believe the thermostats are electrically operated and controlled by the engine computer. As a result one will not observe the "traditional" changes in water temperature due to thermostats opening and closing.

johnt

 

I put my Innova 3140 on the question, and it shows the coolant rising and falling in the 194-201F window. While the constant rise and fall of the coolant temp was reflected by the 3140, the temp gauge i the dash didn't move a molecule. That tells me two things;
(a) I've got a 195F thermostat, and
(b) the VW temperature gauge is little more than an idiot light with a needle.

I think it's fair to conclude that the idiot gauge needle only reflects temperature variances something in excess of the 7 degree swing reported by the 3140. If I can figure out how to link the 3140 with my PC and make a graph out of that live data, maybe I can come up with a more definitive explanation. But for now I'm satisfied that the engine temp is fine, it's just the gauge that sucks.

//greg//

 

There is another explanation (And I do not discount the claim that the VW gauge is an idiot light with a needle! An apt description.): The OEM gauge may be internally damped to not respond quickly to temp changes. One way to check this is to watch both the OEM gauge and the external readout during warmup. If the gauge is highly damped the reading should lag the external readout by significant amounts.
Also, in order to track, the temp sensor for the external gauge must be very close to the same place in the coolant system as the sensor for the OEM gauge

 

The OEM gauge may be internally damped to not respond quickly to temp changes.

Nope, it's a LCD gauge. Digital input, analog representation. It's the programming of the digital input that apparently influences how many degrees rise or fall will result in a change in the analog representation.

But far as watching the 3140 and gauge relationship from cold, I can't do that safely while I'm driving. That's why tomorrow I'm going to see if it's possible to print out a temperature graph after hooking the 3140 up to my PC. Then perhaps I can figure out the specific number of degrees change that triggers a "needle movement". I know I can print out error and diagnostic codes stored in the 3140, I'm just not sure how much - if any - live data is stored, and for how long. And if it is stored - whether or not I can get a print out.

//greg//