Coolant Temp

[TonyJetta]

Background:
2006 Jetta TDI, original owner, 279k miles.
Just replaced timing belt - every belt done by myself - kit from IDparts

Included with this timing belt, beyond the usual:
water pump
serpentine tensioner
thermostat
thermostat housing


I'm inquiring about normal operating temps:
@ 70MPH or less, climbing hills, flat, terrain just doesn't matter nor does ambient temp - coolant temp is 188 - 194.
@75MPH, climbing a 3-4% grade (estimated), coolant temp is 188-194, so long as the ambient temp is less than 100F
@75MPH, climbing a 3-4% grade (estimated), ambient 100-108F, coolant temp starts at 188-194, on the flats, as the grade increases, so does the coolant temp. I've seen it as high as 210F.


Through all these situation the dash gauge stays at 190F. This indicates to me that the temp gauge is dampened.



So, my question: Is 210 normal, when climbing a slight (3-4%) grade in > 100F temps? If so, what should be my upper limit?


TIA,
Tony

 

[turbodieseldyke]

The red zone is pretty high on the gauge, like 250 or 260F? I would guess 230 is where to start worrying, but I'm not an auto scientist.

This is disappointing to hear. I recently bought a 2006, and was hoping the temp gauge was more honest than the Mk3's.

 

[Henrick]

My temp gauge shows true temperature. What I can say, it depends on driving style, as well as hill climbing, long downhills, etc. The thermostat is 92 *C (replaced a few months ago), I can see temperatures between 89-98 *C.
During a regen at certain conditions I observed 105 *C once.

Convert it to your degrees and you get the numbers.

 

[Mach1]

Tony..yeah I hear ya on the gauge..Mine goes up to 190 and stays right there, I don't think I have seen anything over that??

And its summer here as well, I have a 10 degree (easy) that I go up regularly and it doesn't move, with AC going..

I have 200000 on mine as well and finally replaced the AC fan, I went cheap(bad move).

Alright lets talk, so I am to understand you see 210 on the gauge or VCDS? is it just lately since you did TB? did you use an OEM thermostat?

OK, so what am I getting at? Heres my thoughts..if you used a different then OEM thermostat this could cause minor differences...If you just did the TB and possibly hasn't purged all air from coolant then this will cause inconsistancies as well.

And another question(sorry)..did you set the timing and injector preload after the TB job which would affect WT...

Hope this helps or at least gets you thinking and understanding a little bit more...

If you have VCDS you could do a test to see what the differences are and gain a conclusion.

 

[Mach1]

I am sorry got off topic, I was thinking you were asking about why there were delta temp between gauge and wagcom...yes I would think 210 is pushing limits, most diesels in my background are under 200f. I know of a few where modders were trying lower coolant temps with cooler thermostats in order to get better Fuel economy..they were down to the 170-180 range. these were unit injection, non egr, non clean diesel.

Although with the additional strains we see on ours, I can see and accept higher temps. I did watch my today quite carefully and still observed 190, mine seems like it goes to 190 and then just locks there. It was at 100f AC max 80mph getting into turbo and still only 190.

Now I do have my tuned very well and running top notch, radiator is clean and recommended coolant. Fans working tires inflated, I guess I need to drive with vagcom and see delta temps, cause I didn't realize there was that much difference.

So thx for bringing it up and sharing info.

 

[TonyJetta]

All,
Thank you for the replies!


More info:
The factory gauge never budges off 190F. EVER!


I know, and reluctantly accept, that factory gauges are heavily damped to ONLY indicate serious problems. This is in the realm of the general public, and issues associated with that generality,



In my case, I'm trying to make sure I don't have an issue, or find it before it becomes a show-stopper on the side of the road.


While I do have VCDS, for situations like this, I find it easier and frankly more convenient to use my cell phone with a bluetooth scan tool: OBD MX - They are a little procey, but I've had no issues with mine over the last ~4years, I've tried the <$10 generic ones; they were either DOA or died in a week or two.


At any rate, I'm trying to gauge whether or not there is an issue here that needs to be addressed or not.


Timing - Proper lockdown tools were used.
Injector preload - Nope; last changed the camshaft ~80k miles ago. It will probably be due at 300k - time will tell.
I have NOT check torsion.



Ambient temps in southern AZ can run as high as 120F or more.


When ambient is over 100, up to 108, I've seen coolant temps on my ODBII tool, as I previously indicated, climb up to 210F.


The radiator was replaced ~4 years ago - ~100k miles ago.
The condenser was replaced April 2017 - At that time, I did not see any airflow blockage of the radiator.


Ultimately, I'm wondering if I need to consider changing the oil cooler or the oil pump?


I Have verified that there is nothing blocking the radiator.


These operating temps are consistent before and after the thermostat change. FYI...I did remove the OEM thermsat with this timing belt work; it had 278K on it!


Thanks for the replies!
Tony

 

[35 Yr Dsl Veteran]

So, my question: Is 210 normal, when climbing a slight (3-4%) grade in > 100F temps? If so, what should be my upper limit?


TIA,
Tony

Water boils @ 212 F. Coolant boils at a much higher temperature, like 260 or something, so nothing at all to worry about!

 

[relumalutan]

All I can say about the analog coolant gauge in 06 Jetta is that it is misleading. Living in MI, I have completed blocked the air flow to the radiator in the winter, trying to keep the coolant warm (for cabin heating purposes). I have monitored the coolant temperature of the coolant on the MFD via the Polar FIS interface. The analog gauge goes to 190F and remains there until the coolant goes way past 245F. In my opinion that is misleading.

 

[TonyJetta]

So, we all understand that the factory gauge is heavily damped, and therefore misleading.
I also agree, than anything less than ~240 is acceptable, so long as the cooling system is known to be in good working order.


I am trying to understand the normal operating temp range for the '06 TDI Jetta? Particularly in the summer, @ >100F ambient.


Thanks to everyone that has replied.


Tony

 

[325_Guy]

I've had a Scangauge displaying actual coolant temperature since 2011. I live in a similar climate (West Texas) and what you posted matches what I've seen from my own car over the last eight years.



Nothing whatsoever to worry about. Kudos for being aware!

 

[Mach1]

I think 240 is pushing the limits for damage, I would say anything over 210-220 is pushing it.

I like 160-190s for my diesel mods temps, that's at 90 degree and 1400 exhaust, AC on high. The lower the temps the better the fuel economy and power and longevity.

Tony, I am very lazy tech, I like to take care of the easier, less costly, less labor problems first. I would absolutely set injector preload, set engine timing, make sure all filters are good, oil is satisfactory, coolant life and level before I spent any money to change anything else.

These can all contribute to elevated engine coolant temps. plus they need to be done anyway, then you can start to diagnose from that point.

hope this helps.

 

[TonyJetta]

325_Guy, thanks for the reply and validation - That's what I'm looking for!

I think 240 is pushing the limits for damage, I would say anything over 210-220 is pushing it.

Tony, I am very lazy tech, I like to take care of the easier, less costly, less labor problems first. I would absolutely set injector preload, set engine timing, make sure all filters are good, oil is satisfactory, coolant life and level before I spent any money to change anything else.

These can all contribute to elevated engine coolant temps. plus they need to be done anyway, then you can start to diagnose from that point.

Mach1,
I adjusted the injector preload when I changed the cam, 80k miles ago.


If I find some time this weekend, I'll look at the timing. I am doing a 20k maintenance this weekend; oil change, oil, air & fuel filer change.



Thank you all for the replies!
Tony

 

[Mach1]

I just mentioned those checks first cause they can all affect coolant temp, the timing is huge on coolant temp...good thoughts..

I was just checking on the preload cause it looks like it gets skipped as for the timing..I should have known better as the old timers understand.

FWIW..I am a MPG guy as well as longevity, therefor I am going to keep those temps down. And then Texas temps and AC follows as well...