Running hot

Hi, recently I noticed the temperature gauge on my 2012 TDI Passat increasing past 190F when I'm in 6th gear (stick shift). Not sure I paid too much attention to it before because I'm not on the freeway a lot, but today the gauge went above 190 and seemed to keep rising past the first notch, so I quickly downshifted to 5th and after a couple of minutes it was back to 190. Coolant level and oil level are good.

My wife's 2010 TDI Jetta DSG doesn't move past 190 no matter what. Any ideas what's wrong with my Passat?

how is the heat on the passenger vents? a clogged heater core can restrict coolant flow and effect the cooling capacity:
https://www.youtube.com/watch?v=sG7ni0lEr94

Coolant loops have become notorious for issues on the Passat.

How many miles on the car?

Do you have any of the emission fixes? Reports of clogged heaters cores on the CJAA have caused coolant boiling and codes in the EGR cooler, replacing heater cores fixes the issue but probably won't permanently fix the issue.

55k miles on the car. Apparently there is no emission fix yet for the stick shift.


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The gauge starts to move above 190F when the actual coolant temperature reaches 226F and it continues up from there.

Several of us have commented previously that the Passats run very hot compared to all other TDIs, which seems to be by design based on the thermostat's operating specifications. While climbing a grade, it is normal for a Passat to reach 225F or slightly higher, quickly falling back down when engine load is reduced.

Is this a new problem for you? Were you climbing a grade at the time or were you on flat ground?

I recommend installing a ScanGaugeII and monitoring coolant temperature, boost pressure and exhaust gas temperature. If you can report some more specific data back, we can help you determine if this is normal or if your car needs some attention.

I don’t drive in 6th very often, only a few times and I didn’t notice anything before, although I wasn’t looking for anything, so I’m not sure if it’s new or not.

Recently while crossing a long flat bridge with a headwind I was in 6th doing about 70 and noticed the needle started to climb. It went above the first notch after 190, so I downshifted and it went back down.

Then last night I was driving on the freeway, up a slight incline and I shifted to 6th at about 75, and it started to do the same. I shifted back to 5th and it went down again.

RPM is at or below 2k in 6th gear unless I’m doing above 70, but it’s always telling me to upshift to 6th.

I have read some posts about this engine running hot but it doesn’t seem right that the gauge would rise during normal driving.


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Holding cruise at 80 up a 5% grade the needle still shouldn't move, it's not normal vs what the dealer should say.

Flat at 70 even with a head wind, you're using so little fuel it shouldn't move.

I'd have the coolant system checked out, my guess is it will only get worse.

Easy cheap would be get up to temp let idle, blast the heat (prob something you don't do too offten if you're still in CA) feel for heat in the cabin it should bake you out if not, then pop the hood and touch the both hoses by the firewall, see what they feel.

Ours will sometimes cruise on the flat Ohio Turnpike at 218F, which is only a few degrees away from the gauge moving. The same road during a regen is closer to 222F. It's done that since it was new and so have many others who have reported here. In all of our trips, our car has only made the gauge move two or three when climbing grades at 75 MPH in top gear. Others have reported more frequent gauge movement under similar high load conditions.

I'll agree that what the OP is describing is unusual, but I'm not ready to consider it outside the realm of normal until we get some more information about this car's normal operating temperature (as reported by over OBD2, not the heavily buffered dummy gauge). As long as you aren't exceeding the low 230s and your gauge doesn't climb when the car is under light load, I wouldn't worry about it yet.

If the gauge only moves when the temp is >225, how do I approximate the temperature when it does climb above 190? Is 1 notch above 190 actually 230?


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I don’t know the exact conversion, for lack of a better term... you really have to use something to read the OBD2 data and give you a digital display of the actual temperature.

I got mine hot once running grill covers on the highway in warm weather in the spring. The gauge hash marks are all 10 degrees apart to 250 which is redline. The gauge just doesn't start moving from 190 for a while and then picks up speed quickly. I got up to 240 on my Scanguage and it matched the factory 240 position

Look in the coolant reservoir. Is the coolant nice and pink or darkish orange? Any sediment in the bottom?

reilljp said:

If the gauge only moves when the temp is >225, how do I approximate the temperature when it does climb above 190? Is 1 notch above 190 actually 230?

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I recall on our car one notch above 190* is about 227*F.

I've also noticed that as the car has gotten older the temps have gotten just a little bit higher under moderate loads... 1 or 2*F.

-J

IE the cooling system is getting junked up with "lifetime" coolant.

740GLE said:

IE the cooling system is getting junked up with "lifetime" coolant.

Click to expand...

If you're responding to Jason, not necessarily. It could just be the thermostat aging, allowing slightly higher operating temperatures than when it was new.

For those who don't know, the Passat has a widely variable thermostat that none of the other TDIs have (except for maybe the 2015s, which I know very little about). The hotter the system gets, the more it opens. It is designed to increase engine temperature under high load in order to maximize efficiency. To those who are used to engines operating at a rock solid 190F (like the ALH engine), this is very unusual and can cause concern.

That said, Volkswagen definitely has a coolant problem with the commonrail TDIs, and Passats in particular. Reasonable speculation believes that the high EGR cooler temperatures result in the coolant breaking down and forming solids that subsequently get trapped inside of the small passengers of various coolers (heater core, EGR cooler, oil cooler, and possibly the main radiator itself).

But as I said, our car has behaved this same way since it was new. It has also not suffered from a clogged heater after 5.5 years and 111,000 miles.

I drove about 5 miles in 6th gear yesterday and the needle didn’t move - flat road at 70. Anyway, I’m taking the car in on Friday, so I’ll post an update afterwards.


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I don't know what you're using to post, but your apostrophes are turning into "’"

I’m using an iPhone on Tapatalk.


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740GLE said:

Holding cruise at 80 up a 5% grade the needle still shouldn't move, it's not normal vs what the dealer should say.

Flat at 70 even with a head wind, you're using so little fuel it shouldn't move.

I'd have the coolant system checked out, my guess is it will only get worse.

Easy cheap would be get up to temp let idle, blast the heat (prob something you don't do too offten if you're still in CA) feel for heat in the cabin it should bake you out if not, then pop the hood and touch the both hoses by the firewall, see what they feel.

Click to expand...

I checked the heat and it’s blowing hot on both sides.

Would it be normal to expect the gauge to rise under a decent engine load? It’s not an automatic so it’s not downshifting unless I downshift.

It would seem to me that the gauge would never rise unless there is a problem, even under a decent load, then again this is my first diesel.


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740GLE said:

IE the cooling system is getting junked up with "lifetime" coolant.

Click to expand...

No I think it's just the thermostat aging a little bit. As 'dub noted, it's a screwy design that set with a wide operating range and it takes a lot of heat to make it open fully.

-J

So is it a flaky thermostat or solids from coolant? I guess no one really knows

http://forums.tdiclub.com/showthread.php?t=480550&highlight=coolant

The coolant forms solids in it that clog the small passages in the heater core - I'm sure you're familiar with the heater core recall by now. In addition to clogging the passages in the heater core, these solids also clog passages in the EGR cooler and likely in the oil cooler (both coolers have similar sized passages to the heater core). To date, Volkswagen has refused to acknowledge issues with these latter two coolers.

Click to expand...

http://forums.tdiclub.com/showthread.php?t=470851&highlight=coolant

Here's another one with sediment in expansion tank.

It is worth checking.

Our '12 seems to have been made early enough that it doesn't have the coolant sludge problems. The coolant tank is still clean.

-J

VeeDubTDI said:

Ours will sometimes cruise on the flat Ohio Turnpike at 218F, which is only a few degrees away from the gauge moving. The same road during a regen is closer to 222F. It's done that since it was new and so have many others who have reported here. In all of our trips, our car has only made the gauge move two or three when climbing grades at 75 MPH in top gear. Others have reported more frequent gauge movement under similar high load conditions.

I'll agree that what the OP is describing is unusual, but I'm not ready to consider it outside the realm of normal until we get some more information about this car's normal operating temperature (as reported by over OBD2, not the heavily buffered dummy gauge). As long as you aren't exceeding the low 230s and your gauge doesn't climb when the car is under light load, I wouldn't worry about it yet.

Click to expand...

I find this bizarre as I travel the Ohio turnpike every day. My 13 ran at 202 (per scangauge) and never moved, even during a regen or pulling a trailer with 1000 pounds on it. My 15 runs at 191-193 on flat ground, up hill, during a regen, or while eating French fries, whether the ambient temp is 40 or 90.

2012's had G12++ non organic
2013+ had G13 organic

Locoelectrician said:

I find this bizarre as I travel the Ohio turnpike every day. My 13 ran at 202 (per scangauge) and never moved, even during a regen or pulling a trailer with 1000 pounds on it. My 15 runs at 191-193 on flat ground, up hill, during a regen, or while eating French fries, whether the ambient temp is 40 or 90.

Click to expand...

Thank you for that information. That is how I would expect my car to drive. I could not get to the dealer on Friday so I still do not know what is causing the issue.

I am learning a lot about the cooling system, thanks to this discussion.

I really appreciate all the information posted.


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jrm said:

2012's had G12++ non organic
2013+ had G13 organic

Click to expand...

Can you explain the difference or is there a thread I can read about this? Should I switch to G13 organic?


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copy and paste from old thread from 2012 i had bookmarked- if anything stick with G12++

Here’s some interesting info from a Skodaparts.com site:
G13 coolant additive provides the same exceptional cooling and antifreeze performance as G12++, but is manufactured in an environmentally sustainable way, using glycerin instead of glycol. Glycerin, a bi-product of biodiesel production, is much less harmful to the environment than glycol-based products, which are produced from mineral oil. In comparison with the manufacture of traditional coolant additive, it is estimated that G13 production will produce 11 per cent lower CO2 emissions.

So there is a difference in manufacture, but it may not matter in actual use, and the final product may be identical. What I suspect is that VW isn’t yet able to produce enough of the G13 to supply markets outside of Europe. It could also be that different markets use coolant sourced from different suppliers, and suppliers for the US aren’t yet capable of producing the G13.

Locoelectrician said:

I find this bizarre as I travel the Ohio turnpike every day. My 13 ran at 202 (per scangauge) and never moved, even during a regen or pulling a trailer with 1000 pounds on it. My 15 runs at 191-193 on flat ground, up hill, during a regen, or while eating French fries, whether the ambient temp is 40 or 90.

Click to expand...

The 2015 has a completely different design. You can’t really compare the two.

VeeDubTDI said:

The 2015 has a completely different design. You can’t really compare the two.

Click to expand...

What about the 2013 I had for 80k miles?

Locoelectrician said:

What about the 2013 I had for 80k miles?

Click to expand...

I find it unusual that your temperature doesn't increase even during regeneration. This is pretty atypical behavior for a CKRA engine.

It would sometimes move maybe 1 degree, but never even close to the temps some people report. Now, all my driving is highway so maybe the cooling system works better at speed. Although I’ve seen it Regen around town and the temp doesn’t seem to climb then either. Using a scangauge 2.