No harm in replacing it, and if it the new lasts another 100k that's what you call "peace of mind"

 

Drove to work today at -27.5C on the highway at 115km/hr. Engine would not warm up! Dang it…what else can it be? I’m sitting at only 60C for 30mins!

I tried lowering the cab temp to 16C, the engine temp went up slightly…to 65ish, but then my windows started to fog up.

 

I’m reading on the forum that our water pump is controlled via a vacuum line? Is the pump normally on or off? I would assume that it fails on…which may explain my situation. But I have no leaks.

Would the remap have anything to do with the thermostat map? Since ours is controlled via a heating element.

 

My wife came in yesterday and said that her temp gage (2015 GLK 250) was reading well below 80. It is pretty cold (for Toronto) at -12C and she couldn't get above 80 Km/hr due to traffic. This morning I dug out my trusty Autel scanner and took off for a drive. After about 10 mins I stopped and checked the top hose - nice and cold so the thermostat seems ok and the cooling fan wasn't moving. Another 10 mins and the temp gage was still only at about 70. Stopped again and did a full scan - all clear , no faults anywhere. On the way home I turned on recirc and within 1/2 min the temp went to about 85, this was confirmed by the Autel real-time data. After a couple of mins my windows started to fog so I turned off recirc. About 1/2 min later the temp slipped to 75.

In the absence of any identifiable faults I can only speculate that the heater core might be oversized and is super-cooling the engine during extreme cold. But we've had the car from new and I don't remember this happening during previous winters. The only difference I can think of is that I did on OE tune with DEF delete over the summer. Wondering if the tune makes the engine run slightly cooler. A shot in the dark but Occams Razor sometimes works.

 

I drove home at 120km/hr for 30mins. Temp did not go above 75C. Outside temp was -21C.

Im starting to think it’s the tune. It also idled slight rough when starting cold. At least the tune made it worst.

 

I suppose that's one way to look at it, but I'd rather say that the engine isn't producing enough heat to maintain the cabin temperature you've chosen. Recirc means it doesn't have to keep heating the air from ambient, but I'm sure you realize that.

If the engine is producing less heat doing the amount same work then it's running more efficiently.

 

A very positive outlook! Hahaha…

Well, I suppose a way to confirm is to reflash the original map back into the ECU. But then I might get the adblue countdown again.

I will have to make some kind of front cover, and hopefully finish installing the webasto this weekend. This kind of extreme cold isn’t good on any car, the GLK is no exception. Just have to find a practical solution.

 

Yes, that's why I tried it.

That might be true to some extent but I'm not sure of the magnitude. I'll contact OE and find out if their tune re-calibrates any sensors related to engine temp (e.g. the CT Sensor). Who knows, they might have overlooked extremely cold ambient when they designed their map..

 

Spoke with Sam (ECU Program) on the phone today. He confirmed that the rough idle is normal in the cold, mine goes away after warms up. He offered to make a stock tune with adblue delete for me to try and see if the warm up issue goes away. I'm still very happy with these guys as they didn't deny anything, the feel I got from them is that they want to help - very rare these days. They weren't going to charge me anything extra to do this.

Today was -14C in the morning and -5C in the afternoon - both trip, the engine warmed up fully (very slow in the morning, but on my way home it was quick). I was talking to a co-worker who had his diesel truck tuned, he said that he noticed a significant difference in how the engine build temperature in the cold weather. His tuner found that it was because the map aims to lower exhaust back pressure - which builds heat. I wonder if the OE tune and my Economy tune uses the same strategy to gain power.

 

I had forgotten about that. My Duramax had a variable vane turbo, and it would close up the vanes on a really cold start to help it warm up faster.

 

That makes so much sense. Heard back from OE and they just asked me if the car was running ok and I told them it was running well. I'll send something off to them with your findings and post their response. This is really interesting stuff. .

 

The engine taking longer to warm up than normal (even in really cold temps) can also be related to the EGR setting. If EGR is turned off, as most tunes do, then the engine exhaust is not being pumped back into the intake and it takes longer to warm up by only ingesting outside, fresh (cold) air.

 

You beat me on that answer andreigbs. Stickman007 i think you mentionned earlier that your EGR is deleted? MY GLK is fully deleted except for the EGR and i have no problem reaching my operating temp. -25C today, driving 5km in the neighborhood to warm things up a little and it only takes 7km on the highway to reach op temp. In the diagram, #12 is what to look for.

 

OE responded:

"Back pressure is always increased with higher boost targets from tuning. There is no change to back pressure at idle or cruise. I do not think this is related to temp."

Seems that we have a difference of opinion or a difference in approach between tuners.

 

EGR would definitely contribute to warm up. I'm glad everyone is pitching in for ideas. I still do not regret changing my thermostat at 148k, but it seems to be the "go-to" answer for a lot of people.

It was 0C this morning and 5C in the afternoon - engine had no issues warming up even in slower speeds. In the city waiting at the lights, temp did not drop below 85C. I still need to find myself an Android device (I sold my soul to Apple) in order to load the OEM tune with adblue delete back on the car. Sam already emailed me that the tune is uploaded to the server and ready for me to flash - these guys are quick and professional! I will try to borrow an tablet or something this week...its suppose to get cold again next week so that'll be the real test.

 

100 percent correct. I believe Sam used software to disabled the EGR.

 

Interesting. I recall (perhaps erroneously) that one of the benefits of EGR is that it lowers combustion chamber temperatures...

 

I think this is true. It increases the air intake temp in order to reduce the combustion chamber temp.

Note - this is getting uncomfortably close to the limits of my technical knowledge but I think that this is a pretty close description..

Cold air is denser than warm air and cooler air is desirable in a combustion engine because it results in greater expansion of the air/fuel mixture during combustion hence more power. This is the purpose of post-turbo intercoolers. A problem arises from this process because high temp combustion generates high NOx emissions. My understanding is that the EGR warms the intake air in a controlled way using exhaust gases in order to keep the combustion chamber temps below the NOx threshold (whatever that is). This balancing act between cooled air input and EGR warming is controlled and depends on throttle input and various temp and pressure sensors.

.

 

I'm remembering more...

My Duramax had an EGR cooler. The cooling was accomplished by exposing the exhaust gas to the coolant, which would warm the coolant. So, cutting out the EGR would eliminate the coolant heating effect from the EGR cooler.

 

Basically, EGR is used to reduce the formation of NOx emissions, which are created when the combustion chamber temperature exceeds 2,370 degrees. Pumping exhaust (EGR) back into the engine helps to cool the combustion chamber because EGR has almost no oxygen in it. Without oxygen, the temperature stays below the NOx-producing threshold, and the emissions coming out the tailpipe are cleaner.

 

No, that's correct, it does lower combustion temps so less NOx emission produced. Coupled with SCR it removes almost all NOx from the exhaust on modern diesels.

 

To quickly heat up engine at the start-up, ECU controls the pump via vacuum line and disconnects it from the impeller via vacuum, so should be OFF. Once engine is hot it should be ON. I assume if the vacuum jacket fails (which is common on these engines) it should be always ON. This is from OM651 Intro brochure:








@stickman007 I'd test the pump with a vacuum pump to see if it holds the vacuum and check the surrounding area if there are any traces of coolant leaking. It's easy to do with only the engine cover removed, don't even need to remove air intake.

Is your car warming up quickly and holding temperature now when we have single digits outside ?

I had similar experiences during extreme cold here in Calgary with my CR diesel Golf and now with GLK Bluetec. The only way to get up to 90C without freezing up inside the cabin was to get the car to a highway for 20-30 min and have the front grill cover on! If I drove around the city roads, at the stoplight coolant temp would start falling down. My wife's gasser Golf warms up much quicker but I can still see temp needle starting to creep down at a particularly long stoplight! Modern diesel engines are too efficient to generate enough heat in ambient temps of -25C, -30C without some serious load. On top of that, all the emissions-related hardware has never been tested in these extreme temps either. So DEF heater/pumps fail, urea injectors freeze and fail, etc...

Here is the front cover for GLK that I have any time it dips below -20C... took a while to get it done but it works:

 

Is your grill cover custom made? Where did you find this? I would be interested in purchasing this.

 

Yeah, custom made. I couldn't find ANYTHING on the market ready for use on GLK at that time so had to make something up. The Sprinter grill cover that MB carries wouldn't fit GLK and it was really overpriced. I've used outdoor A/C cover but any other durable material would work. You can get the tarp eyelets kit from any other hardware store. The hardest part of this mini-project was to make a decent template out of paper/cardboard.

 

Keep in mind that MB doesn't advise the use of winter grill covers, even though there are some available for Sprinters and such. If the temperatures are consistently well below freezing and you're not doing much (if any) highway driving to fully warm up the engine, then a cover helps things get warmer, faster.

BUT... if temps change from day to day or you guys do highway driving regularly, I would caution against a contrived cover that's a pain to put on and take off, which leads to it being left on all the time. That's asking for trouble, IMO.

YMMV