kerrly

Hey folks,

I have a 2010 GLK 350 4Matic. The colder it is, the longer it takes to heat up to temp. (Makes sense) However, I have a remote start and to get it to even produce luke warm air, I have to let it cycle through at least once. Twice on really cold days. I leave the fan on half speed when it's running. At highway speed for more than 15 minutes I can finally get the heat to pump out nice and warm/hot and heat the entire cabin to a comfortable temp, but if I am ripping around the city it will take about 30 minutes before I feel comfortable on some days. I am from Canada so it can definitely get cold here, but I have never owned a vehicle that performs so poorly heat-wise in the winter.

It seems to me like it is getting progressively worse over the years, all be it, it was never that great to begin with. Could be my imagination. I had the low coolant light come on a few months ago, and took it into my dealer. They topped it up for me and sent me on my way. No real issues that I have noticed that could be causing this.

Any other owners experiencing this? Is this a design flaw? Any info would be greatly appreciated. I will be checking this thread periodically, so if you need more info I can provide it.

Thanks!

formerjeepguy

What about engine temperature? Does it take the engine as long to heat up as it does the heater?

When is the last time you changed the cabin air filter?

kerrly

Yes, it seems to be based completely off engine temperature. I meant to put that info in the original post.

The colder the temp the colder the engine temp which makes sense, but it seems to run around 60 - 70 depending on the temp in winter. It will eventually reach the 80 mark after driving for quite a while but really won't get above that. Anything around or above 80 is when the heat will start to pump out fairly warm and make the cabin air heat up. Engine runs at a decent temp (above 80) when the weather is above freezing.

Can't remember when the cabin air filter was changed last but it has been replaced. I should do that again but I don't think that is the cause of the problem as the air flow seems fine. The problem is the air temp.

formerjeepguy

Your engine thermostat may be stuck open. Take it in and have it checked.

aabc

I had exactly the same problem. The engine temperature never passed 80C for 2-3 weeks, then the engine light was on. Replaced the thermostat, everything's back to normal.

Here's how to replace the thermostat.

This is the thermostat.

Here is how to drain the coolant.
https://mbworld.org/forums/glk-class...tructions.html

NYCGLK

def not normal...in city i have hot air after 7-10 min drive, when it's low teens (F). I don't idle the car. I just get in and go (just take it easy while it's warming up).

chuckmahon

Agree that this is a symptom of an irregular state -- at idle my glk is hot in 5-7 minutes even in unbearable cold.

formerjeepguy

That was a good video except the part where he lets the old coolant dump all over the front of the engine and engine bay. It should have been properly drained before he started.

kerrly

Thanks for the replies everyone. I will take it in and have the thermostat looked at.

bop11

Be advised that an idling engine does not produce much heat. Only when you need to pull some power does it start to heat up, so if you start the car and don't drive it all you are doing is washing the oil off the rings and putting unburned gas into the catalytic's. since the engine needs to run rich when cold. You need to start the car, wait a second or two for the oil to fully circulate and then drive away.

rmfnla

It also looks like he used a torque wrench as a breaker bar...

formerjeepguy

Yes, I caught that too. It probably didn't hurt the wrench, but it's still the wrong tool for the job. It bothers me more that he thinks it is ok to make a mess of a car when the engineers provided a clean and convenient method for draining the coolant.

Shrimpboy112

So as the title says my GLK can run for 15 minutes and only blow luke warm heat. The thermostat has been changed and that did not correct the issue. While driving the heat is incredible it’s only an issue during warm up is this normal?

bop11

Run as in driving or run as in idle? Not much engine heat at idle.

Mmr1

Is the radiator fan running ?

Shrimpboy112

Run as idle the heat will not get hot until you start driving it.

Shrimpboy112

I’ll check that tomorrow morning. I have notice that I have to push it all the way up to get a good flow of air coming out the vents. On my E430 i had to replace one of my electric fans to get the AC to work adequately.

Mmr1

Radiator Fan should not be running

Shrimpboy112

Okay I’ll check that. I’ve noticed these cars have a lot of electrical gremlins like my park light in the front right headlight will just turn on with the car parked and doors locked. For a 2010 with 80k miles I’m not impressed at all.

Mmr1

At 32f my 2013 takes about 12 minutes to fully warm driving in the city. If yours takes a lot longer your oil is going to sludge up the motor . If so change it when it looks dirty