Mercedes-Benz Metris Forum banner

how long does it take your metris to warm up?

4K views 13 replies 9 participants last post by  imacd 
#1 ·
I noticed that temp gauge is creeping up way slowly and it takes forever to reach operating temp which is like 90ish on the temp gauge.
today just to conduct an experiment I started it cold at 35 degrees and it didn't get above 60 after 15 min of idling.
should I look into thermostat replacement? or is that typical?
 
#3 · (Edited)
I noticed that temp gauge is creeping up way slowly and it takes forever to reach operating temp which is like 90ish on the temp gauge.
today just to conduct an experiment I started it cold at 35 degrees and it didn't get above 60 after 15 min of idling.
should I look into thermostat replacement? or is that typical?
They all do that. When the outside temperature is below about 40 °F, mine can't maintain 90°C operating temperature driving on surface streets. Especially if the heater is on.

It will warm up with a little load, such as a few minutes on the highway.
 
#5 ·
This should have been a topic last week!

Had my van outside in < 0F weather for a week. Would have been ideal for the warm up test.

I don't think I ever noticed a vehicle ( MB ) not holding temperature below 40F, and I have done some winter driving.

Will try to keep an eye on things before spring comes.
 
#6 ·
Have not bothered to actually view coolant temperature via an OBD2 scan tool in real time. But my 2020 Metris warms up based on the coolant temperature graphic indicating the coolant temperature is in the middle of the temperature range after just a few miles of driving at 45mph.

I don't idle the engine very long after a cold start as I know from experience an idling engine warms up slower than one being driven, even if it is being driven in a sedate manner, which it should be if cold.

Even when driving the van in single digit temps the van warms up in a reasonable amount of time and appears to maintain a good operating temperature.

With my other car I can observe the actual coolant (and oil) temperature and being driven in an urban environment (as opposed to on the freeway) the coolant climbs to around 200F and runs between 200F and 206F (or a bit higher). I would expect the Metris to behave much the same way.

I have also noticed with other cars that getting on the freeway with a "cold" engine and maintaining the legal limit (65mph) it can take the coolant temperature some miles (>10) before it gets to 200F. The engine is just not producing that much HP to maintain the 65mph speed. And this with a car with an engine that produces a max of 707hp. (Dodge Challenger Hellcat.)

Based on what you reported to observe I do not believe the T-stat is a problem. If you can observe actual coolant temperature vs. trying to guess it based on some coolant temperature graphic observe coolant temperature. If even after some minutes of use in an urban setting the coolant temperature is low, and the coolant temperature has been checked and confirmed with another temperature gauge to eliminate bad temp sensor, then there might be a problem.

In this case a tech would use a hand held thermometer to check the temperature at various points of the coolant system to look for any signs of too low (or too high) of a temperature which could arise from a bad T-stat.
 
#7 ·
Ran a quick test today. Parked my van outside in ~15 F weather all day. Tonight I started the engine. It took about 23 min for the dial to reach mid temp. ( on the redisgned dial all mb now have, sigh, 10 o'clock ... not just 9, mid way on the white section )

And, when I think back at a trip two weeks ago, in similar temps, I recall no issue getting heat from the engine nor holding temperature on a 6hr round trip.
 
#9 ·
Attached is a PDF of a graph of coolant temperature behavior from a cold start for a trip that lasted around 16 minutes. It is a real pain to view the graph data on my Windows laptop and get an image created and then transferred to my MacBook Pro.

But I think I managed.

The "trip" graphic data consists of vehicle speed, RPMs, coolant temperature, and I think manifold pressure. I only created an image of the coolant graph.

The trip consisted of around a 6 mile drive from home to a bookstore all on surface streets with a limit of 45mph with a couple with a limit of 35mph. The engine started out cold and I kept RPMs. IOWs no hard accelerations.

Added: I looked at the PDF and when I captured the image it looks like I cut off the last few minutes of the trip. But the coolant temperature at the right most edge of the graph pretty much stayed unchanged for the rest of the trip.
 

Attachments

#10 ·
Running cool as indicated on the gauge seems like a good sign. If the cooling system is doing it’s best work, it’s going to be overachieving, and more easily in cold temps. I’d be curious to see corresponding oil temp readings, and be more concerned if they were outside of optimal range.
 
#11 ·
It is hard to know from just an analog gauge or even a graphic of an analog gauge the actual coolant temperature. With cars I have monitored actual coolant temperature via an OBD2 scan tool and compared the readings in real time to the analog gauge about the best one can hope for using an analog gauge is if the engine is cold, warm or hot.

Ideally the engine coolant temperature should remain rather constant under all conditions. But some cars in my experience were a bit lacking in this regard. They'd run cool in cold weather and hot in (admittedly) real hot weather. Nothing scary but I was rather surprised at how cool the engine coolant remained in cold weather. I expected the T-stat to do its job and close up some and reduce the circulation of cool coolant to keep the coolant temperature higher. The flip side was in real hot weather (116F) the coolant temperature climbed to 226F. But it went no higher.

But that was a car I bought new in 2002. More recent cars appear to be better in this regard. And this includes my 2020 Metris.

With cars that provide an oil temperature I observe this more than coolant temperature. From the oil temperature I know if the engine is cold, warm or hot. Oil temperature tends to lag coolant temperature then in my experience tends to rise above coolant temperature and run higher. This is to be expected because the oil is in direct contact with the hotter parts of the engine, the bearings, the pistons (via oil sprayed against the bottom of the piston), the cylinder walls, valve stems/guides.

Not surprisingly oil temperature goes up quicker when the engine is working harder and is slower to drop when it is not. But an oil cooler affects this. With my Hellcat and its large air cooled oil cooler tended to keep the oil temperature in check, well, relatively speaking. It was always in check but swings were less severe.

With my Scat Pack with its coolant cooled oil cooler it is less effective at keeping oil temperature in check. This is not to say the oil temperature runs away and gets too hot just that it goes up quicker, and once up stays up longer.
 
#14 ·
So I headed up to the food bank with a load of donations this morning.
Rectangle Font Electric blue Number Signage

Not too cold, but snowing and blowing so I just sat a respectable distance behind the snow plow doing about 40mph with the defrost and heating on. I noticed that the engine temp was low, so when I turned off the main road, I did the last 5 minutes with the heating off. When I got there the temp was up to ~ 190.
Gauge Motor vehicle Vehicle Speedometer Automotive design

Had to scrape off the food bank van and move it to get in, so I left the Metris idling for about 5 minutes with the defrost and heating on at ~80. Engine temp dropped to ~140.
Speedometer Odometer Gauge Motor vehicle Measuring instrument

Don't expect it to warm up if it's not burning much fuel and you're extracting all the heat.
(I know, I don't have TPMS with my snows...)
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top