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Found this by accident, I was looking for voltage data to Instrument Cluster (IC)
Attached the WIS.
No wonder : I was trying to correlate the dial with OBD Gauge and indeed seeing 5 C different is so common.
Its kinda scarry, for me the 90 C dial valueunder hard driving if temperature is actually 115 - 120 C ... it maybe too late if something really goes wrong if the dial doesn't show the slow drift temperature rise
It is called "dummy gauge"
For the same reason oil pressure gauges got deleted on most of the cars.
When you have vehicle with cooling problem, you better add a gauge reading ECU.
I used to own Ford 6l Powerstroke, who was notorious for oil cooler clogs.
With small flow the cooler would boil coolant and when it happen to me, by the time the gauge would show red and I could pull over - my radiator was empty.
OE removing a Temp Gauge like my 2011 Ford Fiesta 1.6L Power-Shi-et is a big NO NO and it has no coolant level sensor too.
My 27,000KM but 9 years old radiator hose got an unknown small tear and by the time the overheat warning lamp lighted up, its kind bad.
No deformation/warp on my cylinder head lucky.
I still like the older MB with actual oil pressure gauge and real oil press sensor.
For me an accurate non-dumb-down coolant temp gauge and oil pressure gauge is a must. Because I push my engine hard and my ambient temperature is too hot.
That is why I have bought Banks Data Monster OBD based gauge so that I can install my own oil pressure gauge and can set trigger alarm level and have back up to the coolant temp.
Too bad my engine 3.0 TT probably have the same 2 stage oil pump which reduce oil press at lower RPM as the M276 3.5 NA and I can't get the
alarm to trigger based on 2 parameters like X RPM with Y oil pressure gauge. I really like to trigger low oil at a mere -0.75 BAR from known good at X or Y RPM.
Good thing MB coolant level is at higher elevation than the engine coolant temp sensor, at the least a minor leak can be detected ahead of time instead
of waiting for overheat trigger from temperature sensor ...which by its position being quite high, can be empty of water at the sensor tip and overheat trigger can fail to activate
as sensor tip is reading air and not liquid coolant. How high is your Ford 6L Powerstroke coolant temperature position at engine ? It is surely higher by position than the oil cooler line yes ?
I still like the older MB with actual oil pressure gauge and real oil press sensor.
Define "older"
Even 1987 MB had oil pressure light on electronic circuit, who would delay warning for some time.
I had that circuit malfunction, what made red light to come on each left turn.
Only W123 had real pressure gauge, what lead to several disasters when mechanic forgot to reconnect oil line to the dash gauge.
Oil cooler on 6l Powerstroke was on top of the engine, what don't really matter in sampled situation.
Once the coolant start boiling, the steam pocket will blow the coolant outside no matter where the source of overheating is.
Define "older"
Even 1987 MB had oil pressure light on electronic circuit, who would delay warning for some time.
I had that circuit malfunction, what made red light to come on each left turn.
Only W123 had real pressure gauge, what lead to several disasters when mechanic forgot to reconnect oil line to the dash gauge.
Oil cooler on 6l Powerstroke was on top of the engine, what don't really matter in sampled situation.
Once the coolant start boiling, the steam pocket will blow the coolant outside no matter where the source of overheating is.
No. at least not on US market.
As I pointed above, they had red warning for low oil pressure, who was still "corrected" by electronic circuit.
AMG usually have more gauges, but they were rare here.
My 1998 SL500 had oil pressure gauge, what in hot weather and thinner synthetic oil would show 0 at idle.
No. at least not on US market.
As I pointed above, they had red warning for low oil pressure, who was still "corrected" by electronic circuit.
AMG usually have more gauges, but they were rare here.
My 1998 SL500 had oil pressure gauge, what in hot weather and thinner synthetic oil would show 0 at idle.
W124 dashboard. Looks like it has a pressure gage to me. I know my 1989 190e 2.6 had same which would drop at idle as a function of oil temp and condition.
Older as in my family's W116 280SE ( production to 1978 ), W126 S280SE ( production to 1990) and W123 280E ( production to 1986).
Yes, my friend's W124 300E have true oil pressure sensor and gauge.
So some W124 did have pressure gauges. Were they true gauges?
I sold W124 over a decade ago, so the memories faded, but still remember that oil pressure gauge going to 0 at idle was hot topic on W123 section and R129 section, when I don't remember the subject discussed on W124 section. Red warning light coming on sharp turns was on other hand.
With huge variety of models and option MB makes, lot of things can exist, but what was most common?
Kind of dispute about history in times where modern engines have no oil pressure sensors at all.
No. at least not on US market.
As I pointed above, they had red warning for low oil pressure, who was still "corrected" by electronic circuit.
AMG usually have more gauges, but they were rare here.
My 1998 SL500 had oil pressure gauge, what in hot weather and thinner synthetic oil would show 0 at idle.
Incorrect. They all had oil pressure gauges (were in the US, so I'll leave it at that) as shown in the image above, W123s did as well... read in BAR, IIRC. You wanted a minimum of 1 at idle, and for it to increase with RPM (2 at 2000k and 3 and 3000k). Now they did away with them on W211s. W210 I don't remember.
It was the mid-90s when BMW switched to "buffered" coolant temp gauges on US models... whereas ROW variants did not. Speculation was customer complaints of "too" much needle movement, especially stop/go, idling or long uphills where temps would climb near MAX freaking people out.
There was this case with Jaguar too I read on forums about coolant temp gauge.
If I recall correctly it has colors scale and not detailed numeric values except at the far right, it is clockwise needle movement.
People are so bothered by the gauge showing more "hot" ( not overheat ) color band, as such Jaguar finally shifted the color band to the right and make needle reading
seems at "cooler" zone. LOL.
I love instant non-buffered/non-delayed gauges, except for fuel level.
Its a good pre-warning tool looking at the trajectory of the reading when and if car is driven hard or in a bad traffic jam in a hot country.
In the old days I even have to turn off my main low beam headlight at night during traffic light or slow traffic crawl on a small car with small alternator,
but headlight from H4 of 65/55watt replaced to 100/90watt. Sometime I have to turn off the aircond too, because car is front wheel drive small engine with all electric cooling fan.
Usually 2 fans. 1 for coolant radiator and 1 for aircond evap.
So when power is lacking from alternator, engine is loaded mechanically by aircond compressor and cooling fan speed is not good enough = creeping up slow overheating in progress.
This is when real time old fashion coolant gauge shines.
Remember the days our sedan engine uses viscous coupling engine driven fan ?
Raise RPM to 1,500ish and prevent overheat at bad traffic.... LOL.
Having removed my w123 dash to replace the evaporator I can tell you the gauges are mechanical. Speedometer cable and oil line (oil goes directly to the gauge) are a real pain to get connected.
I also have a 92 Chevy pickup and I am not sure about all the gauges but I do know that when you have the blinker on the voltage will bounce up and down with it, especially if you are running the AC.
Expanding the controls who lie to you, my the "throttle" control is lie as well, on diesels.
It exist on E, but with light car less noticeable, but newly purchased GLE, when pushed 1/4 of pedal will go to 4000 rpm on 1st gear. There is no way around it, unless I want to push the pedal slightly to start moving, let it go for a moment and then push it again.
The 4-cylinder diesel has lousy take off and I think to improve the image, the engineers override the software to redline the engine on 1st gear all the time.
I prefer gentle starts and that can get pretty annoying.
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Found this by accident, I was looking for voltage data to Instrument Cluster (IC)
Attached the WIS.
No wonder : I was trying to correlate the dial with OBD Gauge and indeed seeing 5 C different is so common.
Its kinda scarry, for me the 90 C dial valueunder hard driving if temperature is actually 115 - 120 C ... it maybe too late if something really goes wrong if the dial doesn't show the slow drift temperature rise
I don't understand using the step function in this way ... why not just display the "actual" temperature?
They do this on i think all diesel trucks (non commercial) in NA. The worst is the fake oil pressure. It will read correct oil pressure up until the engine seizes.
Something about how most people dont understand the readings anymore and freak out if a needle moves on the dash. Heck most cant even change there oil much less top off a radiator.
Wow, fake oil pressure. Which engine does that ?
Now with OBD2 data out, at least we can extract "honest" data.
cummins and ford probably chevy as well. Its a algorythm of sorts based on variouse inputs. Has to do with oil pressure naturally reading a low value for certain situations with potential to freak people out even though its totally normal.
Thankfully the cummins has a port you can use on oil filter housing to install a standard pressure sensor.
My guess is customers kept coming in complaining about hi/lo pressures and or temps...
MB figured these are within normal range but people freak out when it gets close to limits so lets just give them what they want a needle in the middle of the safe zone until it is too late.
I got time today to document the white liar in action for you guys.
It has to be photo based, can't be logged on excel file.
The test was stationary one, so it is easy to overwhelm my cooling system.
Zoomed for better view
The lie in progress.....
...
It is very scary for me if I rely on the analog needle coolant gauge.
If I hit 120C and thinking it was 95C as per needle gauge, I probably will warp my cylinder head.
Trend is what is most important for monitoring coolant temperature, not only its actual value.
The problem with cooling system is, when you are running at decent speed, the coolant mechanical pump is doing its job at a good high RPM.
The higher the RPM, the more coolant exchange at the radiator.
The car velocity is very important too, as the electric fan is no better than approx 40 KM/H cooling power in terms of car velocity.
So when you are say at 100KM/H and 1,500RPM or higher, if your engine is actually at 120C and higher where the WIS stated the needle will show true temperature by then ( I hope so ),
you freak out for sure.
You then slow down to stop at a road side. This is where the engine will be hotter by at least 3-4C , because the mechanical coolant pump is too slow at idle speed and
you get no gain from car velocity or wind cooling the radiator.
For me to hit that test of 107C is easy,
Keeping car stationary and revving to 4,200 RPM ( soft limiter ), will raise ECT easy to 104C.
I then let engine idle, and ECT will raise extra 3C. See 2 images below, the green circle #1
Zoomed for better data view
Yes, 3C extra heat to hit 107C for the coolant from simply letting the engine idle when coolant was at 104C.
Slow mechanical coolant pump speed at idle is what made it so.
Green circle #2 is a bit higher RPM needed to cool engine faster. This is because the mechanical water pump at idle is NOT GOOD enough for my climate,
when and if the coolant is very hot. Approx 1,500 to max 2,000 RPM is good by coolant flow to cool the engine based on mechanical coolant pump output.
If your overheating is from a loss of coolant..... sorry, there is no method to cure except engine shut down and pray your cylinder head does not warp.
Does W212 use the electric aux pump to supplement the belt driven pump at low vehicle speed? This is one of the reasons the aux pump is present. If you have an aux pump you can observe state (its voltage) with an OBD device.
Electronic indicator giving false values vs actual measurement is common, same with VAG/Porsche. It’s designed to reduce panicked phone calls to dealers and false alarms for warranty claims by customers whose vehicles are “overheating”.
07-16-2021, 06:45 AM
