W124 high temperature reading

[ash_2009]

Dear all,

Car w124 e220, 1994

Today I noticed the following.

While driving for about 20-25mins in normal traffic I noticed the temperature gauge got up to what I think is 100 (see picture). It never went above that mark ever before but it did not come down as quickly as I expected to as I would have thought the fan would have kicked in and cooled it down.

This car has never had this problem.

Another strange thing is that when I got home and parked the car and left it to cool for about and hour the temperature gauge was now showing just above 80 C. I would have thought that in an hour this would have dropped below the 80 C mark but not 0 C.

I have checked for leaks - none

I have checked coolant level - perfect at max mark.

I checked for oil in coolant (head gasket) - noting (plus the head was done a little while ago)

I did the "carrot" test - this is where I am a little lost. Car off/engine cold I can spin the fan both directions freely no problems. Then I start the car (engine cold) and place the carrot on top of the fan blades and it is sliced
off but fan stops. Then got the engine nice and hot (80C) and again placed carrot and again top was sliced but fan stopped again. Lost lost lost.

Also for good measure I have removed the two fan switch connections which are under the black cover on the front of the head and gave a clean with contact cleaner. While doing this I by-passed the fan sensor with a piece of wire and the fan spins although I would have thought much faster!! Further I measured the volatage across the sensor and got a reading of 5.0V. The fuses were also checked and seemed fine.

So I am trying to narrow the problem down and I could be wrong but the three below comes to mind after reading several posts here.

1) Thermostat gone - replace??

2) Fan temp sensor gone - replace??

3) Radiator blocked - needs a good clean??

4) Viscous fan coupling gone - replace??

Any thoughts

Ash

 

[ash_2009]

Forgot here is the picture attached.

Ash

 

[brucemillar]

The outside temps here in Kent today peaked at around 32c. It may simply be normal that your gauge is reading "higher"

Is there a Winter and Summer setting on your air intake?

 

[ash_2009]

The outside temps here in Kent today peaked at around 32c. It may simply be normal that your gauge is reading "higher"

Is there a Winter and Summer setting on your air intake?

I dont think so. I am really not sure if my engine has this setting.

Any how I can check please??

Ash

 

[brucemillar]

Ash. I believe that that if it has it is a marking on the air intake, Hot/Cold or Winter / Summer. There will then be a lever or a swivel mech on the air intake. Basically it restricts the air intake (or opens it out). Have you got an owners manual?

 

[CreosoteChris]

The outside temps here in Kent today peaked at around 32c. It may simply be normal that your gauge is reading "higher"

I have a 93 W124 Coupe with the same engine, and the temp reading is very stable, maybe settles a tiny bit higher (85 instead of 82) on a really hot day. Never seen it get anywhere close to 100.

Unfortunately, since it's never been problematic, I don't really have any insight into diagnosing your issue.


Cheers

Chris
93 220CE, auto, red / black leather, 116k, Manchester

 

[ash_2009]

Ash. I believe that that if it has it is a marking on the air intake, Hot/Cold or Winter / Summer. There will then be a lever or a swivel mech on the air intake. Basically it restricts the air intake (or opens it out). Have you got an owners manual?

Yes I think I do so will dig it out and have a read tomorrow thats if I can find it

 

[WDB124066]

I have a 93 W124 Coupe with the same engine, and the temp reading is very stable, maybe settles a tiny bit higher (85 instead of 82) on a really hot day. Never seen it get anywhere close to 100.

Unfortunately, since it's never been problematic, I don't really have any insight into diagnosing your issue.


Cheers

Chris
93 220CE, auto, red / black leather, 116k, Manchester

Is that with AC on, nice and cool inside...

 

[dinoy]

if it happens again another test for you. is switch the heater on full heater setting. i know u will get roasted. the temp will fall through.

to stop hitting the top and cool down to normal temp to avoid hitting the top of the dial

 

[hotrodder]

So I am trying to narrow the problem down and I could be wrong but the three below comes to mind after reading several posts here.

1) Thermostat gone - replace??

2) Fan temp sensor gone - replace??

3) Radiator blocked - needs a good clean??

4) Viscous fan coupling gone - replace??

Any thoughts

5) nothings wrong? It was a hot day and the engine got a little hotter than usual... If you've got A/C and had that cranked up i really wouldn't worry as it would compound the extra load on the cooling system because the condensor is in front of the rad i.e. it's preheating air that goes through the rad. If you don't have A/C or it's broken then i still wouldn't worry but it's more likely that something isn't quite 100%

While thermostats are sold as 82° or 87°C or whatever that refers to the temp they start to open. The fully open temp is more like 102°C
The engine driven fan lock up temp is in the high ninties to something like 104°C. Your temp gauge is about a needles width below 100, the viscous fan in mine locks up properly at around a needles width above 100° and the leccy aux fans in front of the rad (used mostly for AC) only kick into high speed/speed up if the coolant temps reach ~107/110° and cut out when the coolant drops to 100°. That's about the time i'd start getting fidgety and think about suffering the heater personally.
Mines a 320, IIRC the 4 pots have one larger aux fan instead of two smaller? If the shorting a fan switch got the main engine fan to cut in you have an electromagnetic clutch

If the 'stat was dead it would either take ages to warm up (stuck open/partially open) or boiled* over extremely quickly if stuck mostly shut. A new rad might improve things in hot weather but if it was properly manky i'd have thought you would have seen higher than usual coolant temps before today. You'd hope whoever did the h/gasket flushed the cooling system thoroughly before passing the rad as fit but that said if the gasket was done due to oil/coolant mixing it can take several flushes to get rid of all the 'mayo'
Good chance the fan clutch is tired if there's no history of it being replaced but as i read things the engine didn't get quite hot enough for it to lock up properly

* 50/50 water/antifreeze boils at ~107°C at standard pressure. The cooling system is pressurised raising the boiling point to over 120° assuming the rad cap is healthy. One of the reasons the cooling system is pressurised is heat soak i.e. switch off a hot engine and the coolant temp will initially rise. Showing 80ish an hour or so after switching off sounds normalish for the ambient temps to me... stopped for a chicken shish on my way home this evening, showing around 85ish when i switched off and virtually 100 when i started the engine 10mins later. Unfortunatly for me the dash also lit up like a Christmas tree and i now need to rebuild or replace the alternator

 

[Auto-mobile]

That's fine, I'd only be concerned if it was 100c +

 

[GP801]

Our 280 did this recently. Hot day around 30degrees sat in a queue to get off the A1 near Florence. Gauge reached 100 which it has never done before but we were stationary half an hour or so with AC running. Turned the heater on and it dropped down and then quickly dropped back to normal once on the move again. I suspect yours is behaving normally.

 

[ash_2009]

5) nothings wrong? It was a hot day and the engine got a little hotter than usual... If you've got A/C and had that cranked up i really wouldn't worry as it would compound the extra load on the cooling system because the condensor is in front of the rad i.e. it's preheating air that goes through the rad. If you don't have A/C or it's broken then i still wouldn't worry but it's more likely that something isn't quite 100%

While thermostats are sold as 82° or 87°C or whatever that refers to the temp they start to open. The fully open temp is more like 102°C
The engine driven fan lock up temp is in the high ninties to something like 104°C. Your temp gauge is about a needles width below 100, the viscous fan in mine locks up properly at around a needles width above 100° and the leccy aux fans in front of the rad (used mostly for AC) only kick into high speed/speed up if the coolant temps reach ~107/110° and cut out when the coolant drops to 100°. That's about the time i'd start getting fidgety and think about suffering the heater personally.
Mines a 320, IIRC the 4 pots have one larger aux fan instead of two smaller? If the shorting a fan switch got the main engine fan to cut in you have an electromagnetic clutch

If the 'stat was dead it would either take ages to warm up (stuck open/partially open) or boiled* over extremely quickly if stuck mostly shut. A new rad might improve things in hot weather but if it was properly manky i'd have thought you would have seen higher than usual coolant temps before today. You'd hope whoever did the h/gasket flushed the cooling system thoroughly before passing the rad as fit but that said if the gasket was done due to oil/coolant mixing it can take several flushes to get rid of all the 'mayo'
Good chance the fan clutch is tired if there's no history of it being replaced but as i read things the engine didn't get quite hot enough for it to lock up properly

* 50/50 water/antifreeze boils at ~107°C at standard pressure. The cooling system is pressurised raising the boiling point to over 120° assuming the rad cap is healthy. One of the reasons the cooling system is pressurised is heat soak i.e. switch off a hot engine and the coolant temp will initially rise. Showing 80ish an hour or so after switching off sounds normalish for the ambient temps to me... stopped for a chicken shish on my way home this evening, showing around 85ish when i switched off and virtually 100 when i started the engine 10mins later. Unfortunatly for me the dash also lit up like a Christmas tree and i now need to rebuild or replace the alternator

Thanks Hotrodder,

All points well noted. I did in haste I must admit order a thermostat so I shall keep it for a while or maybe since I have it just fit it.

My car has NO ac and has the single fan.

Looks like I shall just drive around but keep an eye out on the gauge. If it gets too hot since it a convertible, I shall just open up he hot hair flow inside

When the head gasket was done, it was washed through well and done by a member on this forum who has been highly recommeded by many merc owners.:bannana:

Thanks

Ash

 

[CreosoteChris]

Is that with AC on, nice and cool inside...

No AC installed - so on the rare days in Manchester when it's hot and sunny, it's roll down the windows, open the roof, and do that pillarless coupe almost-a-convertible thing.

Works pretty nicely actually, I don't find that I'm bugged by the absence of AC.


Chris
93 220CE, auto, red / black leather, 116k, Manchester

 

[WDB124066]

No you wouldn't be Chris it is a great "mode" with the roof up and windows down. In summer it is the best for me too because with the roof down it is just too hot and inconvenient in town.

I was wondering if your cooling system could cope that well with the added input of the AC. I think most will see 100 at least once or twice in summer probably in stop start traffic with AC on 2 or 3, windows up trying to stay cool. If you were managing 85 under those conditions that would be doing pretty well!

 

[WDB124066]

You need to get the temperature/pressure switching point data sheet for your cooling system. It will tell you what temps the fans starts, stops.
Does the electric fan roar when you short it?

Head jobs seem to increase the temp for some unknown reason.
130 is over heating – 95 isn’t even though it has never done this before. If your Mech fitted a new stat for example the MB ones are now 87 for the 6 cylinder up from 85, this shows on the gauge as a slightly higher running temp. Could be the same for the fours.
Did you check the fuses on the fan relays in the electric box behind the fuse box...?
Where is the air entering the air filter box from...?
Carrot test is done when VC is engaged, i.e. hot.

 

[CreosoteChris]

I think most will see 100 at least once or twice in summer probably in stop start traffic with AC on 2 or 3, windows up trying to stay cool. If you were managing 85 under those conditions that would be doing pretty well!

Today was by far the hottest day of the year here in CreosoteVille (a.k.a. Manchester) and during my trip home from work I was stuck in a queue for 15 mins due to an accident in lane 1.

In fake-convertible mode with the windows and sunroof open, playing Howlin' Wolf (but not very loud - that would be vulgar), in that queue the temp got to maybe 86-87 on the scale, difficult to tell because - as you know - it's not calibrated in that area.

I guess it would get a bit warmer under the bonnet with A/C running, if that was fitted.

Chris
93 220CE, auto, red / black leather, 116k, Manchester

 

[RichardF]

320 SL (R129) ambient temp 35c, roof down A/C full blast stop/go traffic, goes to around 100c. Once up to speed settles down to just around 85-90c.

A/C off maybe 5c less.

110c to 120c, worrying, over 120c too hot.

 

[syncropaddy]

Just flush out the system and it'll be fine. That temp reading is fine. I have 3 x E220 and they all do that.

 

[ash_2009]

You need to get the temperature/pressure switching point data sheet for your cooling system. It will tell you what temps the fans starts, stops.
Does the electric fan roar when you short it?

Head jobs seem to increase the temp for some unknown reason.
130 is over heating – 95 isn’t even though it has never done this before. If your Mech fitted a new stat for example the MB ones are now 87 for the 6 cylinder up from 85, this shows on the gauge as a slightly higher running temp. Could be the same for the fours.
Did you check the fuses on the fan relays in the electric box behind the fuse box...?
Where is the air entering the air filter box from...?
Carrot test is done when VC is engaged, i.e. hot.

Thanks for that

I will check the fuses and make note of other points you have mentioned here.

Cheers

Ash