Cooling on W202 C280 V6

[Grahamcol]

Hi,
My C280 coolant temperature gauge seems to run very slightly hotter than I would expect now the weather's getting milder. In normal traffic it sits ever so slightly above the 80 degree (halfway) mark which I still consider normal. In stop start traffic it rises to just below the 100 degree mark (3/4 mark) at what I would estimate to be 95 degrees. Again, I'm not really concerned. However, by this time the electric fan has cut in but it often doesn't cut out again until the car hits a clear road again when normal ram effect of the cooler air brings the temperature down. Until the open road is reached the temperature gauge seems to indicate a more or less constant 95 degrees whereas I would expect the fan to bring the gauge down, cut out and then cut in again if and when the temperature rises. I might add that the car never overheats or goes over 95 degrees, it's just that I would expect the fan to cut in and out under stop/start situations but it often doesn't. Maybe it's a 2 stage fan and goes faster if the temperature rises further to a certain level (above that currently experienced) but I just don't know.
Is this all just normal. Anyone got any ideas please ?

 

[lynall]

Sounds like viscous fan hub to me, mine went the same and wifes old e320, only started running a little hotter as you say, new hub bought temp back down to 85 all the time with occasional bursts above 90.

When engine hot and switched off fan should be a little stiff if it turns to freely its had it.



Lynall

 

[Grahamcol]

Thanks but mine only has electric fan, no viscous fan.

 

[vijilants]

Sounds like the thermostat might not be opening fully or sticking, or the sensor that triggers the fan is malfunctioning if it is not cutting in at the specified temperature.

First id get a voltmeter and pop it onto the fan contacts and ensure that you get voltage at the specified operating temperature.

If that is ok, the fan should cut in.

However, the car is nowhere near overheating

 

[Grahamcol]

Thanks Desilva. The fan does in fact cut in ok but I'm slightly bothered that it doesn't seem to bring the temp down and cut out again until moving along normally again with ram effect. All it seems to do is stop the car from getting any hotter. As you said, the car nowhere nearly overheats at all, it's just that it doesn't do quite what I would expect.

 

[vijilants]

If the fan is cutting in ok, I'd probably say that the thermostat is sticking / not opening fully.

If the car is still running on its original thermostat I'd go in that direction.

 

[Grahamcol]

Thanks again, I'll consider doing that then

 

[recycled]

Is that not normal? In stop start traffic, it should rise a bit higher. in normal driving 80 degrees is right.

 

[vijilants]

Thanks again, I'll consider doing that then

Graham,

I wouldn't let this issue stress you out or go out of your way on this one.....you are way within the engine's operating area .

What I failed to add was if you have a single electric fan, it would also double up for the aircon system, so if you have the aircon running the fan will come on and stay on longer.

 

[Adam230K]

Your car is ok mate, thats well within normal operating temperature

 

[Alps]

temps seem ok, and its a 280 straight 6 you have Not a V6

 

[KillerHERTZ]

temps seem ok, and its a 280 straight 6 you have Not a V6

Year 2000 C280 would have been a M112 V6

 

[Grahamcol]

Thanks to all who replied. Alps, it's a V6 not a straight 6. Anyway, I'm quite happy about matters at present and as some of you have said, it's nowhere near overheating. I'm going to leave well alone and just enjoy. It's a lovely car and a real pleasure to own it / drive it. Thanks again.

 

[Alps]

i stand corrected

 

[stevesey]

Thanks but mine only has electric fan, no viscous fan.

Are you sure? My 240 has both. Difficult to miss, or has it been removed I wonder?

With the viscous fan mine sits at just above 80 whatever traffic is like - but your's is behaving like a FWD car with just an electric fan (apart from as you say the elctric fan failing to actually lower temp - just stopping the increase).

 

[KillerHERTZ]

Later models have no fans, like mine:

Where as yours has:

 

[stevesey]

Is it really that simple - seeing pictures here and on ebay the fans/no fans question has always puzzled me.

 

[KillerHERTZ]

Earlier ones with no fan's most likely have no air-con...

 

[stevesey]

Even then it doesn't seem consistent - if I was really sad I'd start making notes (but I'm not that sad - not quite anyway).

 

[KillerHERTZ]

making notes

You can borrow mine