Running hot (ish)

[Ade W124]

91 300CE 24V on 53k

Just returned from a round trip to N.Yorkshire via Manchester and South Cheshire - car ran without a hitch except..

I notice the temp is around 80 under normal driving but will slowly climb to 110 in traffic (AC was off) - today's external temp in London was showing 19-20 so I'm thinking a little preventitive maintenance is in order before the summer kicks in. It doesn't appear to be losing coolant and the car has curiously only one electric fan at the front...

From reading other posts I have not heard the aux fan kick in... so I'm assuming the following course of action:

1. Run the car to temp and try the 'carrot' test on viscous fan.
2. Change coolant and replace with decent stuff and correct mix.
3. Change thermostat subject to results of 1 & 2.
4. Change viscous fan coupling subject to results of 1.
5. Change water pump if all the above fail..

Any other thoughts on this - I've got a digital volt meter somewhere which I can prod at various electrical bits with guidance...

Ade :???:

 

[television]

Ade some 124 have a electric clutch fan, others have the visco. If there are two wires coming out of the top its electric.

You need to be sure of the one that you have as electric fans cut in at 100 and visco 80c

 

[Bolide]

I'd say it was a weak viscous fan or a sludged-up radiator

Nick Froome
www.w124.co.uk

 

[Ade W124]

cheers for prompt replies (as always)

will have a poke round tomorrow - the coolant is pretty clean (although a funny beige colour) and the rest of the car seems in reasonable nick and has a fmbsh albeit with an intermittant 7 year lay off..

what colour should MB coolant be?

Ta Ade

 

[television]

OK so you do have two fans,I was not sure in your first post, so do the carrot test when the engine is at 80c, the electric one should cut in at 100c

 

[Ade W124]

I was referring to the fan in front of the rad - most M104's I've seen have 2 fans here - I think...

Will update results

Ade

 

[television]

I was referring to the fan in front of the rad - most M104's I've seen have 2 fans here - I think...

Will update results

Ade

I do not think that my 1990 300TE had two, yours is the updated model over what I had back in 1991

 

[Bolide]

You only have the additional electric fans if you have a/c

Nick Froome
www.w124.co.uk

 

[wscheffer]

You only have the additional electric fans if you have a/c

Nick Froome
www.w124.co.uk

That's correct and I belive the Aux fan will only turn on when the A/C is running.

 

[television]

That's correct and I belive the Aux fan will only turn on when the A/C is running.

Not all the time though as I can recall.

 

[Ade W124]

Can't seem to simulate the problem in the driveway with a closed bonnet....

Needle will ease up to somewhere around 90 and sits there at tickover (around 750rpm is this a bit low?) A constant throttle at around 2k cools it down again - which would seem to suggest that the fan is working.... A/C activation makes no difference although something A/C related is making a noise under the bonnet (another minor niggle to look into at some point).

Couldn't get the aux fan to kick in..

Will drive the car around a bit (got to get some carrots as we ate the last of our stock last night... ) and pop in to local MB dealer to pick up some coolant and have another look... Is this simply a case of long motorway drive, into stop start London traffic for an hour or so?

Think I'll drain and flush the system anyway as the existing coolant is probably well past its best.

Ade

 

[Ade W124]

Well the engine bay is now covered in bits of shredded carrot which would appear to rule out a lazy viscous fan...

car hovered around 100c in S London traffic, cooling to 90 underway - picked up some official MB antifreeze and will drain the system at the weekend as its back to work tomorrow..

can't seem to get the aux fan to kick in with the AC on.. - any fuses I should check?

At least the AC seems to be blowing cold, and it looks clean and shiny on the outside .

Ade

 

[television]

As I said earlier the electric fans do not cut in until 100c you could always check the sensor by shorting to ground

 

[Ade W124]

Quick update on this - car is still running hot with AC in traffic after coolant change.

Spoke with previous owner on this and he reckoned the car has always run hot in traffic with the AC on.

He seems to think that the car had AC fitted at the dealer before registration (ie. its not a factory fitted one) which would account for the single electric fan at the front of the AC rad.

Would it be reasonable to fit a S/H double fan unit to the front from a similar W124? If so anyone any idea of how to do it.

I'm going to pick up a thermostat this weekend from MB in anycase and replace this to see if it makes any difference.

Bit annoying that I can't use the AC on a hot day.....

Ade

 

[Ade W124]

think this is what I need

Got a quote from MB parts today when I ordered a new thermostat. Euro car parts a lot cheaper..

Anyone attempted installing these instead of the single AC fan I have

Alternatively could I just fit another 'general purpose' electric fan.

Either way it looks like I'll have to relocate the horns, existing AC fan and the pipe at the front which disappears back below the RHS of the engine (whatever it is?)

Any comments appreciated.
Ade

 

[eyelight]

Installed a new thermostat on our E280 recently. Got it from Mercedes dealer for about £13.50. GSF have then for about £8.

Our car had an overheating problem similar to yours. New thermostat seems to have cured it, but haven't had much chance to drive it all week so I'll reserve judgement until I do a few more trips into London. I know I'll be needing a new viscous coupling anyway, as my fan is always on.

I have the two electric fans in front of the rad, but curiously one of them is missing a blade and one of my horns has a piece of plastic knocked off. Something (maybe a bird) must have hit there at speed and someone just replaced the grill. Rarely use the a/c so haven't noticed if these two fans work or not.

 

[Ade W124]

Well replaced the thermostat today - one of the most straightforward bits of car maintenance I've encountered in a long time - hands didn't even get dirty

Car now runs at around 80 at tickover and a smidge below 100 in traffic with AC on- which is a 10 degree improvement & based on what I've read on here and the other forum, seems about ok...

The inside of the thermostat housing looked nice and clean and the old thermostat looked new (unlike the crusty thing in the haynes manual)..

Hopefully no more anxious needle watching..

Just need to regass the AC and then sort cosmetic bits in the near future..

Thanks for the helpful comments.

Ade

 

[d215yq]

Am I being stupid here but I seem to be having a bit of trouble reading the temp gauge in my w124 e220.

When the car is driven even in light traffic the temperature gauge will stay at 80 (maybe a very slight bit more if driving up steep gradients).

In traffic (particularly when being held on the brake in drive) it can quickly rise so the gauge is horizontal, where it stops and never rises above the point where it is exactly horizontal. What temperature is this horizontal and, if it never rises above there can I continue to drive it like this without risking any damage to the engine?

Cheers,

Ben

 

[vijilants]

91 300CE 24V on 53k

Just returned from a round trip to N.Yorkshire via Manchester and South Cheshire - car ran without a hitch except..

I notice the temp is around 80 under normal driving but will slowly climb to 110 in traffic (AC was off) - today's external temp in London was showing 19-20 so I'm thinking a little preventitive maintenance is in order before the summer kicks in. It doesn't appear to be losing coolant and the car has curiously only one electric fan at the front...

From reading other posts I have not heard the aux fan kick in... so I'm assuming the following course of action:

1. Run the car to temp and try the 'carrot' test on viscous fan.
2. Change coolant and replace with decent stuff and correct mix.
3. Change thermostat subject to results of 1 & 2.
4. Change viscous fan coupling subject to results of 1.
5. Change water pump if all the above fail..

Any other thoughts on this - I've got a digital volt meter somewhere which I can prod at various electrical bits with guidance...

Ade :???:

Re your step 2, not much point in getting the proper stuff until you have eliminated the water pump and thermostat.

Or else you will be wasting your new antifreeze mix when you go to replace these items.


Oops....prior to posting this I didn't realise that the thermostat sorted it )