W124 300TE 24 overheating

[BlueQuinn]

What likely causes are there for my car to overheat? I'll tell the whole tale in case anything is a clue.

I came off the motorway where the customary 80 degrees showed on the temp gauge and into a traffic jam, where it got hotter. This I expected, but then the needle kept rising into the red and sure enough lots of steam and fairly new Comma red coolant escaped.

After waiting for it to cool I poured 3 litres of expensive spring water into the header tank and went on my way, taking a circuituous route to keep moving and keep air coming through the grille. I made it the next 20 miles thank goodness. Needle staying at 80 when moving, but creeping up when stuck in traffic. It stayed below 100 after that

So what's going to be wrong?
Fan broken? Thermostat gone? Waterways furred up?
It's done 208000 miles and between 124000 and 136000 it had both radiators, thermostat housing, coolant level sensor and water pump replaced
Last coolant change in January.
Last MoT a week ago I was shown a small coolant leak from somewhere. Barely noticeable.

 

[brucemillar]

It does sound like a fan issue as the engine is cooling correctly when moving.

 

[kth286]

you mention newish coolant.

You may have an airlock in the circuit.

 

[BlueQuinn]

After it's MoT there are a couple of issues I need to get sorted, so I'll book it in for a service with Automerc. Might as well get the system pressure tested, flushed and refilled and the thermostat and fan tested/replaced.

 

[millo777]

Sounds like fubar fan clutch. If you let the car get up 100c, you should hear the fan click in as the clutch engages. Alternatively, you can test it by sticking a rolled up newspaper into the fan blades when the car is at 100c. If it's workign properly, it should rip the newspaper to shreads. If it's broke, the newspaper will stop the fan spinning.

You also mention new red coolant, which may also be the cause of the problem. If you've mixed OAT coolant with some remaining blue or green IAT coolant left in the system, this can create a sludge that impedes the water flow.

Thermostat is very unlikely to be the issue as they fail in the open position, so a broken stat would mean the car would take longer to warm up, but shouldn't cause over heating.

On that engine, I would also consider a block test to see if the head gasket is o.k, just to be sure.

 

[grober]

Almost certainly a malfunctioning viscous fan coupling.
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[kth286]

The thing is; the fan is hardly ever needed in the UK and especially at this time of year.

With a properly operating cooling system, you should be able to leave the car idling all day and the fan should not cut in - I can with mine.

The fan is only there for 'extremis' ie. very hot uphill slow moving traffic or towing/heavily loaded etc.

 

[WDB124066]

kth286, what happens is the VC loses the ability to transmit much torque at all when disengaged, the fan pumps almost no air at all. The fan is supposed to pump a fair quantity of air through the system even when not engaged.

 

[kth286]

kth286, The fan is supposed to pump a fair quantity of air through the system even when not engaged.

Don't think that's the case.

The key to an efficient system is the pump pushing the coolant through the radiator (which is exposed to cooler air).

If there is an airlock in the cooling system from a recent coolant change,
then the system will not be working properly.

 

[WDB124066]

I KNOW it is the case.

 

[kth286]

I KNOW it is the case.

You can remove the fan from UK cars and it will not make hardly any
difference most of the time.

 

[grober]

I would adopt a pragmatic approach- Renewing a water pump is invasive- involving draining the cooling system- removing the pump etc - replacing the viscous fan coupling is relatively simple. I would try the newspaper/carrot test to see if the fan engaging--- if not ------try replacing the viscous coupling first and see if that cures the problem.

 

[WDB124066]

Next time you swap one out hold your hand above and slightly forward of the fan, on both VC's, then you will notice the difference in the quantity of air being shifted at idle disengaged. Very important feature in hot, stop, go traffic conditions. Not as important on the highway or open road - until you slow down.
Here is some first hand experience; 28 Deg C ambient, 100 - 110 km/h open road motoring, speed limit drops to 70 km/h temp rises from 85 to approx 98, all other conditions being equal. Took it to the mechanic, he held his hand out over the rad, fan and front of engine area and closed his eyes, I thought he was in a trance saying a little prayer; he was testing the fan airflow. All we did was to change the fan VC, and only the fan VC, problem gone.


To the OP make sure your engine mount cooling system is in place [if originally speced], it may also help keep underbonnet temps down when working the car really hard.

 

[Vlad]

I've just replaced a Fan Clutch on a W124 E220 that was getting hot sitting in traffic last week. New fan clutch and all is well again. Purchased from Euro Car Parts.

 

[BlueQuinn]

Further investigations, now that I've had time - When I start the car the fan spins for a moment, then stops. At one point it looked like it was trying to move so I gave it a nudge and then it kept turning, though not fast.

This was with a cold engine as I don't wish to run it too much with just natural spring water in the cooling system

I don't suppose this helps rule the viscous coupling in or out does it?

 

[grober]

No its another indicator its probably had it.[ lost fluid] My fan always ran quite quickly on engine start up. It could be easily stopped by the newspaper or carrot test when cold but you were always conscious of working against slight fluid drag wanting it to turn

 

[davidjpowell]

The thing is; the fan is hardly ever needed in the UK and especially at this time of year.

With a properly operating cooling system, you should be able to leave the car idling all day and the fan should not cut in - I can with mine.

The fan is only there for 'extremis' ie. very hot uphill slow moving traffic or towing/heavily loaded etc.

Had a dealer tell me this while waiting for a new warranty part on a W203 C320 cdi. I then ended up in a slow uphill moving traffic jam. Result was a flatbed collecting my car and a hire car being dropped off while in a hotel on a course.

 

[balge]

The (electric) fan on my 230TE only ever cuts in under some provocation, very slow traffic and a properly hot day...

Viscous clutch on the 300TD drags a bit at tick over when cold but destroys newspapers quite happily when you give it some revs

Oh btw - if the bottled water was 'mineral water' it may be worth flushing it - those minerals are mainly salts and you don't want them in the system

 

[kth286]

I've just replaced a Fan Clutch on a W124 E220 that was getting hot sitting in traffic last week. New fan clutch and all is well again. Purchased from Euro Car Parts.

Martin

I would suggest all that has done is mask a poorly performing cooling system.

The pump etc etc are just not performing as they should be.

There should not be any overheating problems in this weather.

 

[BlueQuinn]

The (electric) fan on my 230TE only ever cuts in under some provocation, very slow traffic and a properly hot day...

Viscous clutch on the 300TD drags a bit at tick over when cold but destroys newspapers quite happily when you give it some revs

Oh btw - if the bottled water was 'mineral water' it may be worth flushing it - those minerals are mainly salts and you don't want them in the system

Too right. It was an emergency measure to get me home only. It will do to get me to the garage too and I'll have them flush the system