e300td overheating

[mercury]

engine overheated when towing up steep hill resuting in loss of coolant. mechanical fan ok but two electric fans not working. anyone else experienced this?
i have not located the sensor or control unit yet but i think the sensor is in the engine block and the control unit is under the left front wing. managed to drive back home (300miles) by keeping to 45mph and avoiding hills with use of the heater when necessary to reduce temperature.

 

[television]

It is the oil cooler that is under the wing the thermostat opens at 85c and on then then coolant flows.

The Aux fan is controlled by the N65 control unit; and that is fed from the in car control unit.

I think that I would check the visco clutch at 90C and see if the fan chops up a carrot

 

[wireman]

Perhaps your thermostat is on its way out, if its as old as the car there is a chance that it is getting tired or that some scale has built up within your cooling system especialy around the stat.

Failing to adhere to the 2 year (or whatever life is stated on the can) antifreeze change rule can result in this behaviour on any vehicle. Antifreeze contains chemical protection against corrosion and scale which degrades long before the non freeze part does.

Flush and replace the stat and antifreeze.

 

[bouncer]

Just looking on the Bosal tow bar web site and it says "Not for 300TD with air conditioning and/or stationary heating"
So they dont recomend a tow bar for this vehicle.

sTeVe

 

[mercury]

overheated

I think we have a misunderstanding of the problem. The thermostat and the main fan are ok and normal driving is ok but when hard pressed ie steep hill with caravan attached and/or air conditioning operational then the auxilliary electric driven fans should operate and they are failing to cut in and hence the temperature rises to 120c and loss of power results. The RAC man that came to my rescue and supplied me with water was unable to diagnose the fault and rectfy it. The fault first occurred near St Austel on a steep hill.I drove to Tewkesbury carefully and fortunately parked my caravan next to a former AA breakdown mechanic who was very helpful but also unable to solve the problem . My son suggested that there is probably a temperature sensor that can be shorted out using a paper clip as he had done this on a Rover that he used to own but I could not locate one. I decided to drive back to Lancashire slowly and investigate further. Hence the question on this forum. If in doubt do nowt is my motto so I am keeping my tools in the box until I have a little more knowledge.

 

[mercury]

the tow bar on my car is original mercedes fitted unit as standard

 

[Number_Cruncher]

The temperature sensor is under the intake manifold towards the rear of the engine. It's a lot of work to remove it just to check the sensor.

If you want to check it without removing the manifold, there should be a plug where the engine wiring harness connects to the vehicle wiring harness, and you would be bal eto probe there.

What I can't help you with is pin identification or wiring colour, as my data are for the OM606 as fitted to W124s. Perhaps someone with access to the wiring diagrams for your model will be able to find the pinouts for you.

 

[television]

With the checking that I have don,,there is not one on the engine,,or I have not found it yet, it is operated by the Air con and not the engine as far as I can see

 

[Number_Cruncher]

That's surprising Malcolm.

The (well hidden) sensor on the W124 serves both the dashboard temperature pointer and the electric fans - the fans may also be activated by high refrigerant pressure by the switch mounted near the receiver/dryer. I would be surprised if this logic had been abondoned for W210s.

 

[television]

That's surprising Malcolm.

The (well hidden) sensor on the W124 serves both the dashboard temperature pointer and the electric fans - the fans may also be activated by high refrigerant pressure by the switch mounted near the receiver/dryer. I would be surprised if this logic had been abondoned for W210s.

I know the system with the 124 where it is on the top front of the engine,but the wiring on this on goes from the fan to the control box for the fan,and this is controlled from the air con unit in the dash.

It takes ages searching the diagrams and I went as far as I could within the time span