I have a 2000 W-reg E430 estate. It has been very reliable and well-maintained. It is now with me in southern Spain and, even though it is very hot here with very steep hills, the car has never overheated and the temperature normally remains around 90C.

However, two days ago, while returning up the hill from the coast (sea level to 850 metres) I noticed that the temperature gauge had whizzed up to 120C. I had already stopped at my home in the hills so I opened the bonnet and noticed that the small near-side fan on the outside of the radiator was turning.

I drove the car to the coast and back up the hills yesterday. Again it reached over 100C so I pulled over, left the engine on and opened the bonnet. The main fan was working but not as quickly as I expected.

At no point did any red warning lights on the dashboard indicate illuminate - something that surprises me considering the amount of sensors and warnings that Mercedes normally given for everything from low water in screenwash to a brake light being faulty.

I am nervous about using the local Mercedes dealership since they have a terrible reputation for taking your money and not doing anything. And since we will not return to the UK for another 2 months I obviously need to do something about this problem.

Please give me the benefit of your experience/knowledge if you can.

Thanks,

Joe

 

BTW
I have just checked the handbook and it states the following:
"The boiling point of the coolant in the pressurised cooling system will be approximately 130C if antifreeze/anti-corrosion additive is present in the correct concentration. It is permissible for the coolant temperature to climb to the red mark at high outside temperatures and when driving in the mountains."

I had the car serviced by a non-Mercedes garage just before coming to Spain a month ago. I wonder if the answer is that he did not put in the correct ration/type of anti-freeze? Would that make this difference? As I said, the car has been driven in these hilly and hot conditions for over a year and the temperature gauge has never exceeded 100C.

 

Hi Joe, how many km on your engine?
Your problem could be weak fan clutch. Check it by turning the fan propeller in the morning with cold engine. You should be feeling good amount of resistance almost like a magnet trying to spring it back. Also you may have one or two electric fans on your radiator. One for A/C climatization and other for safety against overheating. Check them too. If the same coolant was in the engine when it was working fine and no one changed it or add any water into the system, mixture should be fine.

 

Hi, thanks for the reply.
Around 216,000 km. Runs like a dream. Never seems to use oil or water and apart from this and one or two other ****les, is one of the best cars I have had.
There is some resistance, but it's difficult to get the engine totally cold since the ambient temperature in the morning here in southern Spain is around 25 degrees C at the least in the mornings.

I have noticed that the belt connecting the electric fans has come off! It is somewhat twisted but not snapped. Will I be able to put it back on if it has come off? That is, it presumably came off for a reason to do with wear...

I can order one from the UK, since my wife is returning to Spain on the weekend and can bring it with her. Are they easy to fit? Is there anywhere with instructions and diagrams that you could recommend.

I am assuming that the belt is the problem since the car overheats when I am travelling slowly up steep hills in hot weather.

Thanks again for the speed of your reply.

 

Slipping cooling fan belt could be your only problem. There should be way to apply tension on it to stretch it and prevent it from twisting and slipping. Have your wife pick it up and bring it to Spain. Shouldn't be problem for you to change it or take it to any local mechanic and since you will have the belt, it should be just the labor and they will replace it while you wait for it.

 

if the 2 fans in the front of the radiator are not working you still should not overheat. the other fan behind the radiator is for engine cooling. the 2 fans in the front are A/C system related.

 

Thanks for comment. Since posting I have loosened the front fan assembly and discovered a rolled-up fan belt in the corner of the compartment. Having refitted, both front fan belts work when using the AC and they also both operate when the temperature exceeds 90 degrees C.

You may well be right that the viscuous fan or something else is faulty and that the secondary AC fan is not the only problem, but it does seem odd that the overheating happened at the same time as the front fan belt came off. No?

I have ordered the part (order number A0119970092) from Mercedes in Dorchester UK (£10.98 inc. VAT) and my wife will bring it out with her this weekend.

The old fan belt was not snapped and, though it was bent and twisted, I was able to temporarily fit it back in place and test the car.

I will keep you informed if this solves the problem when driving in the heat of the day up the 850 metres from the coast.

 

The tension should keep it running streight and spin both fans when demanded. Your temperature gauge should start declind when ever these fans kick in. Your main fan viscous clutch is probably still fine, keeping engine cool by itself when you driving around the sea cost.

 

Thanks for that. I will test drive it up the hills in the heat of the day (up to 40 degrees C) to ensure that the problem is solved.