280sl overheating problem

[Intex]

I just got my car back from putting in new wiring loom and fuel pump, drove it off from the repair shop and 15 minutes later the temp gauge is in the high side. When I stop at a light it starts to heat up higher, then goes back down when the car is running.

Any ideas where I should begin my search for the problem?
Clogged radiator?

The car had been sitting for 3 years.

[Garry]

A good professional chemical flush of the whole cooling system would be a good start and see if the radiator survives the test otherwise it may be a recore of the radiator.

Garry

[Peter van Es]

Check the viscous coupling of the fan first...

Peter

[athadani]

Had a similiar problem and after trying all the recommendations, had a new gasket installed for the engine block. Have been problem free since then.

Good luck

Ashok
280SL US model - 1970

[Paul & Dolly]

As Peter says, the fan coupling  is the place to start,
and relatively easy to check.
You have shown that air flow (when the car is in motion) is providing some cooling, so start with the fansystem.


Good luck
Paul.

[Intex]

When you say to check the fan coupling, are you looking for the fan to be spinning, or not?
What are you looking for?

[WRe]

Hi,
the visco clutch is always one of the first points to look after but also incrustation (scaled with calcium ) of the whole system (our cars are very old).
I personally made very good experiences with cleaning of the system with citric acid as shown in old MB workshop manuals or here: http://www.w126.kistinger.com/Kuehlsystem_reinigen.htm.
First drain your coolant and flushing it sometimes with clear water, then fill it with a mixture of water plus 10% citric acid (ca. 1.5 kg; cheap in vinicultural shops), drive around a little bit (heating must be on; thermostat open) to mix it in the whole system and leave it there for some hours. When you drain it should be brown if it was successful. After that you should flush it again sometimes with clear water before you fill it with freeze coolant. I always use rain water.
...WRe

[Rolf-Dieter ✝︎]

I had a similar problem. My friend a knowledgeable mechanic checked my fan operation (as others have mentioned). He checked the operation of the Fan Clutch (small fan inside the main fan) as I was parked, pushed on the gas in neutral and then shifted into gear (simulating a stop at the traffic light). He determined the problem to be the fan clutch. I ordered a new fan clutch The Benz DR. installed it with his boys and the problem was solved.

I recommend you have someone check your fan clutch operation. Perhaps it is the same issue.

[GGR]

You can check the fan clutch by rolling a newspaper and trying to stop the fan with it while the engine is hot and idling. If you can stop the fan then the clutch needs replacement. Some people have been successful by refilling the clutch with wax. I've never done it but you will find the info on the net.

[WRe]

Hi,
- information about a visco clutch you will find here: http://www.kfz-tech.de/Engl/Viskoluefter.htm
- restorationn here http://www.buschtaxi.org/cms/index.php?id=479.
...WRe

[Garry]

Just to get back to the original post, this car has been sitting for three years and presumable driven at least a year or two before that and yes the fan clutch needs to be checked but you need to flush the system and replace the coolant that will be next to useless before you start driving it around as it most probably will be full of scale and gunk.