'87 300 E overheating
 

From what I have seen, this seems to be a common problem on this model.
Please advise what my next step should be. The car quickly gets to 120C and will even whistle from being too hot.
Replaced the thermostat today, idled it in the driveway to see if this solved the problem. Within 5 minutes, it was up to 120C again.
What should I do next? Radiator cap?
The electric fan did kick in~ isn't enough to keep the temp down:(

replace the fan clutch,it's probably freewheeling and not locking up.

Well, since the electric fan isn't cutting it either (and I assume it will do it on the road, where the fans no longer matter), I would be suspicious of the radiator either plugged internally OR the outside is full of dirt, bugs, leaves, etc keeping the air flow from passing through the radiator, OR the AC condensor plugged up, again leaves or dirt or whatever keeping air from flowing through. More than likely internal to the radiator though, what's the coolant condition, been flush/replaced/serviced lately? I'd start by pulling the radiator and inspecting the outside and then you can see the condensor pretty well, if all looks fine then get it to a radiator shop for checking.

Gilly

Yeah if its getting that hot even when going 50-70 down the road its a problem other than the fans....at those speeds the fan isn't really doing anything.

Just for the sake of completeness, you may want to check the water pump weep hole to be sure the water pump is still pushing enough water through the system (and not failing) or that you're not leaking any fluid.

Overheating update
 

Well, I have had the cooling system flushed (it was pretty ugly stuff) and replaced the radiator cap.
Sprung a leak in the lower radiator hose, wil try to get that changed tomorrow. Car was still overheating AFTER the flush *before the leak*.
Where is the water pump weep hole? Top? Drivers? Passengers?
Thanks for helping out on this!:confused:

Either you have a blockage or your water pump is not working at all.

Since you have had the system flushed. Try turning on the heater and see if that makes a difference. If it does not there could be that there is no circulation which could indicate a water pump failure.

Water leaking out of the water pump outlet does not indicate a total failure of the pump - rather a bearing failure.

If your auxillary fan is not cutting in that this does not indicate a sensor failure for this.

Are you sure that your water temperature gauge is indicating correctly?

As already mentioned above. The fans are irrelevant when cruising at 50 Mph or even Kph.

I am reasonably sure the guage is accurate, or at least close. The car has gotten so hot that it whistles ..... Since I don't want to have to replace a head gasket too I have parked it until this is resolved.
Blockage or water pump at this point....??....
Too much on the calendar already for this week, will post again when I have more info.
Thanks again for the feedback!:cool:

If you just replaced the thermo, then you may have an air lock.

Park on a hill incline , remove the cap , run the engine and slowly squeeze the top hose with gloves on to burp the system.

Unclamp the hose at the water pump. Start the car (briefly). If water forcefully shoots out, your pump is working. If it doesn't, it is not.