[:@] I've checked th relay it's good. The original fan temp switch turn on the fan as soon as you turned the key i changed it. I got 2 temp switches from a junk yard I've tried both now the fan doesn't come on at all even when the temp goes over 107 any body got any answers

 

I think you should buy a NEW fan switch. I have taken many of the MB devices and switches apart, and when they are old they are just shot and you can't rely on them. You can test the fan switch by connecting a volt-meter or 12v test light to it, and dipping it in boiling water. It should quickly switch on or off...every time, not just 6 out of ten times. You can also run a pair of small jumper wires directly to the fan to see if the fan motor is seized-up.

 

Thanks BLUE for the info
Fan motor not seized, check this out I put the original temp switch back in this time the fan didn't come on when I turned the key. I let the car idle, when the temp got to about 100 the fan kick on so I took the car for a 10 min. drive. When I got back the fan was off I let it idle again and the temp went between 100 and 120 this time no fan. I drove it again and came back still no fan, I let it idle again temp went to 100 and fan came on and stayed on. I turn the car off let it cool completely down went back about 4 hours later turn the key and fan didn't come on but I didn't let the car get to temp to see if fan kicked on again.

 

Did you "burp" the air out of the cylinder head at the thermostadt cover?

Sometimes you'll get a large air-pocket trapped in the head that can keep your coolant sensor from actually touching the coolant. You have to bleed that air out. An air pocket can also make your temp gauge malfuntion... You can try loosening the sensor slightly with the engine running, until coolant begins to seep out, then close it back tight. But there should be a coolant bleeder screw on top of your themostadt cap for that purpose.

 

Check the temp rating inscribed on the sensor. You can have sensors that trigger the aux fan at 72, 85 0r 100 deg C.
If you want your fan to come on at a lower temp, use the sensor with a lower temp rating.
Please get a new OEM sensor for proper functioning. It is not that expensive.
Shan.

 

Thank for the info

Yes I did bleed the system that day maybe that was it I didn't drive the car yesterday but will today I'll let you know what happened. I was wondering do you know anything about cool start problems I changed the injector and fixed the wires going to it because it was bad in one spot (cracked & touching) but it still seems to start ruff but not as bad as before and not as often.

Thanks again

1986 190e 2.3