removing coolant level sensor - PeachParts Mercedes-Benz Forum

jsmith · #1 07-15-2002, 09:53 PM

my car started exhibiting the phantom low coolant light syndrome i've seen discussed before. coolant level and temps are ok so i'm thinking maybe the sensor is dirty or shot. i'll try disconnecting it tomorrow, in the meantime, maybe someone can tell me how it goes in the overflow tank - does it screw in?

Ken300D · #2 07-15-2002, 10:32 PM

I'm going to guess your overflow tank and sensor are similar to the ones I've seen on both '87 and '92 300D cars. The sensor connector is on the engine side of the tank and has two mammoth pins.

When I got my '87 300D, I found the sensor disconnected and of course the light would never come on. I wanted the sensor to work since it is highly important on an aluminum head car, so I plugged it back in. This resulted in phantom light actuation.

I kept plugging and unplugging the thing and cleaning the connections - now it works fine as far as I know.

So if you are getting phantom indications, try cleaning the electrical plug connection on the side of the overflow tank.

Might help in your case too.

Ken300D

jsmith · #3 07-15-2002, 11:14 PM

yes, i looked for the terminals right away and they are kinda dirty. i'll give that a shot tomorrow. did you say there are two pins that hold the sensor in place?

pmizell · #4 07-15-2002, 11:55 PM

Joe:

The sensor is held on by one big "circlip" that has two holes at each end. Take a pair of needlenose pliers and work it off. Once that is off it will slide right out. A rubber O-ring will come out with it also, so look out for it while yanking it out.

Good luck!

~Paul

______________________
'91 300E, 215K miles

Mike Richards · #5 07-16-2002, 05:43 PM

I coated mine with some clear silicone based lube - just a bit. I then used an 18mm deep socket to gently tap it in. This was done as part of an expansion tank replacement. New tanks do not come with coolant level sensors installed.

jsmith · #6 07-17-2002, 02:15 PM

the terminals were encrusted and i had a hard time getting the connector off. once i unplugged it i cleaned the terminals with a soft wire brush and fine sandpaper for good measure. i sprayed a little wd40 on it and plugged it back in and the light stayed off.