Good morning, I have a 1993 300E with 159,000 miles on it. For the last couple of day the coolant light would come on and flash then go off. This morning it came on and stayed on. It's less than two mile from my house to the office. Engine had not even warmed up yet when the light came on.

Suggestions as to what I should check and do would be greatly appreciated.

Overheated in Alabama
Jeff

Check the coolant level in the coolant expansion tank. If the fliuid is below the level sensor then add coolant ... and check for the source of a leak. If the coolant level is fine then perhaps the level sensor is bad and needs replacing.

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Fred Hoelzle

Yes you need to determine if the coolant is low. That sensor is basically a float and plugs into the side of the over flow tank.

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Auto Zentral Ltd.

The car is new to me and I don't have a parts book with diagrams, therfore I took a photo and hope that someone can help.

I found two plastic bottles with water in them under the hood. One is labled #1 and the other is #2, on my photo. The #1 bottle seems to have an electrical connections attached to a plastic part which can be removed. If any one can please tell me which one does what, and if I have found the float which controls the panel light.
Also if I were to disconnect the small electrical connector would the light on the panel go out. Of course this is assuming that I am talking about the correct tank.

Be educated in Alabama
Jeff

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No. 1 is the screenwash resevoir, no. 2 is the coolant expansion tank.

The expansion tank seems to be full of that nasty green stuff. Drain and replace with Zerex G05 or MB antifreeze.

The coolant tank sensor is in the side of the tank closest to the engine towards the bottom (I think - don't have my car here to check).

Welcome to the world of MB - that M104 should last almost forever if taken care of.

The coolant expansion tank looks kind of full to me. Maybe a fault with the connection to the sensor or the sensor itself.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Thanks Guys, for the repy; I disconnected the electrical connector on the bottom of the expansion tank nearest the engine block as stated and the dash light went out.
New question, does it take a special tool to remove the float/sensor to install a new one.
Also is this type of sensor one which you can do a capcity check on to see if its good or bad.

Thanks,
BeachGuy

You need a pair of snap ring pliers. If the light went out, the sensor is defective so just replace it. Don't try to figure it out. I've tried. It is a stupid little float, and you can't see why it doesn't work, but it doesn't. It's a cheap part so just do it. I've given up wasting time on the dumb things. I'm sure some EE here is going to accept this challenge and spend hours on research, but I have better things to do.

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Auto Zentral Ltd.

Thanks for the help, no ready to order the part.

BeachGuy

I replaced mine in August. The access to the coolant level float is improved by removing the top section of the air filter box. Snap ring piers are necessary to remove the snap ring that holds the sensor to the reservoir. Don't remember if an 'O' ring is involved, probably is, so best to inquire when ordering the sensor. With 10% MBCA discount, the sensor cost about $30 if I remember correctly.
regards,
Mark