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123 Chassis Water temp sender

Submitted by marybeth on 29 March 2007 - 1:23pm.
1985 MB 300D 123 Chassis Diesel. Dead Water temp guage looking for water temp sender ? I see three place for Senders for water temp guage #1 on the Engine block (drivers side) #2 on Water housing (passenger side) #3 On water housing (on front of engine) 1) Which sender feeds the instrument temp guage? 2) Can I check to see if the problem is guage or sender by grounding the wire goiing to the sender ? (will the needle on the guage move?)
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The temp gauge sending unit

30 March 2007 - 9:23am
rockcrawler
Actually there are four temperature sending units on that car (assuming '85 300D turbo, federal model). There is one in the thermostat housing (horizontal), one vertical near the thermostat, and two on the left side of the cylinder head. The temp gauge sending unit is located on the left side of the cylinder head, next to the injection pump. There are two senders in that location, both mounted horizontally. The gauge sending unit is closer to the firewall. I suppose that if you ground the sending unit connector, the gauge should go to the full hot position. I suspect that the sending unit is the problem. Gauges do not fail very often. I have proved this to myself on many other vehicles.