Date registered: Aug 2009
Vehicle: '72 250C, '74 280C, '85 500SEL, '81 300CD.
Location: Tucson, Az.
Mentioned: 2 Post(s)
Quoted: 49 Post(s)
The vacuum modulator is located on the lower transmission housing. Follow the vacuum piping from the intake manifold.
Which temperature switch are you attempting to replace? I believe the 1972 models use a manual gauge for the temperature gauge. The other senders are for choke, timing advance and a 100C cooling fan relay.
Easy test for the cooling fan. With the ignition in the "run" position, ground the wire from the connector to the engine. The electric fan should engage. This connector is usually a "bullet" style connector.
The sending unit you are showing is the "bayonet" style which is more commonly used for the choke/timing/idle relays. If there are numbers imprinted on the new sender such as 100C, 65C, etc., then it is for activation of a circuit and not a variable resistance type of sending unit used in temperature gauges.
Last edited by Mike D; 07-03-2016 at 05:37 AM.