Vetus M4.5 coolant temperature sensor?

[Rivelin]

Hi all,

 

Is the horizontal device (with a bolt head, next to the hose) in attached photo a coolant temperature sensor? I ask because the small black wire to earth is no longer attached and the temp. gauge is showing zero, so I'm wondering if this is related?

 

Many thanks!

[WotEver]

I’d think it more likely that it’s the thingy with the blue wire attached, but that’s only a guess. I have no idea what that black wire is for although it appears to have broken off the back of that chrome thing. 

[Craig Shelley]

The blue wire is the over heat switch. It sounds an alarm on the panel if the engine gets too hot. The manual describes how to test it.

Vetus don't usually provide engine temperature gauges on these engines, which I think is a bit ridiculous.

The bolt next to the hose is the logical place to install a temperature sensor, with the appropriate thread adaptor. It looks like someone has already installed a sensor on your engine. The bolt on the top with the blue lug crimp is being used to provide the 0V reference for the gauge. That bolt is actually a coolant air bleed, which supposed to be removed when filling the coolant for the first time to avoid getting air lock.

The wire is obviously missing from your sensor. I would say the stud appears to be broken off the sensor too.

As there is no provision for engine temperature sensor in the engine harness, we have cable tired our wires to the hose in order to provide a strain relief.

My guess is that someone installed the temperature sensor onto this engine, but didn't adequately provide a strain relief on the cable. The cable has at some point been snagged, and ripped the stud out of the sensor.

[Rivelin]

Since I posted the original message I have found a snapped off white cable roughly attached to a bunch of other cables, which is hanging below this sensor.  Certainly corroborates your description.

 

Many thanks for your detailed reply - now I know I don't need to worry about the damaged sensor as there is an overheat switch (which I'll test).

 

Edited September 26, 2019 by nickhindle