Water temp sender location Volvo md2020

[calviclassic]

Evening
I'm fitting a water temp gauge to a Volvo md2020, (doesn't currently have one)
Unsure where the sender would go, I believe it's a 1/8 thread?

 

[han34]

When I fitted mine a few years ago it screwed in the port side of the heat exchanger, there was a blanked off threaded hole.

 

[calviclassic]

The only thing I can see on that side is the large drain plug which would be far too
big?

 

[VicS]

Just a word of caution

Some versions of this engine have an isolated negative return, ie do not use the cylinder block for the common negative connections.

If this is so the sensor will have to be a two wire type.. The clue will be if the other sensors are two wire. (The sensor for the high temperature alarm is screwed into the head not far from the above location)

The wiring for the temperature gauge sensor may already exist. If so its a light brown wire ( perhaps together with a black negative wire)

 

[VicS]

The only thing I can see on that side is the large drain plug which would be far too
big?

Is the sensor for the warning light and alarm fitted in the heat exchanger ? If so the position for the gauge sensor is in the head, tucked in above the alternator,

 

[han34]

Mine was definitely in the side of the heat exchanger, it was a surprising large thread and the wiring was already there.

 

[han34]

Just had a look at the workshop manual, page 66. It shows the senser in the side of the heat exchanger, as mine was. It shows the overheat alarm screwed into the head. It's possible the sensers replaced the relay on some models?

 

[calviclassic]

Thanks chaps, a closer look reveals two senders already fitted, one on the front of the engine twixt water pum and h e and another forward of first injector, single wire on each, brown and white & blue white striped wires respectively, the first (with much bigger thread) is for water temp alarm? If so I assume I need a two wire sensor of the same resistance to replace this with?

 

[VicS]

Thanks chaps, a closer look reveals two senders already fitted, one on the front of the engine twixt water pum and h e and another forward of first injector, single wire on each, brown and white & blue white striped wires respectively, the first (with much bigger thread) is for water temp alarm? If so I assume I need a two wire sensor of the same resistance to replace this with?

No.

Your engine then has a single wire system, not a two wire system ................ You do not tell us which version it is . It might save lot of guessing if you did.

The sensor with the brown and white striped wire is the coolant temperature switch, for the high temperature warning light and alarm as you suggest

The sensor with the blue and white striped wire is the oil pressure switch, for the low oil pressure warning light and alarm.

The sensor for the temperature gauge, if fitted, will have a single light brown wire.

( a sensor for an oil pressure gauge will have a single light brown wire)

You still need to find the location for the temperature gauge sensor........

 

[calviclassic]

Ok
I get the wiring now.. I have so far been unable to check but I think the large plug on the side of the heat exchanger I thought was a drain must be the location, 5-8 unf I believe

 

[han34]

Yes,. As I said, mine was on the side of the heat exchanger and the workshop manual shows it on the side of the heat exchanger.