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MD2040C Oil Pressure Sensor

Ammonite

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7 Feb 2007
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681
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Does anyone know if the factory fitted 0-10 Bar oil pressure sender on the MD2040c (part no. 366906) is an isolated earth variety ie. one pin for earth and one for the gauge or whether the two pins are for the gauge (G) and warning light (WK) and its earthed through the 1/8NPT thread? The Volvo part with two pin moulded plug is £114 but if I chop the plug off and fit two ring terminals I can buy one for about a 10th of this and just need to know what type the original one is. The same part is used on several Volvo models. Thanks
 

GaryCottam

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My MD2020B, I do not think is an isolated earth, it earths through the engine block. Mine has just one wire attached.

Someone with more knowledge than me should be able to confirm this.
 

Ammonite

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681
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My MD2020B, I do not think is an isolated earth, it earths through the engine block. Mine has just one wire attached.

Someone with more knowledge than me should be able to confirm this.
Mine definitely has two wires. I just dont know if its G and Earth, or G and WK. The seperate oil pressure switch has one wire but its the sender that supplies the optional vdo oil pressure gauge that I'm looking to replace

Its no.20 in this schematic
Volvo Penta Exploded view / schematic Electrical System MD2040-C, MD2040-D - MarinePartsEurope.com
 

VicS

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13 Jul 2002
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45,944
Mine definitely has two wires. I just dont know if its G and Earth, or G and WK. The seperate oil pressure switch has one wire but its the sender that supplies the optional vdo oil pressure gauge that I'm looking to replace

Its no.20 in this schematic
Volvo Penta Exploded view / schematic Electrical System MD2040-C, MD2040-D - MarinePartsEurope.com
The wiring diagram in your owners manual shows gauge sensors and warning light switches as separate items.

The pressure gauge sensor has a light blue wire going to the gauge, the warning light switch has a white/blue wire going to the warning light.

If your sensor has two wires I would expect the second wire to be a black wire and to be the earth connection
What are the colours of your wiring ................................... Its all volvo green I suppose :(

1617821702458.png
 

Kinsale373

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15 Jan 2017
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Kinsale Irl
I have a 2040. I just looked at the workshop manual and it shows the Senders with one pin going to the Instrument Panel and the other brought to Battery Negative via a fuse block . It specs the Sender as a Variable resistor
2 Bar equates to 52 Ohm
6 Bar equates to 124 Ohm
So any sender in this range should work.
The Pressure switch is shown wired the same with two connections , one to a designated input on the Instrument panel and the other to battery negative through the fuse block.
Regards Kinsale 373
 

VicS

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13 Jul 2002
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45,944
I have a 2040. I just looked at the workshop manual and it shows the Senders with one pin going to the Instrument Panel and the other brought to Battery Negative via a fuse block . It specs the Sender as a Variable resistor
2 Bar equates to 52 Ohm
6 Bar equates to 124 Ohm
So any sender in this range should work.
The Pressure switch is shown wired the same with two connections , one to a designated input on the Instrument panel and the other to battery negative through the fuse block.
Regards Kinsale 373
That sounds like the earliest ( A) version of the engine , which pre- dated engine saildrive isolation, and has an isolated electrical system .

1617829095604.png
 

Ammonite

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Location
Southampton
The wiring diagram in your owners manual shows gauge sensors and warning light switches as separate items.

The pressure gauge sensor has a light blue wire going to the gauge, the warning light switch has a white/blue wire going to the warning light.

If your sensor has two wires I would expect the second wire to be a black wire and to be the earth connection
What are the colours of your wiring ................................... Its all volvo green I suppose :(

View attachment 113024
Thanks VicS. The warning light has a white/blue wire. The pressure gauge sensor has two black wires which would have had a moulded two pin plug on it at some point which has been cut off and bodged with a couple bullet connectors that don't connect properly which is why I'm wanting to replace it. Alternatively the two black wires might be an extension of the original so I'll take a closer look at this. However if you are right about one of the pins being an earth then I should hopefully be beable to go with this assuming the white/blue feeds the warning light on the panel rather than a WK pin on the pressure gauge which I can easily check?

Perkins 4.108 Oil pressure sender
 

VicS

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Joined
13 Jul 2002
Messages
45,944
If things have been bodged in the past or if parts are not original VP parts it's difficult to be certain without checking it all out

I've seen no mention of a "WK" terminal in any of the wiring schematics I've looked at. Where are you seeing that?

I have found that a combined gauge sensor and warning light switch was fitted to the MD22 engines but that has three connections . A light blue , a white/blue and a black.
 

Ammonite

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7 Feb 2007
Messages
681
Location
Southampton
If things have been bodged in the past or if parts are not original VP parts it's difficult to be certain without checking it all out

I've seen no mention of a "WK" terminal in any of the wiring schematics I've looked at. Where are you seeing that?

I have found that a combined gauge sensor and warning light switch was fitted to the MD22 engines but that has three connections . A light blue , a white/blue and a black.
I was under the impression that a two wire sensor is either going to be an isolated type with gauge (G) and earth terminals or a non isolated version with gauge and warning light (WK). The sensor fitted to my MD2040c is the original two pin 366906 but it has no markings and the wiring diagram only shows a single wire which presumably is G. So my question was whether the second terminal is an earth or a WK terminal, although it seems odd that neither is shown on the wiring diagram. At this stage I'm assuming that its an earth and that the warning light is linked to a seperate single wire oil pressure switch as shown in your diagram
 

Kinsale373

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Joined
15 Jan 2017
Messages
200
Location
Kinsale Irl
That sounds like the earliest ( A) version of the engine , which pre- dated engine saildrive isolation, and has an isolated electrical system .

View attachment 113032
Thats interestimg Vic, I've seen mention of the Isolated -Ve system using a relay but I could never figure out why they would do it. So the answer seems to be isolate the sail drive and keep your electrical system out of the contact with the water , is that correct?
Kinsale 373
 
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