Volvo Penta oil pressure sender Ohm Range?

Mr Googler

Mr Googler

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Hi all

Does anyone know the ohm range sent by Volvo Penta oil pressure sender?

I have bought a couple of Chinese specials digital oil pressure gauges.

It came with a single pole sender which will fit no problem but I need insulated return (so 2 wires). Huge thanks to volvopaul for explaining that to me!

Standard automotive is 10-180ohm for 0-10bar. Got the multimeter out and the supplied sender does indeed have a resistance of 10ohms at 0 psi. I tried the same on the volvo sender and it appeared to be the same. With the engine running and at 58 psi on the gauge, I seemed to get 186 ohms. Tricky to tell as the multimeter was a bit hit and miss.

Needless to say, the new gauge powers up fine but reads 0 psi so a new sender is needed however....lots of stuff I read says vdo is 10-180ohms?? Then there’s talk about the ohms scale being used in reverse too. 3-233 ohms. Ended up confused so anyone in the know on all things ohms and gauges :)
 
no idea,

did you remove the VP sender, cleaned it carefully and read the numbers on it?
Is it VDO (looks like in most engines the senders are vdo...)? if it is, with a little search you should find what it is and what you should be getting.
You'll also get an idea of the thread... Most on my IVECOs the TwinDisk box and the yanmar are M10X1 fwiw. Good thing is that you can find nice cheap sensors in China :D

how did you get the 186Ω btw? you're not meant to have the gauge connected when testing if values are to have any meaning me thinks!

good luck!

V
 
vas said:
no idea,

did you remove the VP sender, cleaned it carefully and read the numbers on it?
Is it VDO (looks like in most engines the senders are vdo...)? if it is, with a little search you should find what it is and what you should be getting.
You'll also get an idea of the thread... Most on my IVECOs the TwinDisk box and the yanmar are M10X1 fwiw. Good thing is that you can find nice cheap sensors in China :D

how did you get the 186Ω btw? you're not meant to have the gauge connected when testing if values are to have any meaning me thinks!

good luck!

V
Click to expand...

Not sure on the ohm thing. It’s a self calibrating thing so moves the decimals about....might have been 18.6 ohm :)

I took the wires out the back of the gauge and went between signal and 12v neg with the probes.

Never thought to check my manuals! Answer is in there as below.

B6FFE2D3-5FD5-4998-AF40-53BBB0BDE9A9.jpg

Should work then...as long as the gauge is the standard 10-180ohms. Can’t figure out why it’s not....email sent to China. I’m not hopeful :):):)
 
Last edited:
well, sender looks VDO allright...
of course with a quirky socket so that VP can charge more :D

single/vs twin station does make a difference, maybe the wiring to the gauge if single should be different on the new gauge?
tried the other engine? same thing?

play with the wiring is my only suggestion, or hope that the reply you'll get will make sense and not simply thank you for your purchase and ask you to return the gauges for a full refund...
 
I don't understand why your Chinese gauges can't use their own single connection senders. The negative will simply be the boats -VE, assuming the engine is connected to -VE.
 
superheat6k said:
I don't understand why your Chinese gauges can't use their own single connection senders. The negative will simply be the boats -VE, assuming the engine is connected to -VE.
Click to expand...

That’s the issue.

Volvo Penta are isolated earth so the engine block is not connected to -ve.

Volvopaul explained it to me as I was very lost!
 
I went through this when I had AD41's, In the end I bought matched sets of sender and gauge from a UK ebay car parts supplier for about £20-£30 each. I may have bought a thread adapter for the sender to but it was a while back on a previous boat so that might have been for an after market water temp gauge. Anyway they worked fine.
 
dpb said:
I went through this when I had AD41's, In the end I bought matched sets of sender and gauge from a UK ebay car parts supplier for about £20-£30 each. I may have bought a thread adapter for the sender to but it was a while back on a previous boat so that might have been for an after market water temp gauge. Anyway they worked fine.
Click to expand...

Was the sender a 2 wire isolated earth?

I’m thinking of buying a “universal” isolated earth sender and trying that. No word from China yet :)
 
a pic of the gauge would be nice with wiring instructions (if they make any sense in CN...)

I'm thinking that now you're wiring the lot in a way that defies the VP V- isolation logic.
I mean your CN gauge will need V- V+ and the signal from the sender. I assume lighting is going to be on when engine is on else there's another cable for lighting the gauge.
All that does is getting the block connected to V-, or have I got that wrong?
 
vas said:
a pic of the gauge would be nice with wiring instructions (if they make any sense in CN...)

I'm thinking that now you're wiring the lot in a way that defies the VP V- isolation logic.
I mean your CN gauge will need V- V+ and the signal from the sender. I assume lighting is going to be on when engine is on else there's another cable for lighting the gauge.
All that does is getting the block connected to V-, or have I got that wrong?
Click to expand...

2'' 52MM Universal Digital LED PSI Car Oil Press Pressure Meter Gauge 7 Color https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/382736559891

No instructions as such.

3 wires in the new gauge
Red ve+
Black ve -
Green signal from sender

Current gauge
Blue brown ve +
Black ve -
Light blue signal from sender

Another ve + and - for the gauge bulb.

On the volvo sender light blue and black wires
 
FARSCO said:
Was the sender a 2 wire isolated earth?

I’m thinking of buying a “universal” isolated earth sender and trying that. No word from China yet :)
Click to expand...

You have got me thinking now.
I definately replaced sender and gauge on both engines but it may well have been water temp. (I spent a few weeks fiddling with both and it was 4 years ago)
The oil sender was two wire for sure.
I will check my records and get back if I find anything usefull.
Sorry for the possible mis guidance..
 
Not at all...any help appreciated.

I’m still trying to find out the ohm range of the gauge. Need an ohm generator.

Buying cheap Chinese stops me getting bored :)
 
FARSCO said:
Not at all...any help appreciated.

I’m still trying to find out the ohm range of the gauge. Need an ohm generator.

Buying cheap Chinese stops me getting bored :)
Click to expand...

:D

not ohm generator, variable resistor is what you need, or a volume potentiometer from your local electronics shop, should be a quid or so, just get the smaller range one as they typically are 5-10KOhm and it's not going to be good.

V.
 
vas said:
:D

not ohm generator, variable resistor is what you need, or a volume potentiometer from your local electronics shop, should be a quid or so, just get the smaller range one as they typically are 5-10KOhm and it's not going to be good.
V.
Click to expand...
Cheers Vas. Bought these

5 Pack - Thumb Adjust Variable Resistors - Potentiometer, Preset, Trimmer, Pot https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/290932635909

I bought the 460 ohm ones. They’ll be 4 spare if you want them :)

So....get the gauge, connect + and - to a battery.

Connect green signal wire to the variable resistor and another wire to battery negative.

Connect meter measuring ohms to each side of the variable resistor so I can see what the resistance is?

Watch the gauge and figure out what the ohm range is for 0 to 150psi.

Is that the way to do it?
 
Not quite, I would suggest you connect up as you say minus the meter, adjust the pot until you see say 150psi or whatever value pressure you want then disconnect one wire going to the pot then connect the meter to measure the resistance. Not good to try to measure resistance whilst it is still in circuit.
 
Ok...this getting wierd!

Been playing with the gauge.

If I connect up to the loom ve-....no psi reading

If I connect ve- to the ve- busbar near by....reads perfectly!

When I connect up the oe gauge to the normal loom....it works fine.

If I connect the ve- to a different ve- location....will I knacker anything, run the risk of a short? All my battery ve- are joined
 
Presumably there is a reason why Volvo did not earth the block ( galvanic corrosion etc)

Galvanic corrosion seems part science prt art form so whilst I would do this on a car I would be more wary on a boat!
 
That’s where I’m getting confused J.

All my batt ve- are joined as is common practice.

I’m using the isolated oe sender. The gauge measures resistance to ground from the sender. All grounds lead back to the batt ve- (avoiding the engine block of course) so by picking up another ground source....I don’t think im creating an issue.

I’m wondering if there is resistance in the loom wiring/ connectors (highly possible) and the digital gauge is more sensitive. What’s weird though is if I put my meter between the sender signal and loom ve-.....I get nothing but when using busbar ve-....I get resistance as expected. The oe gauge however works with loom wiring!

I dunno. I’ve yet to have a run so will see if the digital gauge reads correctly when full hot...on plane....tickover etc....
 
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