Tamd41p oil pressure gauge / sender

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jakew009

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After a nearly 2 year hiatus I fired my TAMD41P up today and everything looks good other than the oil pressure gauge is just pegged at 100% as soon as you turn the ignition on.

Before I start troubleshooting can someone tell me

- where it is on the engine
- what it’s resistance should be cold

I’m assuming at the moment it must be shorting to ground somehow?

I have also rebuilt the instrument panel so I could have wired it wrong, but I couldn’t spot anything immediately obvious
 
jakew009 said:
After a nearly 2 year hiatus I fired my TAMD41P up today and everything looks good other than the oil pressure gauge is just pegged at 100% as soon as you turn the ignition on.

Before I start troubleshooting can someone tell me

- where it is on the engine
- what it’s resistance should be cold

I’m assuming at the moment it must be shorting to ground somehow?

I have also rebuilt the instrument panel so I could have wired it wrong, but I couldn’t spot anything immediately obvious
Click to expand...
Resistance for Euro senders is 10-184 ohms
 
OK after a date with my multimeter I am fairly certain my sensor is dead

I think this thing is the water temperature sensor



And this thing is the oil pressure sensor


Water temperature sensor reading


Oil pressure sensor 🧐


The Volvo Penta doc I found says the water temp should read 134ohms at 60 Celsius and 38.5ohms at 100 so that seems sensible on a cold engine.

The oil pressure sensor on the other hand is 32 mega ohms 😳 and it should be 10 ohms at 0 bar and 124 ohms at 6 bar. So I’d say it’s buggered.

Now got to figure out how to get the bugger out without stripping off the heat exchanger and the oil cooler 🤞
 
jakew009 said:
OK after a date with my multimeter I am fairly certain my sensor is dead

I think this thing is the water temperature sensor

Click to expand...
Unusual place for a temp sender, it would typically be in the head or thermostat housing. Sure it's not the oil warning light ? Pull the plug off and short the wiring to test that theory.
jakew009 said:
And this thing is the oil pressure sensor
Click to expand...
Yes, that certainly looks like the oil pressure sender.
 
Water temp sender on a 41 is on the thermostat housing, there's 2, 1 is a temp warning switch and 1 is sender.
I seem to recall the one behind the alternator is the pressure sender, I made a tool to do it without taking anything off.
You can use much cheaper senders but have to add a ground wire but must be 1/8npt thread and euro resistance.
I'm talking 41a but doubt 41p uses anything different as the base block is the same.
I seem to recall the cheaper sender had different size across flats but I got away with the same tool.
 
PaulRainbow said:
Unusual place for a temp sender, it would typically be in the head or thermostat housing. Sure it's not the oil warning light ? Pull the plug off and short the wiring to test that theory.

Yes, that certainly looks like the oil pressure sender.
Click to expand...

If it’s not the temperature sensor my mind is utterly blown but I am now questioning myself. I am almost certain that thing is connected to the temperature gauge.
 
snowbird30ds said:
Water temp sender on a 41 is on the thermostat housing, there's 2, 1 is a temp warning switch and 1 is sender.
I seem to recall the one behind the alternator is the pressure sender, I made a tool to do it without taking anything off.
You can use much cheaper senders but have to add a ground wire but must be 1/8npt thread and euro resistance.
I'm talking 41a but doubt 41p uses anything different as the base block is the same.
I seem to recall the cheaper sender had different size across flats but I got away with the same tool.
Click to expand...

Thanks, but now I’m even more confused. If that things not a temperature sensor what the hell is it?

I don’t think they are Euro resistance either, this is some proprietary Volvo / VDO thing.
 
Ok now I think about it the first sensor would make much more sense if it was the oil pressure switch. It had continuity which would make sense because I measured it when the engine was stopped.
 
snowbird30ds said:
View attachment 196762
Not the best angle but temp sender is the shiny bit between raw water pump and 90 degree fitting, that rectangular lump is the thermostat housing.
There is another green temp switch hiding behind it.
Click to expand...

Yes agreed that is one of the water temp sensors.

If the shiny bit is the one for the water Temp Gauge (Celsius and Fahrenheit), is the other sensor hiding behind it for the water temp alarm (beeper & flashing red light on the panel)?

On my TAMD41, the alarm and light were going off now and then at the weekend when cruising but the gauge was showing 80deg as normal. I need to check both of them are working ok but I could only find the obvious one in your photo (the shiny bit). My access isn't as good as on your boat so I didn't see the other switch hiding away at the top above the thermostat housing.
 
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Pleinmont said:
Yes agreed that is one of the water temp sensors.

If the shiny bit is the one for the water Temp Gauge (Celsius and Fahrenheit), is the other sensor hiding behind it for the water temp alarm (beeper & flashing red light on the panel)?

On my TAMD41, the alarm and light were going off now and then at the weekend when cruising but the gauge was showing 80deg as normal. I need to check both of them are working ok but I could only find the obvious one in your photo (the shiny bit). My access isn't as good as on your boat so I didn't see the other switch hiding away at the top above the thermostat housing.
Click to expand...

Yeah either I’m going blind or on mine there is only one sensor on the thermostat housing
 
I'm heading down to my boat later to have a look. Hopefully i have two separate coolant temp sensors in the same places as Snowbird.

Otherwise I'll be joining you in the hunt for the other one!
 
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