Oil gauge issues

[jimbunyard]

You raise a good point (one that I've been through similarly as well). It might be a step in the right direction to test the resistance at the sender and then reconnect the sender wire and check the resistance at the connection to the gauge to see if they match, (if that hasn't already been suggested)...

[a64pilot]

Originally Posted by wingssail

So I guess tomorrow when I go to the shops looking for a low oil pressure switch and a mechanical gauge I'll take a sample and make sure the threads match perfectly. I don't want to change the threads on my engine and leave a hidden problem for the next guy.

Take the sender with you. A sender operates a gauge, a switch operates a light or a buzzer. It’s likely you have both, but sometimes both are built into one device. Usually a sender is larger than a switch.

I tried unsuccessfully to find a BSP to NPT adapter. I found one and ordered it but it was way too small.

[a64pilot]

You may end up replacing the gauge in the panel either with a Yanmar gauge , or if it’s a 2” gauge, with one that looks as close to factory as you can find. I’ve seen 2” and 2/1/16” gauge, but I believe those are actually the same, one referencing the diameter of the gauge and the other the size of the hole, I have also seen 1.5” gauges.

You could even network the gauge on a NMEA 2000 network and display in on your plotter.
Last boat I did that, but the motor was a Can-Bus and it was easy to integrate everthing.

[CassidyNZ]

I must say, response from Yanmar was pretty prompt. The parent company got hold of the agent in Auckland who got hold of the agent in Opua who contacted me within 24hrs of my original enquiry. Impressive. But was the solution as impressive?

Turns out there appears to be both Euro and US options in sender/gauge matching (low ohms v high ohms). The Opua agent located a genuine gauge that matches my panel in Australia that apparently also matches the new sender I bought. It would seem this situation must have been like that since initial installation. One has to wonder why the owner at the time never made a song-and-dance about it.

Be that as it may, the cost of the new gauge is $380. However, now that I know that the gauge works back-to-front but in doing so still reflects a correct reading, I can’t see why it shouldn’t stay that way. I’m not sure I want to spend another bunch of money on it.

Thanks for input gents. Whilst the idiosyncrasy remains, my doubts as to its validity have been allayed and now I just have to win a small Lotto to decide whether to fix it.

[Wotname]

Originally Posted by CassidyNZ

I must say, response from Yanmar was pretty prompt. The parent company got hold of the agent in Auckland who got hold of the agent in Opua who contacted me within 24hrs of my original enquiry. Impressive. But was the solution as impressive?

Turns out there appears to be both Euro and US options in sender/gauge matching (low ohms v high ohms). The Opua agent located a genuine gauge that matches my panel in Australia that apparently also matches the new sender I bought. It would seem this situation must have been like that since initial installation. One has to wonder why the owner at the time never made a song-and-dance about it.

Be that as it may, the cost of the new gauge is $380. However, now that I know that the gauge works back-to-front but in doing so still reflects a correct reading, I can’t see why it shouldn’t stay that way. I’m not sure I want to spend another bunch of money on it.

Thanks for input gents. Whilst the idiosyncrasy remains, my doubts as to its validity have been allayed and now I just have to win a small Lotto to decide whether to fix it.

That is an impressive response time. It is good to know real why the gauge worked the way it did.

I guess we will never know how it came to be that the sender and gauge never matched.

I would spectate the owner at the time never really looked at the gauge and when he did, he just saw the pointer sitting mid scale and thought "yep, that's good". If he installed the engine himself, he just assumed it must work that way - Yanmar wouldn't get it wrong! If it was installed by a Yanmar agent, maybe they just didn't care.

Clearly someone, somewhere at sometime screwed up but who, where and when remains undiscoverable.

If you are like me, you would like to be right but would I spend the money - I dunno!

I would likely test the gauge with a potentiometer (described upthread) to get a baseline of what the gauge needs and go searching for an aftermarket sender the matches the gauge and probably available for less than $100. Partly because I'm cheap like that but mostly because I don't support Yanmar's overpricing on parts policy.

Yanmar will not have made the various senders, they will be using some already available senders. Your job is to find which one .

[Jwhit]

After a fair bit of searching I believe the Oil Pressure Sender, the Oil Pressure Alarm Switch, and perhaps other fittings are 1/8 BSPT: 0.907mm pitch, 9.728mm outer diameter and tapered.

British Standard Pipe Tapered.

https://www.britishmetrics.com/image...spp_bspt_4.htm

Adapters available on McMaster-Carr

[wingssail]

Originally Posted by Jwhit

After a fair bit of searching I believe the Oil Pressure Sender, the Oil Pressure Alarm Switch, and perhaps other fittings are 1/8 BSPT: 0.907mm pitch, 9.728mm outer diameter and tapered.

British Standard Pipe Tapered.

https://www.britishmetrics.com/image...spp_bspt_4.htm

Adapters available on McMaster-Carr

Here is the adaptor I purchased.