Yanmar 3-Banger Gauges Read Zero

[Gone2long]

I'm an admittedly ignorant, new owner of sailboat boasting a 20 year old Yanmar, three cylinder, 27 horse power diesel. The diesel seems to run fine, and may have been rebuilt in the past.

However, both the temperature gauge and the oil gauge read zero at start up and after running for up to half an hour. Apparently, this is an electrical problem, and may be as simple as a blown fuse or two, but I do not know where to look for such an items and what they might look like on a 12 volt system.

Any advice, photos, or links would be greatly appreciated.

Regards to all,

G2L

[GordMay]

See posts 1 & 2 ➥ http://www.cruisersforum.com/forums/...sting-645.html

[DotDun]

Originally Posted by Gone2long

I'm an admittedly ignorant, new owner of sailboat boasting a 20 year old Yanmar, three cylinder, 27 horse power diesel. The diesel seems to run fine, and may have been rebuilt in the past.

However, both the temperature gauge and the oil gauge read zero at start up and after running for up to half an hour. Apparently, this is an electrical problem, and may be as simple as a blown fuse or two, but I do not know where to look for such an items and what they might look like on a 12 volt system.

Any advice, photos, or links would be greatly appreciated.

Regards to all,

G2L

Assuming you have 3GM30s, these engines don't have temp and oil pressure senders on them by default, meaning the PO *could have* changed the instrument panels with one including gauges, but never put the senders on the engine. The 3GM30 has temp and oil pressure switches on them that turn on the light and buzzer in the panel.

Or, it's a simple wiring/sender check to see why they are not working.

[roverhi]

The PO probably added the temp and pressure gauge. That would require changing out the senders for ones compatible with the gauges. Follow the trouble shooting guides above to find where the fault lies. PO on my boat installed a temp gauge which didn't work when I got the boat. Went back to the Yanmar senser and warning buzzer which has worked fine. Problem with gauges is they are worthless if not watched regularly. Unless they are easily visible from the helm, warning buzzers are more useful and probably engine savers when needed.

[Sinbad51]

I had a 2 banger yanmar in my previous boat that had a panel with full gauges.
It also had a small black circuit breaker switch on the panel that when tripped it killed the gauges. You may want to see if there is one your panel.

[papasan]

The purpose of the warning buzzer is to tell you if you have an emergency engine problem. The purpose of the gauges is to tell you if your engine is gradually developing an oil pressure or temperature issue.

[dohenyboy]

seeing that it is both gauges which do not operate, I would check the ground circuit first.

[CLady]

Chase down the wires coming out of the backs of the gauges to the engine. Check the connections at both ends as well as the hot and ground wires.

[Old Swampy]

It might also be useful to check that the gauges still work. You could disconnect them from positive connection at the control panel, but leave them connected to the sender units which provide ground connection. If you then apply 12 volts to each in turn (observe correct polarity) you should then observe meter deflections commensurate with what they are measuring. You would want to run the engine to see if proper deflections occur. If after warmup you find no deflections, you will be unable to tell whether the gauges or the senders are at fault. You can check the senders by measuring the resistance to ground (with wires to the panel meters removed). This resistance should change when the engine is running. You might check the meters by applying a small voltage briefly across each. Not more than a volt and a half. Observe correct polarity. This a go/no go test; no deflection implies a burnt out meter. A better test is to use an Electronic VOM (Volt Ohm Meter). No resistance implies an open circuit or burnt out meter.

[Gone2long]

Originally Posted by DotDun

Assuming you have 3GM30s, these engines don't have temp and oil pressure senders on them by default, meaning the PO *could have* changed the instrument panels with one including gauges, but never put the senders on the engine. The 3GM30 has temp and oil pressure switches on them that turn on the light and buzzer in the panel.

Or, it's a simple wiring/sender check to see why they are not working.

Sorry, don't know what a 3GM30 is. Engine is a Yanmar, 27hrp, 20yrs old or so. I'm sure that the engine panel is not the original, but can't get any advice on it since owner moved out of the country. Will try to trace the wires.

Thanks for the comment,

G2L

[Gone2long]

Originally Posted by roverhi

The PO probably added the temp and pressure gauge. That would require changing out the senders for ones compatible with the gauges. Follow the trouble shooting guides above to find where the fault lies. PO on my boat installed a temp gauge which didn't work when I got the boat. Went back to the Yanmar senser and warning buzzer which has worked fine. Problem with gauges is they are worthless if not watched regularly. Unless they are easily visible from the helm, warning buzzers are more useful and probably engine savers when needed.

The engine console has a warning buzzer and two lights - one for battery and one for oil pressure. They go on at start up, suggesting that they work, since both pressure and batt, would be low as the engine first turns over. As soon as the engine is running, the lights turn off, so I assume that means they work.

Problem, however, is that the warning lights always work, but the buzzer does not always go on at start up. Have no idea what that means.

On the positive side, since the warning lights go off underway, that should mean that they are operational and that although the gauges read zero, the engine oil pressure is probably ok. No?

Thanks for your help.

G2L

[Gone2long]

Originally Posted by GordMay

See posts 1 & 2 ➥ http://www.cruisersforum.com/forums/...sting-645.html

Will do,

Thanks,

G2L

[Gone2long]

Originally Posted by Old Swampy

It might also be useful to check that the gauges still work. You could disconnect them from positive connection at the control panel, but leave them connected to the sender units which provide ground connection. If you then apply 12 volts to each in turn (observe correct polarity) you should then observe meter deflections commensurate with what they are measuring. You would want to run the engine to see if proper deflections occur. If after warmup you find no deflections, you will be unable to tell whether the gauges or the senders are at fault. You can check the senders by measuring the resistance to ground (with wires to the panel meters removed). This resistance should change when the engine is running. You might check the meters by applying a small voltage briefly across each. Not more than a volt and a half. Observe correct polarity. This a go/no go test; no deflection implies a burnt out meter. A better test is to use an Electronic VOM (Volt Ohm Meter). No resistance implies an open circuit or burnt out meter.

Some of this is admittedly a bit over my head, but will read the background that Gord suggested, and hopefully, I will have the knowledge to pursue this further.

Thanks for the detailed reply, which I will no doubt consult again in the near future.

Regards,

G2L

[Wotname]

Originally Posted by Gone2long

Sorry, don't know what a 3GM30 is. Engine is a Yanmar, 27hrp, 20yrs old or so. I'm sure that the engine panel is not the original, but can't get any advice on it since owner moved out of the country. Will try to trace the wires.

Thanks for the comment,

G2L

A 3GM30 is a 3 cylinder Yanmar engine of 27 HP and they were popular 20 years ago and are still popular. There should be a name plate on the engine block with the model number on it but it might be hard to read.

Fair bet that you have a 3GM30 .

[Gone2long]

Originally Posted by Wotname

A 3GM30 is a 3 cylinder Yanmar engine of 27 HP and they were popular 20 years ago and are still popular. There should be a name plate on the engine block with the model number on it but it might be hard to read.

Fair bet that you have a 3GM30 .

That is exactly the kind of stuff I need to know. Truly appreciate your help.

G2L