3YM30 Tacho sender thread size?

[DevoDave]

I want to install a magnetic tachometer sender in the thread on the bell housing at the rear on the exhaust side of my 3YM30.

I don't want to use the tacho signal out of my Balmar Alternator/regulator combo as the signal disappears when batts are full.

Anyhoo, does anyone have data on the thread size? I have pulled the bolt and the thread looks to be 11/16 inch with my cheapo micrometer but I would expect the Japanese would have made it metric so I'm seeking confirmation.

[Wotname]

The QM, GM and 4JH series use an M18x1.5 thread (metric fine).
The Yanmar part number is 128170-91160 (ex 124070 - 91160), the VDO number used to be 340.804/007/007.

I'm certain it will be the same for 3YM30.

[GordMay]

I suspect Wotname is correct, as usual.

Page 9-41 of this “4JH Series” Manual indicates “M-18 x P1.5"
➥ http://sagaforumet.com/yanmar-manual...kapittel_9.pdf

The 3YM30 Shop Manual doesn’t indicate an MPU thread size, but the oil & water senders use the M-18 x P1.5 thread.
➥ https://j109.org/docs/yanmar_3ym-2ym-service-manual.pdf

[DevoDave]

Cheers guys. I've ordered an M18 x P1.5 and will report back when it arrives.

[DevoDave]

I can confirm M18 x p1.5 is the thread size.

I just need to sculpt the signal now to feed my tacho and it's all good.

[Wotname]

^^

[DevoDave]

To save me physically (mis)counting the teeth, does anyone know how many teeth are on the 3YM30 flywheel?

[DevoDave]

I have determined that the flywheel on my 3YM30's has 97 teeth. This may be useful to others.

Now sucessfully running with a M18 thread magnetic pickup screwed into the bell housing, into an EMU-1 NMEA2K interface, and connected to a Faria 32803 magnetic-pickup type tacho. Digitally accurate NMEA2K tacho! Sweet.

[NevilleMills]

I’m very interested in this thread as since fitting Belmar 618 reg as part of lithium install the tacos play up when batteries are full. Thinking of fitting flywheel sensors to both motors in my fusion 40 but need to know if they will drive original do Yanmar tacos and how to wire them up to do so. Can anyone help?

[sainted]

Originally Posted by DevoDave

I have determined that the flywheel on my 3YM30's has 97 teeth. This may be useful to others.

Now sucessfully running with a M18 thread magnetic pickup screwed into the bell housing, into an EMU-1 NMEA2K interface, and connected to a Faria 32803 magnetic-pickup type tacho. Digitally accurate NMEA2K tacho! Sweet.

DevoDave, did you use Yanmar’s sensor or a sensor from another supplier?

Scott

[DevoDave]

Scott, I used just cheapo ebay sensors. AU$20 or so each.

[DevoDave]

Originally Posted by NevilleMills

I’m very interested in this thread as since fitting Belmar 618 reg as part of lithium install the tacos play up when batteries are full. Thinking of fitting flywheel sensors to both motors in my fusion 40 but need to know if they will drive original do Yanmar tacos and how to wire them up to do so. Can anyone help?

If your Yanmar tachos are alternator-driven then they won't work with a magnetic pickup. I changed to Faria magnetic-pickup tachos.

[sainted]

Devo, one more question: are you driving the Faria tach directly from the sensor, or are you filtering it through the emu-1?

Scott

[DevoDave]

Originally Posted by sainted

Devo, one more question: are you driving the Faria tach directly from the sensor, or are you filtering it through the emu-1?

Scott

The output from the mag-pickup is paralled between the EMU-1 and the Faria's. Both work fine for me although I did need to stay with an older version of EMU-1 firmware as newer versions struggle to lock on to the signal. I'm confident if you run just the tachos it would be rock-solid.