Yanmar (VDO) tach/engine hrs

[Sailshabby]

I have one of those pesky LED engine hour gauges on my Yanmar that has died and tried the previously posted fix to no avail. I've picked up a DC powered Hobbs meter to remedy the situation and have a quick question on the connection. I assume the ground will go to GROUND (upper right connection), but it appears I have a two choices for the other - TACH SIGNAL or TACH/Hrs (see photo). Intuition tells me it's the latter, but that's the same intuition that gives me the winning lottery numbers, none of which have actually been winners. Same intuition tells me it could be either (a signal being a signal, and all that).

The photo appears to have TACH/Hrs as the... third from the left? Guidance, folks?

Thanks.

Shabby

[a64pilot]

I don't know anything about your current gauge, but you can wire your new Hobbs so that it's powered and therefore running whenever the ignition is on and not muck with your current tach wiring.
The low oil pressure warning horn keeps people from leaving ignition on, but engine off for more than a couple of seconds, so your Hobbs will be accurate.

[sgancarz]

In looking at the pic you have, third from the left is ignition 12V. The other 12V input is for lighting only.

[Charlie]

Just installed a mechanical Hobbs engine hour meter yesterday. Yanmar had the same problem. I don't know the exact hours since it went down. I am hooking mine up to the oil pressure sender. Good luck

[Sailshabby]

Thanks, my friends!

[Cheechako]

Just wire it to your key switch power. Key on/Hobbs on

[Sailshabby]

Preference is to actually track 'engine running' hours, Plus my engine installer saw fit to drop the Yanmar panel in that saves me the trouble of using a key. The oodles of extra wiring probably baffled him.

[a64pilot]

You have some form of switch that you turn on to enable the starter, don't you?
When this switch is on, the low oil pressure alarm is on?


A "true" Hobbs install is leave Hobbs powered when ignition is hot, ground wire is connected to an oil pressure switch so that whenever there is oil pressure, the circuit is completed and the Hobbs runs whenever there is oil pressure, assumption of course being that the only time there is oil pressure is when the engine is running

Most of us have some form of "ignition switch" that when this switch is on, the low oil pressure alarm is sounding, seeing as how I've never met anyone that will just let that alarm go off without it annoying them, it's a safe bet that whenever the ignition is on, there is oil pressure and its OK for the Hobbs to be triggered just by ignition voltage, without an oil pressure switch, cause that alarm is not going to allow you to forget to turn off the ignition, whether it be a switch or a key.

[BruceS]

Yes it seems like most just record one hour as .... one hour.
Most heavy machinery record hours "at operating revs".
For instance if a bulldozer operates at 1800 rpm then it will record one hour at that revs but at idle .... 900rpm it will only record half an hour for the one hour it's idling.
Maybe that's what that other terminal is for?

[ramalkin]

You can buy a replacement LCD display here
https://vdo-webshop.nl/en/displays/2...achometer.html

[epoxyman]

Charlie
You wrote in your response - you connect to the oil pressure sender - did you mean oil pressure SENSOR or the oil pressure meter/alarm or the Oil low pressure switch????
Thanks

[sailormed]

Just yesterday Daydreamer41 posted on SBO about the succesfull installation of the below mentioned LCD display in a Yanmar instrument panel.

SBO link https://forums.sailboatowners.com/in...4#post-1526660

EBay item https://www.ebay.com/itm/LCD-Display...MAAOSwn6dbbR2S

I think I will order this part for my 3JH4E. Finally a solution!

[epoxyman]

My problem (4JH4E with C Type instrument panel) is that I cannot get to the back of the panel so I must connect my (+) lead from the hour meter to a wire that goes hot with the on switch. This wire must be accessible near the engine - does anyone have a suggestion???

[pandw]

Followed Daydreamer41's post on SBO, plus the video on Youtube, and my Yanmar tach hour-meter now works perfectly again, and shows the original hours. A great solution and actually pretty straight forward, once you get the darn thing out of the tight space its mounted in.

SBO link https://forums.sailboatowners.com/in...4#post-1526660

https://www.youtube.com/watch?v=eldRUU7qc2Y

To be clear, I replaced the LCD with a new one from ebay. See SBO link. The Youtube video is just to show you how to tach the tach apart. The repair in the video (removing the silicon on the LCD ribbon) is proven to not last.