Volvo Penta MD2030 Tacho dropping out

[DaddaTony]

I have owned my current boat for 4 years with a Volvo Penta MD2030 diesel and have had intermittent problem with the tacho dropping out and setting of the VDO Cockpit Panel Alarm. The problem mostly occurred reversing out of my pen, once in forward alarm settled.

Recently the alarm has been going off while normally motoring at which time the tacho needle always falls to zero. I decided to service the alternator having it fully overhauled and reinstalled. Voltage output is as OEM Spec.

The problem has remained with the alarm going off now on a daily basis when motor in use.

I have cleaned all connections and as a last ditch effort change all the connectors to satisfy myself it's not just a bad or dry connection, still no joy.

Does anyone have a plausible explanation or possible fix?

Thanks all in advance.

[billknny]

Do you have any other charging devices connected? Wind? Solar? They can raise the voltage at at the battery terminal above the alternator output voltage, and trigger exactly what you see, even though nothing is wrong.

[Dsanduril]

What is it about the 2030 and the tacho this week? Third poster with this problem.

There's another thread on the same topics you might want to peruse, although no definitive solution/resolution (yet).

[DaddaTony]

Yes l do a DC/DC Projecta charger also connection for the solar input.

https://www.projecta.com.au/dual-bat...ttery-chargers

Thanks for your input.

[DaddaTony]

It was the other thread that prompted me in that it was similar but not the same.

Cheers & Thanks.

[chrisr]

if it is any consolation, it's not just volvo...we have almost the identical problem with tacho on our port Yanmar 4JH2TE

tacho will read upon start up and for about an hour our so...then slowly over a period of 1-2 minutes the reading will fall back to zero and won't work again until engine next cold start.

it's not the sender...suspect faulty component inside tacho which vibration or current upsets.

pesky but we're getting used to it

cheers,

[DaddaTony]

Thanks Chrisr
Drives me batty with alarm shrieking. Doesn't stay on permanently sometimes 30 seconds then stops sometimes 3 seconds and it stops. If it stayed on all the time I'm sure I'd be able to get to then end of it.

I agree possible the tacho itself rather than the feed. Seriously thinking of replacing tacho completely and see where that leads.

OEM VP Tacho outrageously expensive.

Thnx.

[billknny]

Don't go replacing the tach, it's not the problem.

The fact that the tack AND the charge alarm both go haywire in this way at the same time means that the alternator field current is shutting off. This can be a failure of the voltage regulator, or an external charging source driving the battery terminal voltage above the alternator's voltage regulator set point. If you have an external regulator, it could also be a loose connection.

And if you DO decide you NEED to change the tach, there is not reason to use a VP OEM gauge. They are totally generic. Get a VDO or other brand. Unless you really need to little Volvo label on it for some reason.

[DaddaTony]

Thanks Billknny,

Can you suggest a work around the other inputs? Just added a few pics for whatever helps.

Cheers

[Pelican 2]

Five years ago, when I bought my current boat a Bavaria 36, with the md2030 saildrive unit and same tacho unit you describe. My tacho was doing the exact same thing. I checked my voltage output at several rev ranges and it remained above 13.6VDC even at idle. It never rose above 14.6VDC so the regulator was not the issue. I checked the voltage to the tacho, and although I am no expert on what voltage it should be, there was voltage and it rose slightly with the revs of the engine. I looked on other forums and found the issue was not an uncommon issue with the volvo engine panel. I bought a new Tacho from SVB (not cheap) and the issue disappeared as soon as this was fitted. It would pay to check your voltages but I have since seen this twice more on other boat Volvo panels and both times the tacho was at fault.

[belizesailor]

Originally Posted by DaddaTony

Thanks Chrisr
Drives me batty with alarm shrieking. Doesn't stay on permanently sometimes 30 seconds then stops sometimes 3 seconds and it stops. If it stayed on all the time I'm sure I'd be able to get to then end of it.

I agree possible the tacho itself rather than the feed. Seriously thinking of replacing tacho completely and see where that leads.

OEM VP Tacho outrageously expensive.

Thnx.

Likely nothing wrong with the tach.

Is the alternator externally regulated?

Were any changes made to your system shortly before this problem started?

[DaddaTony]

Thanks Pelican 2

That's were I'm at moment investigating a change out unit.

[DaddaTony]

Chrisr
The fault as said has always been there however I have been cruising full time so has occurred on a daily basis BUT it has become more often on reflection possibly since the Projecta DC unit was installed.

Cheers.