Tachometer issues on 39 DS

[mmgriffith365]

Hi,

We have had the boat two years and just returned from eight days of cruising the gulf coast of Fl. We had to motor the last three hours (no wind) back to our home port. We were running at 2800 RPM. Two and half hours into the motor, the tachometer started to give crazy high and then no readings. The engine remained constant and showed no signs of a problem. has anyone experienced this? Is it strictly a gauge issue or should we be looking for something else? Our mechanic is on vacation and we don't want to use it and risk damage. Has anyone else had this experience? Thanks!

[MalcolmP]

Yes almost certainly a gauge/wiring issue. I had the same on our 39i 2008 due to water dripping onto the loom connectors below the exhaust elbow.

I would check there for any sign of leaks and give those connectors a spray of water displacing lube /WD40

The following 2 threads give more info

jeanneau.proboards.com/thread/2700/engine-wiring-harness


and

jeanneau.proboards.com/thread/2765/42ds-yanmar-exhaust-mixing-elbow

should help - coincidently (or maybe not) my engine hour meter has just packed up

[svsecco]

My 39DS exhibited the same symptoms. The wiring harness chafed through on the aft port engine mount. the dealer replaced the harness under warranty. the replacement was straightforward and did not appear to be too difficult. you might be able to splice the wires together if the damage is not too bad.

[mmgriffith365]

Thanks so much for the responses! We will follow your lead and look at wiring and connections.