Engine Tachometer

[rxc]

Hi there. I just changed engine oil and coolant, and now my tachometer doesn't work. The sequence was: (1) drain and refill coolant, (2) start engine and warm up oil (during which time, the tach worked fine), (3) stop engine, change oil and filter and transmission oil, (4) restart engine, which runs fine, but now the tach is not working.

I noticed that the hour meter is working fine. I finally found the tach sendor on the engine (aft, port side almost under the turbo), and it does not look like I bumped it or disturbed the connectors. I also looked at the wiring harness connectors that are right in this same area, and I don't think I dripped any coolant on them. They are well attached, and pretty clean.

Anyone have any other thoughts?

Thanks in advance.

Ralph Caruso
s/v Petillant, just about ready to head north for the summer...

[cm]

Hi Ralph

My tacho goes to 5000rpm and the hour meter packs up when my batteries are fully charged. Yanmar and my sparkie said this sometimes happens. Now I want a replacement under warranty and Yanmar are denying it is anything to do with them. They also say the warranty doesn't cover any instruments because they are made by VDO. Nearly as bad as a Jeanneau warranty!

CM

[rxc]

CM,

First an update: my tach problem has become sporadic. Occasionally, when I start the engine, I get it to indicate speed. Sometimes, however, it does not move off of zero. I plan to engage my dear wife in a loose connection hunt next week, which she is sure to love - her sitting in the cockpit watching a gage that doesn't move while I shout out "Did that change anything?!" about 50 times...

I had a problem similar to yours on my old C34, after I had installed a high-output alternator and a Link 2000R regulator/controller. When the batteries were full, the regulator would shut down the field current to the alternator COMPLETELY, and the alternator output would drop to zero, because the tach used alternator ripple to determine speed, not a sensor on the engine. But my tach read zero, and did not go to the high end stop. Also, the hourmeter did not move when the alternator stopped working.

I eventually learned to start up some big load in the boat to drop the battery voltage and get the regulator to kick in. Alternatively, just turn on your running lights - they usually draw enough current to keep the alternator working.

Ralph