Tach on H33 - 2QM15

[dwgifford]

I have a 1978 H33 w/the 2QM15 diesel and the tach on the engine control panel seems to read low. After reading posts on this site I see rpm's of 2200 - 2500 rpm's on these engines. The manual says it develops full hp at 3000 rpm/s. Mine runs great and at 1800 rpm indicated I have done 6.5kts by GPS. In neutral it max's out at about 2100-2200 rpm. Is there a problem with my tach or sensor or what?

 

[Ed Schenck]

Yep, something is amiss. My old 2QM20 had to turn around 2800 to make 6+ knots. In neutral it would easily run 3000. I cannot remember the tool that the Yanmar mechanic uses to adjust. It is a handheld tach that attaches to the alternator I think. Probably something cheap from Autozone would work.

P.S. Here is something that might help: http://www.tunelab-world.com/rpmsound.html .

 

[Ken1686]

I have a 1980 Hunter 33 with a 2QM15 engine that has the Yanmar tach. I have noticed over the years that the indicator needle for the tach sticks at initial engine startup. I have had to tap the tach's glass dial face and the needle jumps about 200 rpm and then settles down for a normal tach reading