tachometer

[bristol321]

Hello all,
Has or does anyone use an alternator tachometer. Where the pickup/sending unit is attached (I've heard tapped) into the alternator.

If so have you found it relatively user friendly? Brand? Longevity etc?

[artbyjody]

Originally Posted by bristol321

Hello all,
Has or does anyone use an alternator tachometer. Where the pickup/sending unit is attached (I've heard tapped) into the alternator.

If so have you found it relatively user friendly? Brand? Longevity etc?

If you have the documentation for your motor it is usually described in the schematics diagrams...Fairly easy to do and the typical off-the shelf parts will do the trick...

[Maine Sail]

Most diesel engines pull the sense off the tach. You'll need to get the right tach for use with your particular alternator. Usually a quick call to the engine manufacturer will send you in the right tachometer direction. The actual act of calibration may be the tough part unless you own a photo electric tachometer. You can pick up a photo electric tach from Eastwood for about $90.00. Although it is possible you that may find one elsewhere cheaper I trust and purchased mine there because they are a great company to deal with.

Photo Electric Tachometer

[pegasus1457]

Photo tachometer -- I found one on ebay for $27 (shipping included). It is a Chinese import (what isn't), but seems to work. Can't test it on the boat diesel yet. It is still winterized and on the hard.

[Valiente]

One advantage of the alternator tach I discovered the hard way. I have a freshwater cooled diesel and the alternator and the freshwater pump are run off the same belt. When going back and forth from the pump out dock, I noticed the tach reading flipping around a bit. Then it seemed to stick. Then I noticed the engine temp was 230 F.

Yes, I replaced the belt that had split longitudinally and wasn't turning the freshwater pump much. Now I know that if the tach wobbles...check the damn belt!