Tachometer problems

[tahomathundr]

Has anyone had a problem with the Tach reading 700-1000RPM too high. I fired up the engine last weekend and the tach read 1450 RPM at idle and went off the scale at cruising speed. The engine was not matching the rev's of the tach, thank goodness! I own C309 #20 "Big Luv" here in Seattle and this is the first time the tach has acted up. Any Ideas? Bob

[jsalley]

The tach takes its signal from the alternator stator. Have you noticed any problems with the charging system?

John

[tahomathundr]

John, I haven't noticed any problems but I am going to the boat today and will check it out. Thanks for the info. Bob

[Siamese]

I had the same problem with the tach on my boat, hull #82. The problem was intermittent. It took my dealer a looooooong time to fix it under warranty. They finally replaced the tach and the problem has never returned.

[JohnY]

Has anyone had a problem with the Tach reading 700-1000RPM too high. I fired up the engine last weekend and the tach read 1450 RPM at idle and went off the scale at cruising speed. The engine was not matching the rev's of the tach, thank goodness! I own C309 #20 "Big Luv" here in Seattle and this is the first time the tach has acted up. Any Ideas? Bob

I have a tachometer issue that may or may not be related. In the last month or so my tach will read over 500 rpm even when the motor is not running. Other than simply being a bad tach, I have no idea what might be causing the problem.

[tahomathundr]

John, My Tach also does not go to zero with the engine off. I checked the connections at the alternator and they are OK. Also it is charging normally so the only thing I can assume is that the Tach is bad. Mine will read about 700-1000 RPM high when running. I haven't had a response from Catalina as to the cost of a new one yet. It doesn't appear that they use the Yanmar tach as shown in my manual. Bob, C309 #20

[jsalley]

My tach doesn't zero when off either, and never has, but I'm not sure this is an indication of a problem. It works fine with the engine running (have checked it with a laser tach). Might be a quirk in the guage electronics.

[JohnY]

My tach doesn't zero when off either, and never has, but I'm not sure this is an indication of a problem. It works fine with the engine running (have checked it with a laser tach). Might be a quirk in the guage electronics.

I'm not too worried about it either as like you, things seem to read normally while running. If I'm in no particular hurry I try to run at about 2800rpm. I do 3000rpm if I am in a hurry. 3400rpm seems to be WOT. I've done a lot of reading and talking to marine engine people and our small diesel engines run best and last longest when run hard. They gum up and start giving us problems when we baby them. Warm ups should be short and we should try to get up to operating speed as quickly as possible.