Carver Owners Forum

I have a 2002 Carver 356 aft cabin, with Crusader engines. Boat has a sync gauge which at a speed ex: 2500 rpm or any rpm on both tachometers the sync gauge indicates much more starboard … any thoughts

The sync gauge on my 3007 does the same thing. I use the tach's and the sound of the engines to know when they are in sync. I have only owned 3 twin engine boats and I have always coordinated the sound of the engines and the tachometers to gauge when they were in sync.

Check your connections/plugs at the tachs and synch gauges. If they use plugs, check the pins for corrosion. The synch gauge is likely getting signals off the back of the tachs. Could be a faulty gauge, or the culprit may in fact be one of the tachs not reading correctly and making you think it's the synch that's off instead. If your application uses analog signal gauges, look for a little cylinder selection rotary switch on the back of the tachs. Their contacts tend to corrode internally over time and give false readings. Take note of the position the switch is pointing to, then turn the switch back and forth several times. This sweeping helps clean the contacts internally. Don't force the switch to turn, if you feel some resistance, try depressing the switch a bit as that is required on some brands before you can turn them. Then return the switch to the position it was in when you started and test.

I have the same issue with my 2005. I installed a new module hoping that it would function properly. When installing, if I removed one of the wires of the old unit, I would lose the rudder indicator which is on the same instrument. So I left that wire from the old unit in place and added the new module . Low and behold, it is accurate up to about 1500rpm. Anything over that, it ain't worth nothin so I go ahead and use Admiral Grew's technique.

Interesting, master mechanic advised me a while ago to go by the sync and not the tach's?

The tachs will get you in the same range if they're working right but even when they are, unless they're a digital readout off an ECM an analog sweep utilizes an electric/mechanical mechanism that can be off by several rpm. The only way to tell for sure if they're right is to check rpm at the engine either through ignition, optical reading, or the ECM. A sync gauge while it may typically get it's signal piggybacked off the tachs, it's independent of the tach readings and what they're actually showing which is a good thing if the tach reading is slightly off due to internal or external influences. If your tachs are off, then it can be said that the sync is the gauge to go by but that's contingent on it working properly as well. With experience though, your ears can get you pretty close but it's nice to have a visual backup.

If all connection are good replace the little black box that is your sync module.

So, were do you get a replacement sync module?

Welcome to the forum......I see you have diesels.....different animal.

FWIW...engine loading, wind/waves/current will throw the sync off as well as the engine rpms rise and fall.