Starboard tach reading higher then port

[Boston-boater]

I have a 2000 310DA with twin 5.7 v-drives 375 hours on both. Recently my starboard tach is reading 800-1000 revs higher then port at all RPM speeds. I believe the reading is false because the synch gauge shows them synched, the boat tracks true with the rudders amidships and the port and starboard do not sound different. All other gauges on port and starboard read the same. Any thoughts as to cause and how to fix? Thanks.

 

[M99]

Sounds like the Tach gauge has failed. They are adjustable, but not 800 rpm off.

 

[Boston-boater]

Sounds like the Tach gauge has failed. They are adjustable, but not 800 rpm off.

Do you know if they are replaceable? And how to access them

 

[Northshore60]

On the back of the tach, there is a adjustment for 4,6 and 8 cylinder engines. Rotate this back and forth a couple times to the other settings and return to the 8 cylinder settings. This should fix it. Worked for me twice in the last 5 years.

 

[Boston-boater]

On the back of the tach, there is a adjustment for 4,6 and 8 cylinder engines. Rotate this back and forth a couple times to the other settings and return to the 8 cylinder settings. This should fix it. Worked for me twice in the last 5 years.

Great, I'll give it a try. How do I access the back of the gauge?

 

[Northshore60]

Mine has small balck Phillips screws around the fake wood dash. This holds the gauges in place from the back.

 

[Boston-boater]

Mine has small balck Phillips screws around the fake wood dash. This holds the gauges in place from the back.

Thanks, I'll give it a try

 

[AJSB]

On the back of the tach, there is a adjustment for 4,6 and 8 cylinder engines. Rotate this back and forth a couple times to the other settings and return to the 8 cylinder settings. This should fix it. Worked for me twice in the last 5 years.

Ive had similar problems with my tach and want to try this too. Might be a dumb question but is this fix performed with the engines running; power to gauges but engine off; or just at rest with no power to gauges?

 

[Northshore60]

At rest with no power on.

 

[Saverio]

I tried it over weekend and it worked!!!!!!!!
both tach are reading together so happy to see

 

[Saverio]

thanks

I actually changed my mind i want toast and jelly now