Re: [C320-list] tach showing strange values

[LambersvanDorp via C320-list]

What helped when our tach was showing strange values, was the following: at the back of there is a screwdriver- calibration knob. This knob appeared to make a bad contact. So mark its position, then use a screwdriver to turn it a couple times left and right and set it back to its original position. The contact is cleaned this way and in our case all worked fine again!

Rob van Dorp
BONVIEVENT
The Netherlands
(Sent from my iPhone)

> Op 13 okt 2025 om 22:32 heeft c320-lis...@lists.catalina320.com het volgende geschreven:
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> Today's Topics:
>
> 1. Re: V-berth dome light (Jarrett Henderson)
> 2. Re: V-berth dome light (Bill Allen)
> 3. Re: Engine pod questions (--Bill)
> 4. Re: Engine pod questions (SARA SCHROEDER)
> 5. Re: Engine pod questions (SARA SCHROEDER)
> 6. Re: Engine pod questions (surprise thompson87.com)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 13 Oct 2025 08:13:26 -0500
> From: Jarrett Henderson <jarretth...@icloud.com>
> To: C320...@catalina320.com
> Cc: "thompson87.com surprise" <surp...@thompson87.com>, C320 List
> <C320...@catalina320.com>
> Subject: Re: [C320-list] V-berth dome light
> Message-ID: <094E84DF-F3FB-4E7A...@icloud.com>
> Content-Type: text/plain; charset=utf-8
>
> I purchased some direct replacements that are LED and can be red or white from defender marine.
>
>
> Sent from my iPhone
>
>> On Oct 12, 2025, at 8:28?PM, surprise thompson87.com via C320-list <c320...@lists.catalina320.com> wrote:
>>
>> ?Does anyone know of a drop in replacement for the V-berth dome lights?
>>
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 13 Oct 2025 09:36:33 -0400
> From: Bill Allen <BA1...@comcast.net>
> To: C320...@catalina320.com
> Cc: Colleen Clay <collee...@gmail.com>, C320...@catalina320.com
> Subject: Re: [C320-list] V-berth dome light
> Message-ID: <CF8C8E99-CE5B-4F4A...@comcast.net>
> Content-Type: text/plain; charset=utf-8
>
> Yup! I got them. Work perfectly.
>
> Bill Allen
> Pegasus (1998 #536)
> Northport, MI
>
> Sent from my iPhone
>
>> On Oct 13, 2025, at 9:06?AM, Colleen Clay via C320-list <c320...@lists.catalina320.com> wrote:
>>
>> ?Catalina Direct has them in LED with switches.
>> Sent from my iPhone
>>
>>>> On Oct 12, 2025, at 18:29, surprise thompson87.com via C320-list <c320...@lists.catalina320.com> wrote:
>>>
>>> ?Does anyone know of a drop in replacement for the V-berth dome lights?
>>>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 13 Oct 2025 11:00:32 -0400
> From: --Bill <acke...@yahoo.com>
> To: C320...@catalina320.com
> Cc: KEN GEIGER <ken...@aol.com>, C320...@catalina320.com
> Subject: Re: [C320-list] Engine pod questions
> Message-ID: <62B09B1F-DFCD-4DE0...@yahoo.com>
> Content-Type: text/plain; charset=utf-8
>
> Here is a link to how a tach works on many small diesel engines https://answerpoint.blog/w-terminal-alternator-tachometer-wiring-guide
>
> I don?t have a Yanmar but i think it?s similar. I have a Beta 28 and had to replace my instrument. It had to be calibrated to the specific alternator pulley sizes in order to read correctly.
>
> ?Bill Ackerman
> #240 Tortuga 1995
>
>> On Oct 13, 2025, at 1:30?AM, KEN GEIGER via C320-list <c320...@lists.catalina320.com> wrote:
>>
>> ?We have the same or very similar symptoms on 765, 2000. Following with interest.
>> Ken GeigerNorthern Dream. #765
>>
>> Sent from AOL on Android
>>
>> On Sun, Oct 12, 2025 at 9:18 p.m., surprise thompson87.com via C320-list<c320...@lists.catalina320.com> wrote: My 1999 boat with Yanmar 3GM3F engine has developed an erratic tachometer. Does anyone have any advice about how to diagnose the problem?
>>
>> Perhaps relatedly, but perhaps not, I?ve noticed that when the engine is running the engine pod volt meter is pegging out way past the marked scale. It drops slightly when I turn on the blower but still reads way above the 14.3 volts I?m seeing on the batteries per my Victron battery monitor. Is it possible that the alternator is putting out a substantially higher voltage than the batteries are seeing?
>>
>> Scott Thompson
>> Surprise, #653
>>
>>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 13 Oct 2025 08:17:58 -0700 (PDT)
> From: SARA SCHROEDER <wanderin...@comcast.net>
> To: C320...@Catalina320.com, Jack Brennan via C320-list
> <c320...@lists.catalina320.com>
> Subject: Re: [C320-list] Engine pod questions
> Message-ID: <699340125.22678...@connect.xfinity.com>
> Content-Type: text/plain; charset=UTF-8
>
> I had the same problem with the tach bouncing all over the place and the culprit was a loose alternator belt. Once the belt was properly tighten up it stopped bouncing around.
>
> Sara
> Wandering Star
> Seattle
> #707/2000
>
>> On 10/12/2025 6:27 PM PDT Jack Brennan via C320-list <c320...@lists.catalina320.com> wrote:
>>
>>
>> At the rear of your engine is a sensor with two wires connected. These feed your tach. Pull the wires off one at a time and clean the connection. Make sure the connections are tight.
>>
>> If that doesn't make a difference, it's likely a ground connection in the instrument panel at your steering pedestal. Tighten all of the (usually) black wires and make sure the connections are clean.
>>
>> Lastly, the tach could be bad. I had to replace the one on my 1998. The sensors go bad only very occasionally.
>>
>> Jack Brennan
>> Sonas, 1998 Cataliina 320
>> Tierra Verde, Fl.
>>
>> ________________________________
>> From: C320-list <c320-lis...@lists.catalina320.com> on behalf of surprise thompson87.com via C320-list <c320...@lists.catalina320.com>
>> Sent: Sunday, October 12, 2025 9:16 PM
>> To: C320 List <C320...@Catalina320.com>
>> Cc: surprise thompson87.com <surp...@thompson87.com>
>> Subject: [C320-list] Engine pod questions
>>
>> My 1999 boat with Yanmar 3GM3F engine has developed an erratic tachometer. Does anyone have any advice about how to diagnose the problem?
>>
>> Perhaps relatedly, but perhaps not, I?ve noticed that when the engine is running the engine pod volt meter is pegging out way past the marked scale. It drops slightly when I turn on the blower but still reads way above the 14.3 volts I?m seeing on the batteries per my Victron battery monitor. Is it possible that the alternator is putting out a substantially higher voltage than the batteries are seeing?
>>
>> Scott Thompson
>> Surprise, #653
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 13 Oct 2025 08:17:58 -0700 (PDT)
> From: SARA SCHROEDER <wanderin...@comcast.net>
> To: C320...@Catalina320.com, Jack Brennan via C320-list
> <c320...@lists.catalina320.com>
> Subject: Re: [C320-list] Engine pod questions
> Message-ID: <699340125.22678...@connect.xfinity.com>
> Content-Type: text/plain; charset=UTF-8
>
> I had the same problem with the tach bouncing all over the place and the culprit was a loose alternator belt. Once the belt was properly tighten up it stopped bouncing around.
>
> Sara
> Wandering Star
> Seattle
> #707/2000
>
>> On 10/12/2025 6:27 PM PDT Jack Brennan via C320-list <c320...@lists.catalina320.com> wrote:
>>
>>
>> At the rear of your engine is a sensor with two wires connected. These feed your tach. Pull the wires off one at a time and clean the connection. Make sure the connections are tight.
>>
>> If that doesn't make a difference, it's likely a ground connection in the instrument panel at your steering pedestal. Tighten all of the (usually) black wires and make sure the connections are clean.
>>
>> Lastly, the tach could be bad. I had to replace the one on my 1998. The sensors go bad only very occasionally.
>>
>> Jack Brennan
>> Sonas, 1998 Cataliina 320
>> Tierra Verde, Fl.
>>
>> ________________________________
>> From: C320-list <c320-lis...@lists.catalina320.com> on behalf of surprise thompson87.com via C320-list <c320...@lists.catalina320.com>
>> Sent: Sunday, October 12, 2025 9:16 PM
>> To: C320 List <C320...@Catalina320.com>
>> Cc: surprise thompson87.com <surp...@thompson87.com>
>> Subject: [C320-list] Engine pod questions
>>
>> My 1999 boat with Yanmar 3GM3F engine has developed an erratic tachometer. Does anyone have any advice about how to diagnose the problem?
>>
>> Perhaps relatedly, but perhaps not, I?ve noticed that when the engine is running the engine pod volt meter is pegging out way past the marked scale. It drops slightly when I turn on the blower but still reads way above the 14.3 volts I?m seeing on the batteries per my Victron battery monitor. Is it possible that the alternator is putting out a substantially higher voltage than the batteries are seeing?
>>
>> Scott Thompson
>> Surprise, #653
>
>
> ------------------------------
>
> Message: 6
> Date: Mon, 13 Oct 2025 19:46:48 +0000
> From: surprise thompson87.com <surp...@thompson87.com>
> To: "C320...@Catalina320.com" <C320...@Catalina320.com>
> Subject: Re: [C320-list] Engine pod questions
> Message-ID:
> <DS0PR15MB60000EB945...@DS0PR15MB6000.namprd15.prod.outlook.com>
>
> Content-Type: text/plain; charset="utf-8"
>
> The Yanmar tachometer gets its reading from a magnetic flywheel sensor, not from the alternator, and so the link below does not apply.
>
> T. Scott Thompson
> Catalina 320 ?Surprise,? #653 (1999)
> surp...@thompson87.com
>
> -----Original Message-----
> From: C320-list <c320-lis...@lists.catalina320.com> On Behalf Of --Bill via C320-list
> Sent: Monday, October 13, 2025 11:01 AM
> To: C320...@catalina320.com
> Cc: --Bill <acke...@yahoo.com>; C320...@catalina320.com
> Subject: Re: [C320-list] Engine pod questions
>
> Here is a link to how a tach works on many small diesel engines https://answerpoint.blog/w-terminal-alternator-tachometer-wiring-guide
>
> I don?t have a Yanmar but i think it?s similar. I have a Beta 28 and had to replace my instrument. It had to be calibrated to the specific alternator pulley sizes in order to read correctly.
>
> ?Bill Ackerman
> #240 Tortuga 1995
>
>> On Oct 13, 2025, at 1:30?AM, KEN GEIGER via C320-list <c320...@lists.catalina320.com> wrote:
>>
>> ?We have the same or very similar symptoms on 765, 2000. Following with interest.
>> Ken GeigerNorthern Dream. #765
>>
>> Sent from AOL on Android
>>
>> On Sun, Oct 12, 2025 at 9:18 p.m., surprise thompson87.com via C320-list<c320...@lists.catalina320.com> wrote: My 1999 boat with Yanmar 3GM3F engine has developed an erratic tachometer. Does anyone have any advice about how to diagnose the problem?
>>
>> Perhaps relatedly, but perhaps not, I?ve noticed that when the engine is running the engine pod volt meter is pegging out way past the marked scale. It drops slightly when I turn on the blower but still reads way above the 14.3 volts I?m seeing on the batteries per my Victron battery monitor. Is it possible that the alternator is putting out a substantially higher voltage than the batteries are seeing?
>>
>> Scott Thompson
>> Surprise, #653
>>
>>
>
> End of C320-list Digest, Vol 4930, Issue 2
> ******************************************