My tachometer started acting up.
At engine idle it would read zero revs and as you slowly open the throtlle the revs jump up to 3500 and then settles around 4000 with the engine probably at 2800 or so which is where we usually cruise.

I looked at the sender unit, pulled the wires off and noted significant corrosion. Cleaned terminal with fine emery paper and sprayed liberally with Corrosion Block. Restarted engine and to my relief the problem was fixed with tach behaving normally.

I am thinking of spending some time with the engine and doing that with all the electrical connections. Sooner or later they will all corrode.

BTW I replaced the oil pressure sensor (very surpising but it was only about $9.50) and the engine oil warning light and buzzer are working normally again.

Trevor Rabie

Dionysus C387 #8
Yanmar 3JH3E

I had the same experience and

The below advice, from Mack Boring, is for the Yanmar 3GM30F, but is essentially the same procedure for most engines:

“Coolant Change – Yanmar 3GM30FC (Japan, circa 1999)Coolant Change – Yanmar 3GM30FC (Japan, circa 1999)

Background:

Yanmar accepts the following antifreeze applications in their products, present and past models:

• Ethylene glycol-Changed annually regardless of hours of operation.
• Extended Life Antifreeze or Coolant (Meets or exceeds ASTM D3306 & D4985) Changed every two years or 250 hours whichever comes first.
• Yanmar Ultralife YG30
• Dex-Cool Long Lfe Coolant
• Havoline Extended Life Antifreeze

Benefits of extended life coolants:

• reduces hard scale build up
• better heat transfer
• no phosphate or silicate formation
• long term corrosion protection for aluminum, bronze and cast iron
• improved water pump life

Thomas J. Watts
Technical Support, Mack Boring & Parts Company
908-964-0700 ext. 286

tomw@mackboring.com

Equipment List:

• 0.5 gal Dexcool-type Extended Life Antifreeze (ex. Prestone 5yr/150000mi)
  Or 1

Galvanic corrosion (also called ‘ dissimilar metal corrosion’ or wrongly ‘electrolysis’) refers to corrosion damage induced when two dissimilar materials are coupled in a corrosive electrolyte.

When a galvanic couple forms, one of the metals in the couple becomes the anode and corrodes faster than it would all by itself, while the other becomes the cathode and corrodes slower than it would alone. For galvanic corrosion to occur, three conditions must be present:

1. Electrochemically dissimilar metals must be present
2. These metals must be in electrical contact, and
3. The metals must be exposed to an electrolyte

Hi all,

I would appreciate input on the underwater zincs used on my C380.  With the installed Yanmar, I’m aware that it lacks engine and heat exchanger zincs.

Since I’ve only needed to replace our zincs once, during her initial survey in 2007, I’ve forgotten many details.  Before rushing to judgment, about only replacing

It’s interesting that you have the Yanmar engine with C380 hull #184. I have C380 hull #185 and have a Westerbeke engine. I had thought that there were several Westerbekes after my hull #. Looks like I got one of the last Westerbekes or did the Previous Owner of your boat decide to wait for a Yanmar engine?

Paul McManus
Sea Sea Rider C380 #185
Port Orchard, WA

When we were looking to buy our C380, I called both Warren Pandy, and the Westerbeake representative that handled both warranty issues. I recall Warren explaining that there really wasn’t a specific hull number that could be sited as when the transition occurred. As I recall he mentioned that they tested the Yanmars on a boat or two prior to making the final decision to transition. He further indicated that even when the decision was final, the transition really didn’t occur