This custom made oil pressure sender may used in Yanmar Diesel engines aboard boats built by Catalina Yachts. The standard Yanmar engine uses a sender with non-standard threads and an impedance matched to European instruments. In order to use American instruments aboard your Catalina, you must replace the standard Yanmar sender with this custom sender.
These replacement oil pressure gauge senders are machined to fit Yanmar's threads and the impedance matches that of our #T2023 oil pressure gauge shown below.
1) Unless they are intimately familiar with Yanmar engines installed on Catalinas, it is highly unlikely anyone will be aware of this custom part. Speak to any normal Yanmar parts source either at a boat yard or any of Yanmar's many distributors across the country and it is likely you will receive incorrect information due to the specialized nature of this information.
2) This is a sender for a pressure gauge, not an oil pressure switch used for an alarm.
3) Some customers report that, when installed in a newer boat with a Yanmar engine, there appears to be something in the circuitry between the sender and the panel that interprets the variable resistance of the sender and creates an on-off signal for the warning buzzer. If your panel originally had a buzzer with no oil pressure gauge, simply hooking the same wire to a new gauge may not work. Some customers have solved this problem by running a separate wire directly from the sender to the instrument.
4) Regardless if you are installing an oil pressure sender or an oil pressure switch, never use any type of Teflon tape or pipe joint compound on the threads. The sender or switch are modulating the connection of the instrument to the ground by way of the engine block. If you insulate the threads, they can't make the connection to ground and the instrument will not function properly.
Owners reporting these details undoubtedly were not diesel mechanics and neither are we! You may want to check with your mechanic before starting this installation.