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Re: [SabreSailboat] Re: westerbeke alarm hijinx

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  • John Zeratsky
    Thanks John, very helpful!
    Message 1 of 7 , Sep 30, 2013
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      Thanks John, very helpful!


      On Mon, Sep 16, 2013 at 8:40 AM, sabre32sailor <sabre32sailor@...> wrote:
       

      Had some cycles on Saturday and went looking for the chirping beeper.
      I had been putting electrical tape on one half of it so it kept the noise manageable but still sang loud on low oil pressure.

      Anyways, I started by trying finesse the beeper out. You can grab from behind with set of vice grips and then turn the knurled knob on the front, or you can put your small screwdriver into 1 of the 4 slots on the front and then turn the knob. When you remove it, you will have 2 wires. One from the key, the other to the engine sensors. The wiring follows the main harness to the rear of the motor next to the solinoid. From there, it comes down the starboard side of the motor just below the injectors, pops up by the thermostat for the overheat sensor. It then goes back 10" and goes down to the oil pressure sensor that is just behind the mount for your throttle cable. I bring this up because the westerbeke exploded diagrams are not too clear where the sensors are.

      How it works is the beeper has power, but the ground goes down circuit. When the sensor goes off (low oil pressure or overheat condition), the sensor grounds to the engine block completing the circuit and the beeper goes off.

      So I disconnected the ground wire at the beeper and inserted my multimeter in series. When I energized the circuit, I got a strong beeping and 11.8 volts. when I kicked the motor over, instead of getting 0v, I got .4 Hummm, there is a partial short circuit here.
      I removed the clips to the 2 sensors which should have caused an open ground circuit, but continued to get .4v instead of 0.

      Shut the motor down and when looking. Main harness connector at rear of motor looked like new, as did the 2 spare wires (1 of which is the sensor wire). The wiring on the motor is put into those black plastic wiring tubes that are used on computers. The kind that are split down the length.
      http://www.homedepot.com/p/GE-6-ft-Cable-Neat-Organizing-Tubing-Black-43037/203716823#.UjckrMaTjRg

      I opened these up and found a lot of oil and solvent residing in there. On the last 2 feet, they use a simple plastic wire wrap. Both had melt marks and oil reside. I remove the looms and cleaned all the wires and tubing before reassembly. Attached the sensors and re-ran the tests. I was now down to .1v. I looked at the oil pressure sensor and saw it was coated with a find coat of rust including over the plastic insulator from the wire clip. Likely from overflow from the cooling system. Anyhow, I wire brushed it clean as Hansen has already closed for the weekend. When I fired the motor up, the buzzing was gone. Sweet silence!!!
      I was still getting a reading on a shut down motor, but it was down to .04v which may have been my cheap multimeter.

      Engine is quiet as can be. Removed tape from front of buzzer. Everything is reassembled. I will buy new wire loom tubing to clean everything up and likely will replace the oil pressure sensor this winter. My gut feeling is some oil on the outside of the wiring found a cut or melt area and partically shorted. I was not able to find any damage to the wiring, but there are some places you just cannot get to without disassembling half the motor.

      I highly suggest you check:
      -at rear of engine where main harness clips to engine harness.
      - the next 2 feet of wire as it snakes between many rough components.
      -Open the loom and inspect for oil, or water.
      - Make sure sensors are clean.

      All these fun and games cost me ~3 hours of my time.

      john



      --- In Sabresailboat@yahoogroups.com, "sabre32sailor" <sabre32sailor@...> wrote:
      >
      > Got a problem that has me scratching my noggin.
      > Deals with warning beeper on a Westerbeke.
      > As you know the gauges run on their own senders. Both oil pressure and water temps are spot on when running the motor.
      >
      > But the beeper has developed a weird chirping sound when the engine is running.
      > I know you are going to say it is one of the sensors for the beeper, but hold on...
      >
      > System logic:
      > The wiring for the beeper takes 12 volts from the key and goes to the beeper.
      > The beeper ground wire goes toward the motor to the top of both oil and water alarm sensors (separate from gauge sensors). Basicaly when you have low pressure or high water temps, the sensor grounds the wire to the block which completes the circuit and the BEEP BEEP BEEP starts. Either sensor grounding will engerize the circuit, as they are connected in parralell off the water temp plug. As long as the water is cool and oil pressure is up, the ground wire is open so the circuit does not energize. Ok, electric class is now over.
      >
      > I figured I was looking at a bad sensor that was partially grounding. So I disconnect the sensor wire at the water temp. The beeper was still chirping. So it was looking like the oil pressure sensor. So I unclip that sensor while leaving the water temp sencor off, but the buzzer was still chirping at me. What the????
      >
      > I am thinking there must be a high resistance short in the ground wire from the beeper. But now the weird part. When I shut down the motor by cutting off air with both sensors disconnected, instead of quiet or that chirping, I get the full BEEP BEEP BEEP.
      >
      > So, anyone run across this one?
      > Anyone remove the beeper? I would like to pull the beeper and wire brush the contacts to see if the short is at the beeper mount.
      >
      > Only good is a bit of electrical tape on the beeper quiets it enough to make it bearable while still alerting one to a true low pressure condition.
      >


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