Oil/temp warning

[KWKloeber]

thanks for your continuing interest Ken.
Oil switch is an open circuit with the engine off and closed circuit with the engine running.

My current project is the reconnect all of the leads from the engine to the harness that runs aft to the instrument panel.

@d

Did your mechanic do any troubleshooting (before or after replacing the switch and alarm)?

Your switch is operating correctly.  (The closed switch when you have oil pressure is supposed to power the fuel pump.)

With the key switch on, check the voltage at both switch terminals to ground.

Then we are going to take the switch out of the equation so we can test with the engine off (no oil pressure):

• Make up a short male-to-male jumper
  (or get a male-to-male adapter at the auto parts)

  
  
  

 
https://shop.advanceautoparts.com/p/dorman-disconnect-interior-adapter-assortment-85412/22141457-p

• Jumper together the two terminals.

  
  
  

• Tape it so it can't short out to the engine.
  
  

  
  
  

There should be TWO wires on one of the terminals, so check around to ensure there's nothing loose.  
Something appears to be abnormal on your harness because there **should** be a third wire (probably blue) running from the switch (your yellow terminal) to the alternator EXCITE terminal.

With the switch terminals jumpered and key on, listen for the fuel pump clicking.  
Does the alarm sound?  Faint or loud?


Report back!

The harness should have two wires on one terminal (red/white and ?blue?)

[dclintonbaker]

Progress report.
Yesterday I reconnected all of the wires of the harness.
The "tan" wire had become disconnected. I think that this one goes to the temperature switch. Difficult to spot that the two ends were not connected as it was at the back of the bundle.
The red wire with red stripe spade connector on the engine side had a poor crimp. The wire could be easily pulled out even with the heat shrink. I replaced both the male and the female sides.
Fired her up and the low oil pressure buzzer promptly stops!
But...none of the instruments working.
The black wire was not connected at the harness. Mechanic told me not needed. I connected it anyway. All the instruments now work with the exception of the fuel gauge.
I am currently trouble shooting the fuel gauge.
Again Ken, thanks for staying with me on this.
David.

[KWKloeber]

Edit - I've said it previously in this thread but will again. Tie down the wires so that harness movement doesn't get transmitted to the oil pressure switch terminals.  They fail too many times on the B engines. Wb doesn't put a spring-coil of wire on the sender wires to absorb vibration/movement. 
***

David where exactly where the two ends disconnected?  Were they quick-disconnect terminals?

Does she still have the black rectangular Westerbeke plugs on the harness near the back of the engine?

When did the fuel gauge stop working?

I would be rethining my choice of a mechanic if one claimed that I didn't need a harness ground wire connected!

[dclintonbaker]

Update. Everything now works as it should!

The original work was to replace the gearbox and engine mounts.
To do this the engine was disconnected and moved forward. When they reconnected it they replaced the connectors with heat shrink insulated spade connectors.

When I was having the issue with the alarm sounding continually I disconnected the harness and found that the red/white stripe wire (goes to the I terminal of the key switch) at the harness side was not crimped properly and slipped off the wire. I replaced both sides. The alarm now silenced when the engine started.

No instruments..connected the black wire of the harness and all the instruments worked with the exception of the fuel gauge.

I trouble shooted that and established that the plate of the transducer on the top of the tank was not earthed properly. I noticed a black wire (circled in the image) disappears through the floor of the lazarette in front of the tank and is routed though the locker under the bathroom sink and into the engine compartment..see the images. the mechanic claimed that this wire was never connected. I connected it to a good ground on the engine and the fuel gauge now works.

I confronted the mechanic with the poor crimp which was an awkward conversation. I am waiting to hear back with an apology.

Thanks for the tip about tethering the wiring to the oil pressure switch.

Thanks also the idea of changing mechanics.

[KWKloeber]

David
He probably didn't use (or have) the correct crimper frame for heat-shrink-insulated terminals.

Or lost his mind and didn't crimp before heat-shrinking?
Sometimes mechanics get ahead of themselves/distracted and the consequences multiply themselves exponentially.  Not an excuse, just reality.

I have stories!

Great that it all turned out for the better.