The Water Temperature/Oil Pressure Alarm sounds continuously. The water temperature gauge and oil pressure gauge have normal readings. The engine has plenty of oil, the engine runs fine, there is ample water coming out of the exhaust and doesn’t overheat (tested 1 hour @ 2000 - 2500 rpm). When I stop the engine with the ignition switch in the ON position, the alarm continues until I pull the wire off of the Water Temperature - Alarm (with the wire to the Oil Pressure Alarm remaining connected). My guess is that I have a faulty Water Temperature - Alarm.
But before I replace the Water Temperature - Alarm, I’m wondering if the mechanics out there agree with my diagnosis. Also, (1) how can I test for low oil pressure without relying on the Oil Pressure gauge, and (2) how can I test for high water temperature without relying on the water temperature gauge?
I was told that the alarm will continue while the ignition is on because there is no oil pressure. So I treat the continuing alarm as a test of the low oil pressure alarm. This means that the alarm continues while I am preheating as well. A little annoying but I am told normal.
Disconnect both the oil and water temp alarm wires.
With the ignition switch to ON, shorting either one of these wires to ground should sound the alarm. Try both to test. If both sound the alarm the wiring is good.
Connecting the water temp wire to the water temp switch (if engine is not overheated) should not sound the alarm. If it does likely fault is a shorted water temp alarm.
Disconnect the water temp wire again.
Connect the oil pressure wire to the oil pressure alarm switch and the alarm should sound. Start the engine and the alarm should go quiet as soon as there is oil pressure. If there is no alarm then the oil pressure switch has stuck open and failed.
The alarm switches are very basic devices and should not fail but after 30 years who knows. Just before I bought my boat the oil pressure alarm switch failed by leaking all the oil into the bilge. The previous owner would have noticed but the alarm buzzer had failed and there was no alarm. I have never tested the water temp alarm but I guess you could by removing it and heating it with a lighter.
Thanks for your quick response. I’ll try the diagnostics that Tom suggested. Assuming that at least one alarm switch has surrendered after 34 years, I guess it might be a good idea to replace both.
The Westerbeke 13-21-27-33 Lube Oil Pump diagram on page 225 of Nonsuch Manual lists the Oil Pressure - Marine Alarm as Ref. #36-1: Switch, PN 30944 .
The Westerbeke 13-21-27-33 Cooling System diagram on page 235 of Nonsuch Manual lists the Water Temperature - Marine Alarm Switch as Ref. #34-1: Switch, PN 30125 (Water Temperature - Marine Alarm Switch) and Ref. #34-2: Bushing, PN 22131 (Reducer 1/4 NPT to 1/8 NPT-Marine).
Do you know if these are the correct parts needed to replace the Oil Pressure Alarm and the Water Temperature Alarm? Any idea where I can locate the parts?
My marina had the oil pressure switch in stock. They cross referenced this part #. It appears to be a very common item. All (internal combustion engine) cars seem to have the same part as well.
I did not ask about the water temp alarm switch but I guess same applies.
I don’t believe there is anything unique about a Westerbeke regarding oil press and temp.
Tom’s test sequence sounds like the logical checklist. On my Westerbeke 27 (same part number), I had the same problem. The alarm would start off gently and get progressively more annoying. When I disconnected the wire to it, the alarm stopped. The low oil pressure alarm was still functional and the coolant temperature was within limits. I purchased a new switch from my engine mechanic. Quite the case of sticker shock. After I installed it the nuisance alarm was no longer present.
Time now to move on to the other problems.
Happy sailing,
Peter Moodie
Nonsuch 30U Catalyst
Sidney, BC/Winnipeg, MB
I've ordered the water temperature switch from Westerbeke and expect it this week. I'm assuming the repair is to simply take the old one out and put the new one in. Is there anything more to it?