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1977 Crusader 454CID 350HP

P

pkrawetzky

New member
Engines rebuilt in 2004.

After a 3 1/2 hour trip from Mystic to Newport, 1 hour trip to Block Island, and 1 hour to Misquamicut beach for fishing, my starboard engine alarm started buzzing about 20 seconds after starting the engine to move to a different fishing spot for the 5th time.

All gauges read normal (oil pressure about 40, temp about 170 and 14 volts). These were the exact readings (or pretty close) to what I saw on the longer legs of the trip so I know the gauges were working. I checked the engine and found nothing out of the ordinary including hand touching the manifolds (just as hot as the port), risers and elbows. They all compared to the port engine. I know this is not the best possible way to check but it seemed logical.

Having found nothing and seeing the gauges were working, I proceeded back to the dock running at 3300rpm for 45 minutes. All worked well on the way back but the engine buzzer still sounded.

When I got back to the dock I turned off the DC power and disconnected the batteries for an hour on advice from a mechanic. Reconnected the batteries and turn the DC switches back on. Started the engine and the buzzer stayed on. I found the wiring diagram in my Crusader owners manual and it appears this alarm is hooked to the temp, oil pressure and trans temp sensors. I touched the tranny fluid and it was cool.

Since the manual doesn't come with troubleshooting, I'm not sure what sensor to test or how to test them. As long as my gauges are working, how can I override the engine alarm? I know that is not the best solution but I am always constantly checking my gauges.

I am looking for advice and not "you shouldn't have moved that boat with the engine alarm buzzer sounding". Even the manual states to check gauages and it's ok to operate if everything is working.

Thanks in advance for any advice.
 
Try disconnecting the wire(s) from the various sensors one at a time until the alarm/buzzer stops. A ground from any of these will cause the buzzer to sound.
 
As you have discovered, the warning horn circuit has three switches in parallel. Any of them closing enables current to flow thru the horn (from the key switch) which activates it. Disconnecting the switches provides one approach for troubleshooting. If it turns out the switches are fine, then the 'warning horn wire' has a short to ground somewhere between the engine and the horn.
 
Follow suggestion above. You should have an oil pressure switch as well as an oil pressure sender. The sender is for the gauge, and the switch is for the alarm you usually hear when cranking the engine until oil pressure builds up. This switch is normally closed (contacts) until pressure builds up and opens the contacts thus shutting off the alarm. I suspect the switch is shorted (or wiring) or just not responding to oil pressure. The sender will be a large canister and the switch is much smaller, probably beside the sender.
 
Oil pressure switch/sender. Mine last about 8 years before they (all) eventually do this. When you get a new one, you can go to the automotive store, but make sure you get a 7psi, not the 20 psi version.
 
Nice chart! Thanks. The oil pressure switch was going to be my first stop in troubleshooting. Crusader had a great owners manual back in the days (I have the original) with a nice wiring diagram but no troubleshooting hints when it comes to the alarm.
 
here's a few of the basics for the warning horn circuit:

Horn supplied current from ignition switch in the RUN. Current flows thru horn (horn/buzzer sounds) when any of the switches (oil pressure, engine overheat, trans overtemp) close (switch turns ON). Only oil pressure switch is closed during startup (it opens once oil pump pressurizes galley it is threaded into). So the 'buzz' when the key is first turned on gives you an indication of that switch's state. if you have the key on (engine off) and disconnect the oil pressure switch and the buzz continues, there is a short to ground in the wire from the horn to the switches. The two overheat switches can't be tested without removing them.

that enough to get you probing in the right spots?
 
Re: 1977 Crusader 454CID 350HP - Low Oil Alarms Sensor - Resolved

Resolved!

Disconnected the wire on the low oil pressure sensor, turned the key on and no alarm. Reconnected the wire, started the engine and the alarm continued to sound. Replaced the sensor with Crusdaer 97767 sensor. Started the engine, pre-start alarm sounded and stopped when engine started.

Thanks to everyone who provided great information! It was a success...
 
I have just purchased a 1977 Uniflite with a 350 Crusader Big Block 454 HP twin engines. It does not have a service manual and I y could use the manual. Do you have it downloaded? Alternatively, is there anyway I could pay to purchase a copy? Thanks, Mermaids Drink Free
 
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