Attention: TDR Forum Junkies 
Warning Alarms are a fact of life in the Commercial fishing business to monitor fishold temperatures, water in the bilge and holds and of course your engines and gensets.
I watch my gauges religiously but consider a real commercial engine alarm a necessity. DC should have put a system in our expensive rigs but the beancounters in Deutchland probably vetoed the idea. I used one of the commercial alarms from Cole Hersee Co in MA but a guy could put one together from any good 12V buzzer or backup alarm. It's a simple installation. You add a coolant overtemp sensor to one of the many locations on the top of the engine on the starboard side and I used the oil input from the top of the Cummins oil filter. I used a "T" there because my ByPass filter inlet shares the same location. If you want to make your own, you need to observe a few rules. The oil and coolant sensors serve as the electrical gound, so no teflon or thread sealants are used. No current flows to the buzzer unless the oil pressure is too low or the coolant temp is too high. The Cole Hersee oil switch is set to 3-7 psi. The Coolant overtemp switch is set for marine engines at about 200 degrees, too low for truck use so I had to buy a switch for a higher temp. I chose a sensor for 240 degrees. I used an overtemp switch designed for an electric radiator fan for one of the Dodge engines. You need to use a unit with internal contacts that close with overtemp. You don't want one of the units with a variable resistor setup for an electrical temp gauge. These units must be on-off designs only. I added a bright red light that goes on with the buzzer but Cole Hersee now sells a combo light-buzzer unit that looks sweet. Cole#4112-RCBP. I pulled the power off an ignition switched-on fuse in the fuse panel. The buzzer is mounted under the dash left of the clutch to an existing stud which by the way is metric. So I drilled no holes. Some of the coolant sensors have long stems which may cause interference problems so choose one with a stubby stem if need be. I Added foil around the sensors to shield them from the exhaust manifold heat. The good news about this installation is that every time you turn on the ignition you're doing a system test, at least for oil pressure. The bad news is that the buzzer is loud enough to wake the dead! My wife has been giving me the evil eye lately and my daughter usually shrieks "Dad,what is THAT?" So I plan to add an interrupter switch between the 12V and the buzzer. It will probably be a spring loaded affair like an refrigerator door switch rather than an on-off toggle which could be accidentally left in the "OFF" postition which of course defeats the purpose of the alarm. With the current setup you can't listen to the radio either, but that's no issue for me since the only thing on the radio is Rap & hiphop anyway. West Marine is a huge supplier of boat gear and the Cole Hersee stuff is on pg 289 of the current catalog for under $35 depending on what you want. The higher temp coolant sensor will set you back $10 to $20 at NAPA.
By the way, my mama raised me up nervous and I even grounded the coolant switch and hit it with a propane torch to be sure the sensor worked. I hope most TDR people are more sane.
West Marine
Cole Hersee
I watch my gauges religiously but consider a real commercial engine alarm a necessity. DC should have put a system in our expensive rigs but the beancounters in Deutchland probably vetoed the idea. I used one of the commercial alarms from Cole Hersee Co in MA but a guy could put one together from any good 12V buzzer or backup alarm. It's a simple installation. You add a coolant overtemp sensor to one of the many locations on the top of the engine on the starboard side and I used the oil input from the top of the Cummins oil filter. I used a "T" there because my ByPass filter inlet shares the same location. If you want to make your own, you need to observe a few rules. The oil and coolant sensors serve as the electrical gound, so no teflon or thread sealants are used. No current flows to the buzzer unless the oil pressure is too low or the coolant temp is too high. The Cole Hersee oil switch is set to 3-7 psi. The Coolant overtemp switch is set for marine engines at about 200 degrees, too low for truck use so I had to buy a switch for a higher temp. I chose a sensor for 240 degrees. I used an overtemp switch designed for an electric radiator fan for one of the Dodge engines. You need to use a unit with internal contacts that close with overtemp. You don't want one of the units with a variable resistor setup for an electrical temp gauge. These units must be on-off designs only. I added a bright red light that goes on with the buzzer but Cole Hersee now sells a combo light-buzzer unit that looks sweet. Cole#4112-RCBP. I pulled the power off an ignition switched-on fuse in the fuse panel. The buzzer is mounted under the dash left of the clutch to an existing stud which by the way is metric. So I drilled no holes. Some of the coolant sensors have long stems which may cause interference problems so choose one with a stubby stem if need be. I Added foil around the sensors to shield them from the exhaust manifold heat. The good news about this installation is that every time you turn on the ignition you're doing a system test, at least for oil pressure. The bad news is that the buzzer is loud enough to wake the dead! My wife has been giving me the evil eye lately and my daughter usually shrieks "Dad,what is THAT?" So I plan to add an interrupter switch between the 12V and the buzzer. It will probably be a spring loaded affair like an refrigerator door switch rather than an on-off toggle which could be accidentally left in the "OFF" postition which of course defeats the purpose of the alarm. With the current setup you can't listen to the radio either, but that's no issue for me since the only thing on the radio is Rap & hiphop anyway. West Marine is a huge supplier of boat gear and the Cole Hersee stuff is on pg 289 of the current catalog for under $35 depending on what you want. The higher temp coolant sensor will set you back $10 to $20 at NAPA.
By the way, my mama raised me up nervous and I even grounded the coolant switch and hit it with a propane torch to be sure the sensor worked. I hope most TDR people are more sane.
West Marine
Cole Hersee
