31640A 1 Mercruiser TRIM TAB ASSEMBLY

Introduction
This Special Instruction describes the retrofitting of jacket water heaters that utilize convection to circulate the jacket water to a jacket water heater that utilizes a pump in order to circulate the jacket water.Theory of Operation
Illustration 1 g01306992
Schematic of the coolant flowThe new jacket water heater is mounted to the rail on the left side of the engine. The new heater consists of a pump and a heater. The heater contains two heating elements and a thermostat.The heater is activated and deactivated by the generator set controller. When the generator set controller activates the contactor for the space heater, electrical power is supplied to the space heater (if equipped), to the pump, and to the thermostat.The pump continuously draws coolant from the rear of the engine block into the heater. The contacts of the thermostat will close when the temperature of the coolant is below the set point. The closed contacts of the thermostat complete an electrical circuit that supplies power to the coil of the contactor for the water heater. The contactor for the water heater supplies electrical power to the heating elements. The heating elements heat the coolant and the coolant is returned to the engine block by the pump.When the engine is running, the generator set controller deactivates the contactor for the space heater. This disables the pump, the thermostat, and the heating elements.Electrical RequirementsThe new jacket water heater receives electrical power from the generator's marshalling box.For the pump and the thermostat, the customer must provide a source of 220 VAC at 50 Hz or 240 VAC at 60 Hz. This electrical source must be protected by a 10 amp circuit breaker.For the jacket water heater, the customer must provide a source of 220 VAC at 50 Hz or 240 VAC at 60 Hz. This electrical source must be protected by two 25 amp circuit breakers.Parts Lists
Order the jacket water heater that is appropriate for the application. Refer to Table 1.
Table 1
Jacket Water Heater Groups    
50 Hz Generator Sets     60 Hz Generator Sets    
237-2236 Jacket Water Heater Gp     235-1224 Jacket Water Heater Gp    Order the additional parts that are appropriate for your engine. Refer to Table 2.
Table 2
Parts for Installation of Jacket Water Heaters on 3500 Generator Sets    
Part    Model of Generator Set and Quantity of Parts    
3508 Generator Sets with Low Voltage Output or with Medium Voltage Output (4160 VAC Maximum) 3508 Generator Sets with High Voltage Output (Above 4160 V)    3512 Generator Sets    3516 Generator Sets    
003-9163 Elbow     1     1     1        
006-5707 Pipe Elbow     1     1            
1L-4762 Pipe Elbow     1     1            
235-1225 Bracket     1     1     1     1    
235-1226 Hose As         1            
235-1227 Hose As         1         1    
235-1228 Hose As                 1    
235-1229 Hose As             1        
235-1230 Hose As     2         1        
237-0927 Bevel Washer     4     4     4     4    
239-1324 Contactor     1     1     1     1    
3H-9690 Elbow     1     1     2     2    
4B-9029 Pipe Nipple     1     1            
5P-1076 Hard Washer     10     10     8     8    
5P-3413 Pipe Sealant     1     1     1     1    
6V-8188 Nut     5     5     4     4    
7D-4092 Clip     2     2     1     2    
7X-0325 Bolt     4     4     4     4    
7X-0326 Bolt             1     1    
7X-0334 Bolt     1     1            
8S-5107 Spacer     2     2     1     1    
8T-4223 Hard Washer     1     1     1     1    Miscellaneous hardware is also required. Refer to Table 3.
Table 3
Miscellaneous Hardware    
Item    Purpose    
16 Gauge Wire     Connections between the marshalling box and the pump and the thermostat