Exhaust
Base engine	Speed	backpressure limit
All JU4		30
All JU6 except models below		30
UF34, UF54, UFAB76, UF84	2800	25
UF34, UF54, UF84	3000	25
UF30, UFG8,
UFABL8, UFM8, UF58,	1470	20
UF68, UFAAPG

 
 
148
Note: Intake Air Shutoff Valve - Engine may include an intake air shutoff valve as an optional feature that is activated by an overspeed event and provides a positive shutoff of combustion air to the engine. The optional air intake shutoff valve has not been evaluated by UL as part of a UL Listed fire pump driver.
 
 
147

Base engine	Speed	Air filter restriction
All JU4		10
All JU6 except models below		12
UF30, UFABL8, UFM8, UF58, UF68, UFAAPG	1470	10
UFD0, UFD2, UF30, UF32, UFABL0, UFABL2, UFM0, UFM2, UF50, UF52, UF60, UF62	2350	13
UFD2, UF32, UFABL2, UFM2, UF52, UF62	2600	13

 
 
159
 
3.5.5 Mechanical Engine Control and Alarm Board (MECAB) Speed Switch Troubleshooting
This engine may be equipped with a speed switch p/n C071571 capable of sensing engine sensor malfunctions and/or electrical over-current(s) on engine alarm circuits and alerting the user via flashing status lamps. This flashing status indication is done so with the red “OVERSPEED SHUTDOWN” lamp on the outside of the Clarke instrument panel (Figure #37A) and a red LED located on the middle of the speed switch inside of the Clarke instrument panel (Figure #37B). In addition to these flashing status lamps, a “Low Engine Coolant Temperature Alarm” is sent via engine / fire pump controller inter-connect circuit #312 as a means to alert the user outside of the engine room.
Note: When first applying battery power to the engine, or after activating the overspeed reset switch, the OVERSPEED SHUTDOWN lamp and red LED on the speed switch will flash several times. This is an “INITIALIZATION PATTERN” and is normal.
This will be referred to in the following troubleshooting section.
 
Figure #37A
List of Troubleshooting Malfunctions
Two (2) blinks – Electrical Current Exceeds 10 Amps on Alarm Circuits: Status lamps will flash two times continuously on the Clarke instrument panel and a “Low Engine Coolant Temperature” alarm will be sent to the fire pump controller via circuit #312.
Cause:
Electrical current exceeds 10 amps on one or more engine / fire pump controller inter-connect circuits
Engine run alarm (#2)
Engine overspeed alarm (#3)
Engine low oil pressure alarm (#4)
Engine high coolant temperature alarm (#5)
Engine low coolant temperature alarm (#312)
 
Corrective actions:
Check each of the above circuits to determine which contains the current overload.
Once circuit(s) overload are corrected: On the Clarke instrument panel, operate the “OVERSPEED RESET” switch for two (2) seconds and release (Figure #37C).
 
The “INITIALIZATION PATTERN will flash. This is normal. The continuous two (2) blink flash sequence should turn off at this point.
Three (3) blinks – Engine Coolant Temperature Sensor malfunction: Status lamps will flash three times continuously on the Clarke instrument panel and a “Low Engine Coolant Temperature” alarm will be sent to the fire pump controller via circuit #312.
 
Cause:
Engine coolant temperature sensor circuit is open or closed
Corrective Actions:
Verify wiring and connector plug at engine coolant temperature sensor are secure. Sensor is located behind engine thermostat housing
 
On the Clarke instrument panel, operate the “OVERSPEED RESET” switch for two (2) seconds and release. (Refer to Figure #37C).
The “INITIALIZATION PATTERN will flash. This is normal. The continuous three (3) blink flash sequence should turn off at this point.
 
If problem still exists, replace engine coolant temperature sensor, Clarke part number C071607
Five (5) blinks on instrument panel – Oil pressure switch or Engine speed sensor (magnetic pick-up) malfunction: Status lamps will flash five times continuously on the Clarke instrument panel and a “Low Engine Coolant Temperature” alarm will be sent to the fire pump controller via circuit #312.
Cause:
Oil pressure switch failure or magnetic pick-up failure.
 
Corrective Actions:
Oil Pressure switch check
Verify wiring and connector at engine oil pressure switch are secure. Pressure switch is located on left side of engine (JU models) and right side of engine (JW models)
With engine off, check continuity between the two terminals on the oil pressure switch. Note, do not disconnect wires when performing this task.
 
If circuit is open, replace oil pressure switch, Clarke part number C072011.
After new switch is replaced: On the Clarke instrument panel, operate the “OVERSPEED RESET” switch for two (2) seconds and release.
(Refer to Figure #37C)
The “INITIALIZATION PATTERN will flash. This is normal. The continuous five (5) blink flash sequence should turn off at this point.
 
If circuit is closed, the oil pressure switch is not damaged and is working normally as expected. Proceed to engine speed sensor check, below. Engine speed sensor (magnetic pick-up) check Verify wiring and connector at engine speed sensor are secure. Magnetic pick-up is located on top of the flywheel housing.
 
With engine running, verify that the tachometer is functioning normally.
Refer to section 3.5.4 of Engine Operator’s Manual to properly reposition the magnetic pick-up if tachometer is not functioning.
Once magnetic pick-up is repositioned: On the Clarke instrument panel, operate the “OVERSPEED RESET” switch for two (2) seconds and release.
(Refer to Figure #37C).
 
“OVERSPEED SHUTDOWN” lamp will flash a sequence of one (1) blink, then four (4) blinks. This is normal. The continuous five (5) blink flash sequence should turn off at this point. If problem still exists, replace engine speed sensor (magnetic pickup), Clarke part number C071883.
 
3.5.6 FIELD SIMULATION OF PUMP CONTROLLER ALARMS
Field simulation of (5) pump controller alarms
• Alarm 1: Over speed Shutdown: Follow over speed verification steps per section 3.5.3.
• Alarm 2: Low Oil Pressure: With the engine running, jumper across two outer terminals with wires attached to the engine mounted Low Oil Pressure switch.
Wait for 15 seconds and controller alarm will activate.
• Alarm 3: High Engine Coolant Temperature: With the engine running, set the High Engine Coolant Temperature DIP switch to “ON” (see Figure #37D). Use a fine pick or small screwdriver and slide the white slider to the left. Wait for 30 seconds and controller alarm will activate. Set white DIP switch slider to “OFF” (right) when simulation is complete.
 
Low Coolant Temperature Simulation switch
High Coolant Temperature Simulation switch
OFF
ON
Figure #37D
• Alarm 5: Overcrank: NEVER shut off the fuel supply to the engine to prevent it from starting. Shutting off the fuel supply will cause an air lock condition in the fuel system and possibly cause fuel system component damage.
ETR Governor Solenoid: Activate and hold the Overspeed Reset switch while performing the overcrank test. Switch must be held continuously each time the engine attempts a crank start. This will allow the engine to crank only but will prevent it from running.
ETS Governor Solenoid: Use manual stop override to prevent the engine from starting during the cycle-crank testing. Override must be held continuously each time the engine attempts a crank start. This will allow the engine to crank only but will prevent it from running.
 
154
3.4.7.1 Raw Water Supply
Most Clarke diesel engine fire pump drivers are heat exchanger cooled and some engines also have a charge air cooler (CAC) that uses raw water to cool the air before entering the intake manifold. If you have a radiator cooled Clarke engine, you can disregard this section. Heat exchanger cooled diesel engine drivers require a clean source of pressurized water from the discharge side of the fire pump in order to keep the engine from overheating by providing a specified minimum amount of raw water flow.
3.4.7.2 Cooling Loop
Note: Engine may include a cooling loop as an optional feature and has not been evaluated by UL as part of a UL Listed fire pump driver.
Figure #35D shows the standard NFPA 20 cooling loop piping arrangement. The cooling loop consists of an Automatic flow line with a 12V or 24V solenoid valve (HSC and ES pump applications only) that is energized to open anytime the engine is called upon to run from either the fire pump controller or from the engine instrument panel.
NOTE: VT type pumps applications do not require a solenoid valve in the Automatic flow line.
NOTE: With the Mechanical Engine and Alarm Control Board, See section 3.5.5, the solenoid valve will open 15 seconds after engine shutdown and will stay open for 60 seconds. This allows for raw water to flow through the heat exchanger and reduce the heat soak rise caused in the engine.
The second flow line is called the Manual by-pass line and it can be opened at any time if for any reason the engine shows signs of overheating. Each line has two (quarter turn) shutoff values installed and the normal position of the shutoff valve is to remain open in the Automatic flow line and remain closed in the Manual by-pass flow line.
NOTE: Opening up both lines to flow is never a problem should there be some concern of engine overheat, especially if there is an emergency situation. The Manual by-pass line can only be opened by an operator in the pump room.
The shutoff valves are all identified to show which are Normally Open (Automatic flow line) and which are Normally Closed (Manual by-pass flow line).
The shutoff valves are also used to isolate water pressure in the event of maintenance to pressure regulators, strainers and solenoid valve. Shutoff valves in the automatic flow line are provided with lockable handles for cooling loops that have been tested to FM requirements.
In each flow line there is also a pressure regulator. Each pressure regulator protects the downstream piping from over-pressurization which includes the tube side of the engine shell & tube heat exchanger (or CAC) and to control raw water flow rate. Typically the pressure regulators are set to limit downstream pressure to 60 psi (4 bar). There is a pressure gauge installed just upstream of the engine heat exchanger (or CAC) and downstream of the each pressure regulator. Under normal engine operating conditions with adequate cooling water flowing thru the heat exchanger (or CAC) this gauge should typically read below 20 psi (1.4 Bar).
Strainers are used to remove debris from the raw water supply. One strainer is in the Automatic flow line and the other is in the Manual by-pass flow line.
Note: See section 3.4.7.5 regarding strainer maintenance.

Standard Cooling Loop
Figure #35D
3.4.7.3 Setting Raw Water Flow Rate
The proper amount of raw water flow thru this line is of the utmost importance, and the pressure gauge value does little to indicate if there is sufficient flow. When the engine is exercised weekly, the amount of raw water flow exiting the piping to a floor drain should always be checked to verify it does not appear to have diminished.
During initial commissioning of the engine, it is important to correctly set the raw flow rate going thru the cooling loop. Each Clarke engine model has an Installation and Operation (I&O) Datasheet that provides basic operating conditions of the engine and most values are given based upon engine speed. You will find this datasheet in the Technical Catalog that is shipped with the engine for your specific Clarke model. This datasheet must be available during commissioning in order to set the proper minimum raw water flow. You will need to measure the raw water temperature and then find the value for recommended minimum raw water flow at your measured raw water temperature on the I&O Datasheet and then; with the fire pump flowing 150% of rated flow, and the Automatic flow line open; set minimum flow by using the adjusting screw at the top of the pressure regulator.
NOTE: To increase flow turn the adjusting screw clockwise and to reduce flow turn the adjusting screw counterclockwise.
You will need to capture the flow for a specific amount of time coming out of the heat exchanger and going to a floor drain in order to establish a reasonably accurate flow rate value. Using a container or bucket of known volume, record the time required to fill the container and compare to the gpm or L/min value provided on the I&O datasheet.
THIS IS CRITICAL FOR PROPER ENGINE COOLING AT MAXIMUM PUMP LOAD! After setting the pressure regulator in the Automatic flowline, open the Manual by-pass line valves, and then close the Automatic flowline valves and repeat the above process in order to set the flowrate going thru the pressure regulator in the Manual by-pass line. Once this is completed; close the Manual bypass valves and open the Automatic flowline valves to restore conditions back to normal.
3.4.7.4 Raw Water Outlet
NOTE: NFPA 20 does allow for the heat exchanger outlet flow to be returned to a suction reservoir. This makes it very difficult to measure the flowrate. When discharging to a suction reservoir, NFPA provides additional requirements:
1) A visual flow indicator and temperature indicator are installed in the discharge (waste outlet) piping.
2) When waste outlet piping is longer than 15ft (4.6m) and / or the outlet discharges are more
than 4ft (1.2M) higher than the heat exchanger, the pipe size increased by at least one size.
3) Verify that when the correct flow rate is achieved that the inlet pressure to the heat exchanger (or CAC) does not exceed 60psi (4bar)
If you have such an installation, it is recommended that you run the engine for a period of time at firepump 150% flow and confirm the visual flow indicator is showing water flow, the temperature rise is not excessive (usually no more than 40F (4.5C) over ambient raw water temperature) and the engine is showing no signs of overheating.
3.4.7.5 Raw Water Quality, Strainers and Deterioration of Heat Exchanger (or CAC)
Over time, as the heat exchanger (or CAC) begins to plug and foul, this pressure will rise and the flow will diminish which could mean that the heat exchanger (or CAC) may have to be replaced.
It can be not stressed enough how important it is to keep these strainers clean: Most engine failures occur due to plugged cooling loop strainers! If the raw water supply has debris in it (leaves, stones, etc) as the strainer accumulates more debris (that will not pass thru it), the flowrate will continue to diminish which will eventually starve the engine of adequate cooling water flow which will lead to engine overheat and catastrophic engine failure. When this occurs you have no fire protection! Clarke recommends that after the initial engine commissioning and also prior to each weekly exercise of the engine / fire pump set, both strainers be removed and cleaned and then re-installed before starting the engine.
3.4.7.6 Backflow Preventers
NFPA20 allows for the use of backflow preventers in the Automatic and Manual flow line of the cooling loop as required by local code. For specific application information contact factory.
3.4.7.7 Raw Water Outlet Temperature
Certain local codes may not allow you to discharge the waste water outlet from the engine heat exchanger either due to its temperature or it now being considered hazardous waste. It is
recommended you always check local codes regarding waste water discharge.
3.4.8 Flow Paths of Engine Cooling System
The engine coolant flows through the shell side of the heat exchanger (or radiator), engine coolant pump, oil cooler, engine block and cylinder head, jacket water heater, thermostat, expansion tank, and coolant recovery tank (if equipped).
On heat exchanger equipped engines raw cooling water flows through the tube side of the charge air cooler, if equipped, and the tube side of the heat exchanger.
Refer to Figures #35E for heat exchanger cooled engines and #35F for radiator cooled engines for cooling system flow path diagrams.
 
Figure 35F- radiator cooled engines
3.4.9 IMPORTANT SERVICE NOTICE
Any time an engine experiences a high coolant temperature alarm condition the primary cause of the overheat must be determined and the cause corrected to prevent a recurring overheat event.. Additionally, if an event of a restricted flow, collapsed hose, insufficient coolant level or failed pressure cap is experienced, further investigation of the cooling system is required.
 
1) The coolant shoud be drained (after deenergizing the coolant heater
2) Replace the engine thermostat(s)
3) Remove the engine water pump and inspect the impeller and seal for damage, replace as necessary. Reassemble and refill coolant according to the Installation and Operations Instruction Manual.
4) Run the engine to verify normal operating temperature.
3.4.9.1 Water Pump Cavitation
Cavitation is a condition that occurs when bubbles form in the coolant flow in the low pressure areas of the cooling system and implode as they pass to the higher pressure areas of the system. This can result in damage to cooling system components, particularly the water pump impeller and cylinder liners.
Cavitation in an engine can be caused by:
 Improper coolant
 Restricted coolant flow caused by collapsed hose or plugged system
 Coolant fill cap is loose or unable to retain the required pressure
 Insufficient fluid level
 Failure to de-aerate
 Overheat
151
3.4.1 Intended Engine Operating Temperature
The JU and JW engines are provided with either a heat exchanger or radiator to maintain the engine coolant temperature within recommended operating guidelines.
The JU4H, JU6H, and JW6H have an intended engine operating temperature of 160º F (71ºC) to 185º F (85º C). A high coolant temperature switch is provided to indicate a high coolant temperature alarm at 205º F (96º C) for heat exchanger cooled models and 215°F (102° C) for radiator cooled models.
 
2.6.4 Emergency Operation – ETR Engines Only
UL/FM Energized To Run (ETR) engines only In the event that the speed switch fails to energize the engine’s fuel injection pump solenoid, the engine instrument panel has been equipped with an Emergency Run Switch. This switch sends battery voltage directly to the fuel injection pump solenoid which allows for operation of the engine.
Additionally, the Emergency Run Switch will activate the engine raw water cooling loop solenoid if the engine is equipped with one.
If engine fails to run with standard starting procedures, follow these steps to start engine with Emergency Run Switch:
1. Open the door of the instrument panel
2. Locate the Emergency Run Switch, denoted by the yellow indication label
3. Remove the lock-out screw
4. Toggle switch to the ON position
a. Battery voltage will be sent to the fuel injection pump solenoid and the raw water cooling loop solenoid
5. To shut engine down ensure engine mode selector switch is set to Auto/Manual Stop, fire pump controller is keyed to OFF, and toggle the engine Emergency Run Switch to OFF position.
Note, activating the Emergency Run Switch will energize the fuel solenoid and the raw water cooling loop solenoid until the switch is returned to the OFF position. The switch should only be used as a manual, emergency means for operation of the engine in the event of speed switch failure. Replace speed switch immediately upon finding failure.
  
UL/FM Front Opening Instrument Panel
1 Emergency Operating Instructions
2 Automatic-Manual Mode Selector
3 Manual Crank Controls
4 Overspeed Reset
5 Manual Mode Warning Light
6 Overspeed Verification
7 Overspeed Indication Light
 
120
Turn off all cooling water lines.
109
Test for parallel and angular alignment with a straight edge and feeler gauge as shown in manufacturer’s instructions (at the end of this section). With coupling halves stationary, make trials at four places 90º apart. Perfect alignment occurs when a straight edge is level across the coupling halves and the same gauge just enters between the halves, both conditions at all points.
 
37
b) Air temperature

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