Usage:
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NEVER REMOVE ANY ENGINE BRAKE COMPONENT WITH ENGINE RUNNING. PERSONAL INJURY MAY RESULT. |
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The Jacobs Engine Brake is a relatively trouble-free and maintenance-free device. However, periodic inspections and part replacement will need to be made from time-to-time. Use the following procedures to keep the engine brake in top condition.
This section will cover how to properly remove, clean and reinstall engine brake components. Use an OSHA-approved cleaning solvent when washing parts. Be sure to coat parts with clean engine oil when reinstalling them.
Control Valve
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REMOVE CONTROL VALVE COVERS CAREFULLY. CONTROL VALVE COVERS ARE UNDER LOAD FROM THE CONTROL VALVE SPRINGS. REMOVE WITH CARE TO AVOID PERSONAL INJURY. |
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1. Remove capscrews and covers from top of brake housing.
2. Carefully remove the control valve springs.
NOTE: Only one spring is used in the Model C-346 housing. Models C-346A and C-346B use two springs.
3. Using needle-nose pliers, reach into the bore and grasp the stem of the control valve. Pull valve straight up and out of its bore.
NOTE: The C-346 housing has a long-stemmed control valve. C-346A and C-346B housings use short-stemmed control valves.
4. Wash the control valves with approved cleaning solvent. Push a wire through the hole in the base of the valve to the distance required to ensure that the ball check is free. The ball should lift with light pressure on the wire. If the ball is stuck, replace the control valve. Dry the valve with compressed air and wipe clean with a paper towel.
Thoroughly clean the control valve bore in the housing, using clean paper towels.
Dip the control valve in clean lube oil. Holding the valve by the stem, let the valve drop into its bore. If binding occurs, the control valve should be replaced.
Solenoid Valve
1. Disconnect the solenoid harness.
2. For earlier style solenoid valves, unscrew with a Jacobs solenoid socket. Use a 12 pt. socket wrench to remove the current solenoid valves.
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DO NOT READJUST OR TAMPER WITH THE SOLENOID VALVE. ENGINE DAMAGE COULD RESULT. |
3. Remove and discard the three rubber seal rings. If the lower ring stays in the bottom of the housing solenoid bore, remove with a seal pick.
4. Wash out the solenoid valve with approved cleaning solvent. Use a brush to clean the oil screen. When clean, dry the valve with compressed air.
Clean out the solenoid valve bore in the housing. Use clean paper towels. Never use rags, as they may leave lint and residue which can plug the oil passageways.
5. Reinstall solenoid using new seal rings. Seat lower seal ring in the base of the solenoid valve bore. Wipe clean lube oil into and around the bore. Place upper and center seal rings on the solenoid valve body. See Figure 5-6 for seal locations.
Be sure the seals are seated properly and carefully screw the solenoid into housing without unseating the seals. Torque the valve to 5 lbft (7 N·m). Be careful not to twist the seals while installing.
Slave Piston
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WEAR SAFETY GLASSES. REMOVE SLAVE PISTON CAREFULLY. THE SLAVE PISTON IS RETAINED BY SPRINGS THAT ARE UNDER HEAVY COMPRESSION. IF THE FOLLOWING INSTRUCTIONS ARE NOT FOLLOWED AND PROPER TOOLS NOT USED, THE SPRING COULD BE DISCHARGED WITH ENOUGH FORCE TO CAUSE PERSONAL INJURY. |
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1. Remove the locknut on the slave piston adjusting screw. Back out the adjusting screw until the slave piston is fully retracted (screw is loose).
2. Using an arbor press, or a suitable clamp, slowly apply pressure to the retainer and remove the snap ring. Relieve the clamping pressure gradually until the springs are free.
3. Remove the retainer, springs and slave piston. Check for nicks or burrs that could cause binding. Clean piston in an approved cleaning solvent. Run a small wire through any bleed holes. Replace the piston if the ground surface on the outside diameter is questionable. Reassemble all parts, reversing the removal procedure.
NOTE: The correct slave piston must always be used with a specific Model housing. Check the Parts Manual.
NOTE: Model C-346B Engine Brakes have two styles of slave pistons and adjusting screws. Engine Brakes with serial number B360079 and higher have one hole in the slave piston and a slot across the plunger in the safety valve adjusting screw as shown.
Model C-346B Engine Brakes with serial number prior to B360079 have two holes in the slave piston and no slot in the plunger.
Master Piston
1. Remove button head screw, washer and master piston spring from brake housing.
NOTE: The master piston spring used on C-346B housings is shorter than the spring used on C-346 and C-346A housings. The shorter springs may be used as a replacement part on Models C-346 and C-346A.
2. Remove master piston from its bore. Needle nose pliers are usually needed to initially pull the piston up. If binding occurs, check for burrs or contaminates in lube oil. Clean in an approved solvent. Inspect the hard surface. Pitted, chipped, cracked or galled pistons should be replaced.
3. Reassemble in reverse order. When tightening the buttonhead screw, make certain the two spring tabs do not interfere with the sides of the master piston center raised portion.
NOTE: The tabs should be equally spaced from the raised piston area.
Reinstallation Of Housing Assembly
1. Install a new oil supply seal ring.
2. Always readjust slave piston lash. Use the procedure shown in Section 3, Page 14.
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SLAVE PISTON ADJUSTMENT MUST BE MADE WITH THE ENGINE STOPPED AND COLD. THE EXHAUST VALVES ON THE CYLINDER TO BE ADJUSTED MUST BE IN THE CLOSED POSITION. |