Optional Engine Brake
ENGINE EXHAUST
1.6 ENGINE BRAKE
Engine braking is controlled by a pneumatically-operated exhaust brake in the center exhaust housing in conjunction with constant throttle valves on the cylinder heads. The exhaust
back-pressure is used by the exhaust brake to increase braking performance. The constant throttle valves use the air that escapes through them on the compression stroke to provide braking force.
The constant throttles are hydraulically-operated single piston valves which are built into the cylinder heads and positioned opposite the exhaust valves. When open, a link is created between the combustion chamber and the exhaust port. When the engine brake is switched on, the constant throttle valves are opened by hydraulic pressure.
NOTE:
When in emergency running mode (constant rpm), the engine brake can be activated only when the engine is in overrun. When constant rpm has been attained, the engine brake is automatically turned off.
1.6.1 Removal of Constant Throttle Valve
Removal steps are as follows:1. Remove the cylinder head. Refer to section 1.3.1.
2. Remove the fuel injector nozzle. Refer to section 2.6.1.
3. From the top of the cylinder head, remove the end cover on the constant-throttle valve.
See Figure 1-39.
1. End Cover 7. Spring
2. O-ring 8. Spring Guide
3. Piston Seal 9. Valve Stem Seal
4. Piston 10. Valve
5. Valve Keepers 11. Cylinder Head
6. Spring Retainer
Figure 1-39 Constant-Throttle Valve NOTE:
Insert a spacer beneath the valve head to prevent the valve from opening while doing the rest of the removal procedures. See Figure 1-40.
4. From the bottom of the cylinder head, insert a suitable spacer about 6.0 mm (1/4 in.) in height. See Figure 1-40.
1. End Cover 7. Spring
2. O-ring 8. Spring Guide
3. Piston 9. Valve Stem Seal
4. Piston Seal 10. Valve
5. Valve Keepers 11. Spacer
6. Spring Retainer
Figure 1-40 Cutaway View of Constant Throttle Valve
5. Using needle-nose pliers, remove the piston. Pull the piston and piston seal out of the valve bore. See Figure 1-41.
6. Inspect the piston for damage and signs of wear. Remove the seal ring from the piston and discard. If necessary, replace the piston.
7. Insert the constant throttle valve (CTV) spring remover (J–46401) down onto the spring retainer. Remove the valve keepers with a magnet. See Figure 1-42.
1. Valve Keepers 3. Spring
2. Spring Retainer
Figure 1-42 Compressing the Spring
8. Relieve the pressure on the spring. Remove the spring retainer, spring and spring guide.
For ease of installation, mark the spring retainer and spring guide with a paint pen.
9. Turn over the cylinder head. From the bottom of the cylinder head, draw out the valve and spacer. For ease of installation, mark the valve with a paint pen.
10. Using a small hook, remove and discard the valve stem seal.
NOTE:
Always replace the valve stem seal whenever the constant-throttle valve is removed.
11. Repeat this procedure for each constant-throttle valve.
1.6.2 Installation of Constant Throttle Valve
Installation steps are as follows:1. Lubricate the valve stem with a light coating of clean engine oil. From the bottom of the cylinder head, push the valve, as marked on removal, into the valve bore.
NOTE:
Insert a spacer beneath the valve head to prevent the valve from opening while installing the valve spring and piston.
2. Insert a suitable spacer about 6.0 mm (1/4 in.) in height. See Figure 1-40.
3. Install a new seal on the valve stem.
[a] With the fingers, press the seal onto the valve stem past the indentation that houses the valve keepers when the valve is installed.
[b] Insert the spring guide over the end of the valve stem and push down until the spring guide bottoms out.
4. From the top of the cylinder head, fit the spring and spring retainer, as marked on removal, onto the valve stem.
5. Push the spring down with the CTV spring remover and insert the valve keepers into the spring retainer. Push until they lock into place.
6. Install the piston and new seal, as removed. Be careful not to damage the seal on installation. See Figure 1-41.
7. From the bottom of the cylinder head, remove the spacer.
8. From the top of the cylinder head, install a new O-ring on the end cover.
9. Install the end cover.
10. Install the fuel injector nozzle. Refer to section 2.6.2.
11. Install the cylinder head. Refer to section 1.3.1.
12. Repeat this procedure for each constant-throttle valve.
1.6.3 Removal of Constant Throttle Valve Solenoid
Removal steps are as follows:
NOTE:
A Kent-Moore tool, CTV solenoid socket (J–47398) is required for this procedure.
1. Remove the lower exhaust manifold heat shield.
2. Disconnect the harness connector at the CTV solenoid.
1. EPV Harness Connector 2. Wiring Harness Bracket
Figure 1-43 Harness Bracket
3. Remove the bolt securing the wiring harness bracket and remove the bracket.See Figure 1-43.
4. Disconnect the harness connector from the EPV solenoid. See Figure 1-43.
5. Disconnect the harness connector from the and Oil Pressure/Temperature sensor oil filter.
6. Remove the plastic ties securing the harness to the brackets.
7. Pull the harness to the front of the engine through the opening between the oil filter housing and engine.
Figure 1-44 CTV Solenoid
8. Position CTV solenoid socket (J–47398) under the exhaust manifold and between the engine and oil cooler.
9. Slide the socket from rear to front until it is positioned over the solenoid.
NOTICE:
Ensure that the CTV solenoid harness does not get pinched . Damage to the harness could cause engine braking problems.
10. Using a 3/8 in. drive extension and a universal swivel remove the CTV solenoid.
11. Remove the O-ring from the solenoid and discard.
1.6.4 Installation of Constant Throttle Valve Solenoid
Installation steps are as follows:1. Install a new O-ring on the CTV solenoid and lubricate with clean engine oil.
2. Position the CTV solenoid into the oil cooler housing and start threads by hand.
NOTICE:
Ensure that the CTV solenoid harness does not get pinched . Damage to the harness could cause engine braking problems.
3. Using a 3/8 in. drive extension and a universal swivel torque, the CTV solenoid to 35 N·m (26 lb·ft).
4. Connect the harness connectors to the CTV solenoid, Oil Pressure/Temperature Sensor, and EPV solenoid. Secure harness with nylon tie straps.
5. Installed the removed lower exhaust manifold heat shield. Torque the bolts to 25 N·m (18 lb·ft).