Here is the instruction show you guide on how to perform mechanical cylinder compression test for Detroit DDC-SVC-MAN GHG17 heavy duty engine.
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Note : This test should be performed only if directed here by a diagnostic procedure.
Perform the following steps for a mechanical compression test on a GHG17Heavy Duty DD Platform Engine:
Jake Brake /piston
Valve lash/valve train damage
Camshaft timing
Cylinder liner/ring damage
Fuel injector hold-downs
Blown cylinder head gasket
Cracked cylinder liner or cylinder head
Valve or seat damage
Note : First perform the Relative Cylinder Compression Test using DiagnosticLink.If results indicate a weak cylinder, perform this mechanical compression test.
1 The valve lash needs to be checked before the mechanical compression test is performed. Refer to section “Setting the Valve and Engine Brake Lash” and adjust as necessary, if no adjustment is needed continue to step 2.
2 Run the engine and bring the engine coolant temperature to normal operating range, 88 to 96°C (190 to 205°F).
3 Disconnect the batteries and plug the batteries into a battery charger. Refer to OEM procedures.
4 Remove rocker cover. Refer to section “Removal of the Rocker Cover” .
5 Remove the fuel injector harness.
6 Disconnect electrical contacts at the fuel injectors.
7 Disconnect the two wiring terminals going to the Jake Brake ® solenoids.
8 Disconnect the 14-pin fuel injector harness connector.
9 Remove the spring clip holding the fuel injector harness connectors to camshaft frame.
10 Remove the fuel injector wiring harness(es).
11 Remove the high pressure fuel line from all cylinders. Refer to section “Removal of the High Pressure Fuel Injector Lines – Two-Filter System” .
12 Remove all fuel injectors. Refer to section “Removal of the Fuel Injector – Two-Filter System” .
13 Remove excess fuel from cylinders using a vacuum pump.
14 Install the compression test adapter (J-47411) into the fuel injector bore in the cylinder head.
15 Install the fuel injector hold-down clamp and bolt. Torque the bolt to 20 N·m (14 lb·ft) + 90 degrees.
16 Install the fuel rail plug (J-48704 or W470589129100).
17 Install a hold-down bolt onto the Jake-Brake ® solenoid and snug the bolt.
18 Reconnect the batteries; keep the battery charger plugged into the batteries.
Note : Verify that the battery voltage does not go low enough to affect engine cranking speed. If the cranking speed is affected, then the results will be inaccurate. A battery charger will help to maintain an acceptable battery voltage.
19 Using DiagnosticLink start the Mechanical Compression Test routine, this will disable fuel from the Quantity Control Valve.
20 With the batteries fully charged, crank the engine over five compression strokes at 150 rpm or greater using the starter motor. Record the compression reading on the gauge.
21 At normal operating temperature, the compression reading should be no less than 28 bar (400 psi). If compression readings are below specifications, repeat step 13 with a different gauge to be certain of the reading.
Note : Fuel injector hold-down bolts are a one-time use item.
22 Remove the fuel injector hold-down clamps. Discard the hold-down bolt and remove the compression test adaptors.
23 Repeat steps for all suspect cylinders.
24 Repair engine as necessary.
More repair cases for Detroit Diesel engines,please refer to:Detroit Diesel Engine Repair
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