21309 Mercruiser SLEEVE, CHOKE PIPE TO CHOKE OVEN CONNECTOR NUT

Probable Causes
Turbocharger
Valve guide seals
Valve guides
Piston rings
Extended idle timesRecommended Actions
Note: After the repair has been made, the oil should be cleaned from the exhaust system. To clean the oil from the exhaust system, perform the following procedure:
Remove excess oil from piping with a clean cloth.
Operate the engine at high idle for 10 minutes.
The max engine speed in park or neutral will be 1000 RPM.If smoke dissipates, return machine to work.If blue smoke persists, the blue smoke is an indication of a saturated aftertreatment system, perform the following procedure:
Shut off the engine.
Remove the Diesel Oxidation Catalyst (DOC) bricks, let the DOC bricks drain on the outlet side overnight.
Once drained, reinstall the DOC bricks.
Operate the engine at high idle for 10 minutes.If blue smoke dissipates, return machine to work.If blue smoke does not dissipate, Contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).
Table 1
Troubleshooting Test Steps Values Results
1. Inspect for Failed Turbocharger Seals
A. Check the following components for oil:
- Inlet manifold
- Exhaust manifold
Turbocharger Seals
Result: Oil from the turbocharger is not present in the inlet or exhaust manifold.
Proceed to Test Step 2.
Result: Oil from the turbocharger is present in the inlet or exhaust manifold.
Repair: Replace the turbocharger.
If the problem is not resolved, proceed to Test Step 2.
2. Inspect the Valve Guide Seals
A. Check the valve guide seals for the following:
- Damage
- Wear
Valve Guide Seals
Result: The valve guide seals are not damaged.
Proceed to Test Step 3.
Result: The valve guide seals are damaged.
Repair: Replace the valve guide seals.
If the problem is not resolved, proceed to Test Step 3.
3. Inspect the Valve Guides
A. Check the valve guides for wear. Refer to the Specification manual for the maximum permissible wear of the valve guides.
Valve Guides
Result: The valve guides are not worn.
Proceed to Test Step 4.
Result: The valve guides are worn.
Repair: If necessary, recondition the cylinder head. Verify the repair.
If the problem is not resolved, proceed to Test Step 4.
4. Inspect the Piston Rings
Damaged pistons or rings can cause too much pressure in the crankcase. This condition will cause the engine to run rough. There will be more than the normal quantity of fumes (blowby) entering the OCV system. The OCV system can then more quickly become restricted, causing oil leakage at gaskets and seals that would not normally have leakage. Blowby can also be caused by worn valve guides or by a failed turbocharger seal.
A. To determine whether the piston rings leak, measure the crankcase blowby. Use the following service tools, along with Software License, NETG5044:
- 285-0901 Blowby Tool Gp (LARGE ENGINE)
- 348-5430 Multi-Tool Gp
Reference Special Instruction, REHS7857 for additional information on how to measure the blowby.
Piston Rings
Result: The piston rings are not worn.
Proceed to Test Step 5.
Result: The piston rings are worn.
Repair: Replace the piston rings.
If the problem is not resolved, proceed to Test Step 5.
5. Check for Extended Idle Times
Note: Extended idle times will allow oil to pass into the exhaust system.
Idle Times
Result: The idle times are extensive.
Repair: Reduce the idle times.
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).