IK1200309 - 2000-2003 DT466/530 Piston Pin Boss Scuffing

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Title: 2000-2003 DT466/530 Piston Pin Boss Scuffing
Applies To: DT466/530 Engine Ser# 1,194,039 through 2,000,000

Description
Piston scuffing in the subject engines can occur when the piston pin boss contacts the cylinder
liner creating localized hot spots on both the piston and the liner. The root cause has been
determined to be due to lack of piston clearance and or lubrication in the area of the piston
pin. Once minor scuffing occurs between the piston and liner the local heating due to friction
compounds the problem leading to more severe scuffing of the piston skirt.
This iKnow article covers diagnosis, recommended repair procedures and parts replacement.

Failure mode and progression:
The piston scuffing experienced on subject engines begins when there is contact between the piston pin boss
and the cylinder liner (fig 1). Warranty data on this failure shows that the engine may run for more than
100,000 miles before the failure occurs. Analysis has shown that piston scuffing is influenced by cylinder wear
in the lower piston ring turn around area.
This failure can be accelerated by insufficient lubrication. Care
should be taken to follow the recommended oil change intervals.

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IK1200309 - 2000-2003 DT466/530 Piston Pin Boss Scuffing

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Figure 1 - Pin boss areas
Contact between the piston and liner creates localized hot spots on both the piston and the liner which
progressively make the contact worse until severe scuffing of the piston skirt occurs (fig. 2).

Figure 2 - Pistion from failed cylinger
When piston skirt scuffing reaches this point, audible engine knocking will occur, which is the overt indication of
the failure. Continued operation of the engine in this condition will lead to heat failure of the cylinder liner to
block seal which, in turn, allows coolant to enter the crankcase resulting in engine overheating and further
engine damage.

Diagnostic Procedures:

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An engine with suspected piston scuffing can be diagnosed as follows:
1. Engine knock when running.
2. Coolant in crankcase
3. Evidence of, or driver complaint of, engine overheating
4. Clear evidence of engine oil degradation i.e. high viscosity, excessive soot in oil.

5. One severly scored cylinder with additional cylinders that exhibit pin boss scoring. When there is no
evidence of pin boss scoring it is most likely the cause of failure is something else. Care should be taken to
investigate for other causes including cooling system overheating.
Confirm scuffed cylinder liner by inspecting each cylinder by first removing the oil pan, then rotate engine so
that pistons #1 and #6 are at the top of their stroke. Look for evidence of scoring or vertical scratches on the
cylinder liners (fig. 3 and 4). Repeat the process for cylinders #2 and #5 and finally cylinders #3 and #4.

Figure 3 - Light scuffing adjacent to pin boss area in lower liner

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Figure 4 - Heavy scoring on failed cylinder

Repair Procedure:
Installation of a Works Overhaul Kit is usually required to insure a robust and lasting repair. Works kits supplied
after November 1, 2007 include redesigned pistons with additional clearance in the pin boss area to help
prevent future failures.
Once the cylinder head has been removed from the engine a closer examination of the scuff damage will reveal
the extent of the failure. When piston/liner pin boss scuffing is found it is recommended that all six pistons and
liners be replaced. Any evidence of piston pin boss scuffing/scoring with the cylinder liner is cause for
replacement. See figure 1.
When a works kit is utilized for the repair please keep in mind that the mission is to replace pistons and cylinder
liners to alleviate the fail mode. The cylinder head, for example, is not associated with piston scuffing and may
remain in good serviceable condition. Total reconditioning of the head, just because it off the engine, can
unnecessarily add to repair cost. In that light, the following list describes the service operations deemed
appropriate for engines exhibiting piston scuffing :
1. Replace pistons, piston pins, rings, cylinder liners and liner seals.
2. Replace connecting rod bearings.
3. Inspect the lower shell of the center main bearing for damage or excessive wear. Only replace main
bearings if needed. NOTE: Main bearing replacement is not included as part of the piston scuffing repair.
4. Inspect cylinder head for obvious defects or excessive wear. This could include valve tips, valve springs,
rocker arms. NOTE: Cylinder head reconditioning is not included as part of the piston scuffing repair.
5. Inspect turbocharger compressor and turbine blades for evidence of foreign object damage. Inspect VGT
vanes for excessive corrosion and free operation. NOTE: Turbocharger reconditioning is not included as
part of the piston scuffing repair.
6. Inspect exhaust manifold for cracks or damage. NOTE: Replacement is not included as part of piston
scuffing repair.
7. Inspect cooling system for obstruction and signs of leakage. Replace coolant, coolant conditioner and
coolant filter (if so equipped). NOTE: Cooling system repairs are not included as part of the piston scuffing

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repair.
8. Once the repair is completed, change engine oil and filter again after 1 hour of running only if evidence of
coolant in crankcase was present during disassembly.
9. Check condition of air filter elements. Service air cleaner assembly if required before returning the unit to
customer service. NOTE: Air cleaner servicing is not included as part of the piston scuffing
repair.Recommended Parts Replacement:

The following list describes approved parts for the piston scuffing repair:
 Pistons and wrist pins*
· Piston rings*
· Cylinder liners*
· Cylinder liner seals*
· Bearings, connecting rod*
· Bearings, crankshaft mains* (optional)
· Oil filter*
· Gaskets, o-rings and seals*
· Coolant filter

* Included in Works Kit
It is unlikely that other components or extended repairs will be a result of the piston scuffing failure. These
circumstances must be approved on case by case basis by the customer.

Additional Failure Modes for Subject DT 466E/530E:
Piston pin boss scoring is only one of numerous failure modes that require replacement of piston/liners. It is
important that care be taken to identify the correct failure mode to insure proper repair. Some additional failure
modes are listed below however this list is not intended to be all inclusive.
Piston and Cylinder Liner Scoring:


Engine overheating
- Coolant loss
- Defective water pump
- Restricted radiator
- Fan or fan drive malfunction



Loss of lubrication

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- Lack of engine oil
- Poor oil quality or lack of maintenance and/or regular oil change intervals
- Worn or defective oil pump
- Oil pressure regulator malfunction
- Loss of oil pressure due to leakage or worn bearings


Engine over speed



Foreign object damage



Failed valve spring



Loose valve seat in head



Failed Injector
- Broken tip
- Over fueling
- Dry fire, improper priming of fuel system



Excessive combustion temperature
- Fuel rate too high

Dusted Engine:


Poor maintenance of induction system
- Lack of filter element service, primary and secondary
- Incorrect re-assembly of air cleaner components
- Loose hose connections between air cleaner and turbocharger compressor inlet

Damaged or leaking hoses and pipes between air cleaner and turbocharger compressor inlet
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