Determine the exact oversize single copper sealing ring required after injector seat reaming (Black Death repair) or cylinder head skimming to maintain factory nozzle protrusion geometry.
Standard factory copper washer thickness before machining
Material removed from the injector well bottom with a seat cutter to clean carbon blow-by erosion
Material milled from the cylinder head deck surface during resurfacing
When checked, head skimming does not alter nozzle-to-piston clearance; only seat reaming depth is added to the copper washer.
Stacking two washers (e.g. 1.50 mm + 0.50 mm) creates an interfacial thermal barrier that blocks heat transfer from the nozzle tip to the cylinder head water jacket, causing nozzle needle seizure and rapid blow-by leakage.
If a seat is reamed by 0.40 mm and a standard 1.50 mm washer is fitted, the nozzle protrudes 0.40 mm deeper. The 1800+ Bar fuel jet strikes the piston bowl rim instead of swirling inside the chamber, melting a hole in the piston crown.
On profiled or stepped washers (such as Denso or PSA DV6), always orient the bevelled/chamfered edge or raised crush ring according to the OEM manual. Always coat the injector body (not the nozzle holes) with ceramic anti-seize paste.
| Washer Thickness | Primary Workshop Application | Typical Bosch / Cargo / OEM Ref | Availability |
|---|---|---|---|
| 1.50 mm | Standard factory fitment (Bosch CRI / Delphi) | Bosch F 00V C17 503 | Standard OEM |
| 1.55 mm | Mercedes-Benz CDI standard factory thickness | A 611 017 00 60 / F 00V C17 504 | Standard OEM |
| 1.70 mm (+0.20) | Light injector seat resurfacing / carbon cleanup | Cargo 138340 / Bosch Oversize | Common Stock |
| 1.90 mm (+0.40) | Moderate blow-by erosion repair after seat cutting | Cargo 138342 | Common Stock |
| 2.00 mm (+0.50 / Std) | Standard for PSA/VAG/Denso, or +0.50 mm oversize for Bosch | Bosch F 00V C17 505 / 1981.85 | Universal Stock |
| 2.50 mm (+1.00 / +0.50) | Heavy seat salvage or +0.50 mm oversize for 2.00 mm systems | Cargo 136222 / Heavy Repair | Specialist Stock |
| 3.00 mm (Max Salvage) | Extreme seat salvage on 2.00 mm base systems | Cargo 138345 | Specialist Stock |
Incorrect copper washer thickness alters nozzle protrusion into the piston bowl, causing incomplete combustion, cylinder misfires, and carbon buildup:
Spray angle collision with cylinder head causes cold misfire
Poor spray atomization increases soot loading in intake & EGR
Exhaust gas leakage around unsealed washers bleeds drive energy
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