Cylinder Liner Sleeve 3904166 | Verified Fitment for Cummins ISB QSB

Verified Fitment — Cross-reference data checked against Cummins B-series, ISB, and QSB engine serial ranges to lock the correct liner variant before you order.

Technical Specifications

Application Suitability

Why the Same Cylinder Liner Number Ships in Multiple Variants Across Engine Generations

A single base reference covers several physically different liners, and ordering the wrong one means the flange fails to register or the interference fit is out of tolerance.

The Cummins B-series, ISB, and QSB families evolved across multiple ECU generations (CM550, CM800, CM850, CM2150, CM2250, CM2850), and block castings changed accordingly. A Cylinder Liner 3904166 for Cummins ISB QSB cross reference fitment lookup that ignores the engine serial number will leave you guessing whether you need the standard outer diameter or the oversize variant. In the field, that mistake shows up as a liner that drops in too loose, or one that won't press into the bore at all — both resulting in a torn-down engine sitting idle while the correct part arrives [NEED_CITE: cylinder liner interference fit standards for medium-duty diesel engines]. I have seen workshops order six liners for a 6B5.9 overhaul based on a parts manual that predated a block revision, only to discover the flange counterbore depth had changed mid-production.

Engine Serial Range Coverage and Variant Identification

The fitment list spans from early 4B3.9 and B3.3 blocks through late-generation QSB6.7 CM850(CM2850) configurations. Each engine serial prefix maps to a specific block casting with defined bore dimensions and flange register geometry. A Cylinder Liner 3904166 for Cummins ISB QSB cross reference fitment inquiry starts with your engine serial number, not just the model badge. The difference between an ISB6.7 CM2250 and an ISB6.7 CM2350 B101, for example, can be a matter of outer diameter tolerance band — one block accepts the tighter Ø0.015 mm interference, while the other requires the Ø0.030 mm range. We verify the serial-to-variant mapping before confirming fitment.

Cross-Reference Verification and Superseded Number Traps

The reference table includes DS-3904166, DS3904166, DS-3904166OS, and DS3904166OS alongside the base 3904166 number. The OS suffix denotes oversize outer diameter, intended for blocks that have been line-bored during a previous rebuild. Ordering an OS liner for a virgin block results in an interference fit that is too aggressive, risking cracking during press-in. Conversely, fitting a standard liner into a previously bored block produces insufficient interference, leading to liner creep and coolant leakage under thermal cycling [NEED_CITE: engine block rebore practices and oversize liner specifications]. Cross-reference tables copied between aftermarket sellers often carry forward errors — a DS prefix dropped, an OS suffix omitted — so every number we confirm is checked against the actual dimensional requirement, not just a catalog lookup.

Material and Machining Specifications That Determine Fitment Outcome

The liner is produced from forged nodular cast iron meeting ASTM A536 Grade 100-70-03, selected for its combination of tensile strength and damping capacity under combustion loading. Bore roundness is held to ±0.005 mm, which is critical for piston ring sealing during the initial break-in period — an out-of-round bore causes localized ring wear and oil consumption that shows up within the first few hundred hours. The plateau-honed surface finish at Ra ≤ 0.8 μm provides the crosshatch pattern that retains oil film while allowing rings to seat without excessive scuffing. Vacuum impregnation seals micro-porosity in the casting, preventing coolant seepage through the liner wall into the crankcase over extended service. Post-machining stress relief eliminates residual stresses from forging and boring, reducing the risk of dimensional shift after installation.

What Happens When the Wrong Variant Gets Installed

A liner that fits loosely in the block bore will shift under thermal expansion, breaking the flange seal and allowing coolant to enter the cylinder. The first sign is usually white exhaust smoke and unexplained coolant loss, but by then the liner has already fretted against the block bore, potentially scoring the parent metal and requiring a line-bore before the engine can be rebuilt again. A liner forced into a bore with excessive interference can crack at the flange radius during press-in — a failure that may not appear until the engine reaches operating temperature and the block expands differentially [NEED_CITE: cylinder liner installation failure modes in cast iron blocks]. Either scenario means a second teardown, another set of gaskets and seals, and additional days of machine downtime.

How Fitment Certainty Works Here

We produce selected part lines in our own facility and source the remainder from qualified ISO-certified manufacturing partners, with both paths carrying identical QC and warranty terms. Eight product categories sit under one account, so a complete overhaul order — liners, pistons, bearings, seal kits — consolidates into one shipment with one set of documentation. Minimum order is one piece, which matters when you need a single replacement liner to finish a job. Our Guangzhou warehouse holds stock on fast-moving items for immediate dispatch. Part identification works from a number, a machine model, a photograph of the old liner, or even a nameplate image when the casting is too worn to read. Cross-reference verification covers superseded and alternate numbers across the full Cummins B, ISB, and QSB range. Sample units ship for fitment confirmation before you commit to a full rebuild set, and our technical team is available to confirm compatibility and dimensional grade.

Documentation & Verification

• Commercial invoice and packing list with engine serial and liner variant notation
• Part compatibility and cross-reference sheet marked reference only for all OEM numbers
• Dimensional inspection record covering bore roundness and outer diameter tolerance
• Warranty terms covering manufacturing defects for 3 to 12 months
• Packing photographs showing anti-rust oil application and individual protective packaging
• HS code and customs documentation support for cross-border shipment

Fitment Check Before Installation

• Measure block bore inner diameter at three depths to confirm which OD tolerance band applies
• Check flange counterbore depth against liner flange thickness to verify register geometry
• Compare old liner outer diameter and flange profile against the new unit side by side
• Verify liner sits flush or slightly proud per block specification before pressing fully
• If interference feels wrong during press-in, stop and remeasure — do not force installation

Requesting a Fitment Confirmation

Send the engine model, serial number, and any readable casting numbers from the old liner. If the nameplate is worn or painted over, a clear photograph of the engine block casting number and the existing liner flange marking is enough for us to cross-reference the correct variant. For fleets with mixed Cummins B-series and QSB engines, provide the full engine list so we can map each serial to its liner requirement and flag any blocks that have been previously rebored.

Frequently Asked Questions

Q: How do I confirm which liner variant fits my specific Cummins engine serial number? A: Provide your full engine serial number, including the prefix. We cross-reference it against block casting records to identify the correct outer diameter tolerance band and flange geometry. This is essential because the same base reference covers multiple physical variants across the B-series, ISB, and QSB families.

Q: The old liner has a different number — can I still use 3904166 as a replacement? A: Possibly, but it depends on whether the old number is a superseded reference or a variant from a different production run. Send us both numbers and we will verify the cross-reference against dimensional data, not just catalog listings that may carry forward errors.

Q: What is the difference between standard and OS oversize liner references? A: OS-designated liners have a larger outer diameter intended for blocks that have been line-bored during a previous rebuild. Installing an OS liner in a virgin block risks cracking during press-in. We confirm which size your block requires based on bore measurement.

Q: I only have the engine model, no readable part number — can you still identify the correct liner? A: Yes. Send the engine model and serial number, or a photograph of the block casting number. We use those to trace the correct liner variant even when the old part is too worn or painted over to read.

Q: Can I order a sample to verify fitment before committing to a full engine rebuild set? A: Yes, samples ship individually so you can confirm bore fit, flange register, and dimensional accuracy on your block before ordering the complete liner set for a multi-cylinder overhaul.