Product Description
Cummins 3901020 — Piston Cooling Nozzle / Oil Squirter (Short, ~3/4")
MPN: 3901020 | Also Known As: piston cooling nozzle, oil squirter, cooling jet | Cross-Refs (ID only): M-3901020, FP-3901020, CUM3901020
Why This Part
- ✓ OE jet that directs oil to the underside of the piston for cooling and durability.
- ✓ Common fit for early 5.9L 12V (1989–1993) plus select B/QSB industrial engines (verify by ESN).
- ✓ Short (~3/4") nozzle style used on many early engines.
- ✓ Sold individually; 6 required per engine (one per cylinder).
Quick Specs
| Type | Piston cooling nozzle / oil squirter |
|---|---|
| OE Part # | 3901020 |
| Style / Length | Short nozzle (~3/4") |
| Qty Required | 6 per engine (sold individually) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–1993 | 5.9L 12-Valve B-Series (VE) | Dodge Ram 2500/3500 |
Industrial/Off-Highway: Used primarily on early Tier-1 B3.9/QSB5.9 applications. Always confirm by Engine Serial Number (ESN) and nozzle length.
Compatibility Notes:
- Early engines may use the short style (~3/4") while later 12V/24V engines often use a different nozzle. Verify length and ESN.
- If switching to larger-orifice aftermarket jets, consider an updated oil pump to maintain oil pressure.
Often Paired With
- Engine oil pump (upgrade as needed): maintain oil pressure with higher-flow jets
- Gaskets/seals disturbed during teardown
- Fresh oil & filter after rebuild
What’s In The Box
- (1) Genuine Cummins Piston Cooling Nozzle (3901020)
- Sold individually (order 6 for a complete set)
Install Tips
- Verify nozzle length/orientation and clearances during assembly.
- Use threadlocker or new fasteners where specified; torque per Cummins procedure.
- Prime the oil system and check for leaks after first start.
FAQ
WILL THIS FIT MY 1989–1993 5.9L 12V RAM?Common early 12V fit (1989–1993). Confirm by ESN and nozzle length (short style) before ordering.
HOW MANY DO I NEED?Six nozzles per engine—one per cylinder. This part is sold individually.
WHAT’S THE DIFFERENCE BETWEEN SHORT AND LONG NOZZLES?Early engines used a short (~3/4") style; later engines may use a longer design. Always match length to your ESN and piston/rod configuration.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 3901020. Cross-references like M-3901020 or FP-3901020 indicate aftermarket equivalents.
DO I NEED TO UPGRADE THE OIL PUMP?If you move to larger-orifice aftermarket jets, an updated pump is recommended to sustain oil pressure; with OE nozzles, follow factory specs.
