Product Description
Interstate-McBee M-3939258 Lift Pump Cover Plate Gasket – 89–98 5.9L Cummins (12-Valve)
Quality replacement gasket for the mechanical lift pump mounting pad on the 1989–1998 5.9L Cummins 12-valve (6BT). Use when installing a new mechanical lift pump or when sealing a block-off/cover plate during electric lift-pump conversions. Sold individually.
- Leak prevention: Seals the lift pump or block-off plate to the engine block.
- Correct fit: Matches OEM geometry for proper port alignment.
- Durable materials: Fuel-resistant construction for longevity.
- Easy install: Drop-in replacement with factory hardware.
Specifications
| Brand | Interstate-McBee |
| Part Number | M-3939258 |
| OEM Reference | Cummins 3939258 (gasket) |
| Application | Mechanical lift pump / block-off (engine block mounting pad) |
| Sold As | Each (1 gasket) |
What’s Included
- (1) Lift pump cover plate gasket, P/N M-3939258
Vehicle Fitment
Always verify by engine serial number (ESN) when possible.
- Dodge Ram 2500/3500 with 5.9L Cummins (12-valve 6BT)
- Model Years: 1989–1998
- Other B-Series applications using Cummins 3939258 at the lift-pump pad (confirm by ESN).
Recommended/Related Parts
- Mechanical lift pump (stock replacement)
- Lift pump block-off / cover plate (for electric lift-pump conversions)
- Mounting bolts and washers (reuse or replace as needed)
- Solvent and lint-free wipes for surface prep
Install Notes
- Clean both mating surfaces until free of old gasket material and residue.
- Install the gasket dry; do not over-apply sealant unless specified by the service manual.
- Torque fasteners to factory spec in an even, alternating pattern.
- After installation, prime the fuel system and inspect for seepage.
Why Buy From CPP Diesel
- ESN-verified fitment support from diesel specialists
- Fast shipping and easy returns
- Deep inventory of Cummins B-Series service parts
FAQ
Is this the gasket under the lift pump or the block-off plate?
Both. It seals the engine-block mounting pad either to the mechanical lift pump or to a block-off/cover plate used during electric pump conversions.
Do I need sealant?
Typically no—install the gasket on clean, flat surfaces and torque to spec. If your service manual specifies a light dressing, follow that guidance.
How many are required?
One gasket per engine.
