The APDTY 015921 gear-driven mechanical vacuum pump is a direct-replacement part for 1994-2002 Dodge Ram 2500 and 3500 pickups equipped with the Cummins 5.9L diesel engine. This pump generates the vacuum pressure needed for proper brake booster operation, replacing OE part numbers 4746706, 5019734AA, R5019734AA, 3937193RX, and 4874365. When this pump fails, drivers experience hard brake pedal feel and reduced braking assist.
Key Takeaways
- Fits 1994-2002 Dodge Ram 2500 and 3500 pickups with Cummins 5.9L diesel engine only
- Replaces OE part numbers 4746706, 5019734AA, R5019734AA, 3937193RX, and 4874365
- Gear-driven mechanical design provides vacuum for brake booster operation
- Symptoms of failure include hard brake pedal, loss of power assist, and increased stopping distance
- Direct bolt-on replacement requiring basic hand tools and gasket replacement
Buy APDTY 015921 directly from APDTY
What Does the Vacuum Pump Do on a Cummins Diesel?
Diesel engines do not generate manifold vacuum like gasoline engines, because they operate without a throttle plate. The mechanical vacuum pump solves this problem by creating the vacuum pressure required to operate the brake booster. This pump is gear-driven off the engine's accessory drive system and runs continuously whenever the engine is operating.
The brake booster uses vacuum to multiply the force applied to the brake pedal, allowing normal braking effort to produce sufficient hydraulic pressure for safe stopping. Without adequate vacuum, the brake system still functions, but the driver must apply significantly more pedal force to achieve the same braking power.
What Are the Symptoms of a Failed Vacuum Pump?
A failing or failed vacuum pump on your Cummins 5.9L diesel produces several noticeable symptoms:
- Hard brake pedal: The most common symptom is a stiff, difficult-to-press brake pedal requiring excessive leg force
- Loss of power assist: Braking feels manual or unassisted, especially noticeable when starting from a stop
- Increased stopping distance: Without vacuum assist, achieving full braking force requires more pedal travel and pressure
- Hissing or squealing noises: A failing pump may produce audible noise from worn internal gears or seals
- Vacuum leaks: Oil seepage around the pump housing or connections indicates seal failure
- Check engine light: Some vehicles may store diagnostic codes related to insufficient vacuum pressure
If you notice any of these symptoms, the vacuum pump should be tested and replaced if defective. Driving with a failed pump is possible but significantly reduces braking safety and increases driver fatigue.
Which Vehicles Does APDTY 015921 Fit?
According to verified product fitment data, the APDTY 015921 vacuum pump is compatible with the following vehicles:
| Year Range | Make | Model | Engine Required |
|---|---|---|---|
| 1994-2002 | Dodge | Ram 2500 Pickup | Cummins 5.9L Diesel |
| 1994-2002 | Dodge | Ram 3500 Pickup | Cummins 5.9L Diesel |
Important: This pump fits ONLY Dodge Ram 2500 and 3500 pickups with the Cummins 5.9L diesel engine manufactured between 1994 and 2002. It does NOT fit gasoline engines or other diesel configurations. Always verify your specific vehicle compatibility using the fitment chart on the product page before ordering.
OE Part Numbers and Specifications
The APDTY 015921 replaces the following original equipment manufacturer part numbers:
| OE Part Number | Notes |
|---|---|
| 4746706 | Primary Mopar/Chrysler number |
| 5019734AA | Updated Mopar replacement number |
| R5019734AA | Remanufactured variant designation |
| 3937193RX | Earlier service part number |
| 4874365 | Cross-reference service number |
Product Specifications:
- Type: Gear-driven mechanical vacuum pump
- Drive Method: Engine accessory gear driven
- Application: Brake booster vacuum generation
- Condition: Brand new (not remanufactured)
- Mounting: Direct bolt-on replacement
How to Install a Vacuum Pump on Cummins 5.9L Diesel
Replacing the vacuum pump on a 1994-2002 Dodge Ram with Cummins 5.9L diesel is a straightforward procedure that most DIY mechanics can complete with basic hand tools. Note: This is a general overview; always consult a factory service manual for your specific model year and follow all safety procedures.
Tools and supplies needed:
- Socket set and wrenches
- Screwdrivers
- Gasket scraper or razor blade
- New mounting gasket (recommended)
- Clean rags and brake cleaner
- Torque wrench
General installation steps:
- Disconnect the battery: Remove the negative battery cable to prevent accidental electrical contact
- Access the pump: Locate the vacuum pump mounted to the engine block or timing cover; you may need to remove air intake components or other obstructions for clearance
- Disconnect vacuum lines: Remove the vacuum hose(s) connected to the pump outlet, noting routing for reinstallation
- Remove mounting fasteners: Unbolt the pump from its mounting location using appropriate sockets
- Remove old pump: Carefully pull the pump away from the engine; the drive gear will disengage as you remove it
- Clean mounting surface: Thoroughly clean the mounting flange on the engine block, removing all old gasket material
- Install new gasket: Position a new mounting gasket on the engine (if your pump does not include one, obtain the correct gasket separately)
- Install new pump: Align the pump drive gear with the engine drive gear and carefully slide the new pump into position
- Torque fasteners: Install and torque mounting bolts to factory specifications in a cross-pattern
- Reconnect vacuum lines: Reattach vacuum hoses securely, ensuring no kinks or damage
- Reconnect battery: Reinstall the negative battery cable
- Test operation: Start the engine and verify proper brake booster function with a firm brake pedal
After installation, monitor the pump for leaks during the first few drives and verify that brake assist is functioning normally. If the brake pedal remains hard after installation, check for vacuum leaks in the hoses or connections between the pump and brake booster.
Frequently asked questions
Will APDTY 015921 fit my 2003 or newer Dodge Ram with Cummins diesel?
No. This vacuum pump is verified to fit only 1994-2002 Dodge Ram 2500 and 3500 pickups with Cummins 5.9L diesel. Later model years use different pump designs. Always check the compatibility chart on the product page for your specific vehicle.
Do I need to replace the gasket when installing a new vacuum pump?
Yes, it is strongly recommended to replace the mounting gasket during installation. Reusing the old gasket can result in vacuum leaks or oil seepage, which will compromise pump performance and cause return of the original hard brake pedal symptom.
Can I drive my truck if the vacuum pump fails?
Technically yes, but it is not recommended. The brakes will still function, but without power assist you must apply much greater pedal force to stop the vehicle. This significantly increases stopping distance and driver fatigue, creating a safety hazard especially in emergency braking situations.
What OE part numbers does APDTY 015921 replace?
APDTY 015921 replaces Mopar/Chrysler OE part numbers 4746706, 5019734AA, R5019734AA, 3937193RX, and 4874365. You can cross-reference any of these numbers to confirm fitment for your vehicle.
If your 1994-2002 Dodge Ram 2500 or 3500 with Cummins 5.9L diesel is experiencing a hard brake pedal or loss of braking assist, the APDTY 015921 vacuum pump provides a direct-replacement solution. This gear-driven mechanical pump restores proper vacuum pressure for safe, effortless brake operation. With verified fitment for the specified model years and diesel engine, and compatibility with multiple OE part numbers including 4746706 and 5019734AA, this pump offers a reliable fix for one of the most critical safety systems on your truck. Check the fitment chart to confirm compatibility with your specific vehicle, and restore confident braking performance today.