Product Description
Genuine Cummins
Cummins 3912087 — Inner Heater Tube (Near Valve Cover) for 5.9L 12V
MPN: 3912087 | Also Known As: vehicle heater tube, heater hard line | Position: Inner (nearest to valve cover)
Why This Part
- ✓ OE formed steel hard line for correct routing and leak-free sealing.
- ✓ Direct-fit for 1989–1998 Dodge Ram 5.9L 12V Cummins.
- ✓ Restores proper heater core coolant flow and cabin heat performance.
- ✓ Factory geometry to clear brackets, wiring, and accessories.
OE Fit Stock Replacement 1 Per Vehicle
Quick Specs
| Type | Vehicle heater tube (engine-to-heater hard line) |
|---|---|
| OE Part # | 3912087 |
| Position | Inner — nearest to valve cover (pairs with Outer tube 3912086) |
| Qty Required | 1 per vehicle (sold individually) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–1998 | 5.9L 12-Valve B-Series Cummins (1st & 2nd Gen) | Dodge Ram 2500/3500 |
Notes: This is the inner hard line nearest to the valve cover. The matching outer line near the fender is Cummins 3912086.
Often Paired With
- Outer Heater Tube: Cummins 3912086 (near fender)
- Heater Hoses & Clamps: replace aged rubber for best sealing
- Coolant: refill/bleed system after service
What’s In The Box
- (1) Genuine Cummins Inner Heater Tube (3912087)
- Hoses/clamps/brackets sold separately (see “Often Paired With”).
Install Tips
- Drain/contain coolant below tube level; save for reuse if clean.
- Use new hose clamps; route exactly per factory to avoid chafe.
- Refill and bleed the cooling system; check for leaks on warm-up.
FAQ
WILL THIS FIT MY 1989–1998 5.9L 12V CUMMINS RAM?Yes—3912087 is the inner heater tube (near valve cover) for 1989–1998 5.9L 12V Ram 2500/3500.
WHAT’S THE DIFFERENCE BETWEEN 3912087 AND 3912086?3912087 is the inner tube (near valve cover). 3912086 is the outer tube routed near the fender.
DOES THIS INCLUDE HOSES OR CLAMPS?No—this listing is the hard line only. Use fresh heater hoses and clamps during install.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 3912087 for proper fit, routing, and durability.
DO I NEED TO DRAIN THE COOLANT?Partially drain the system below the line level, replace the tube, then refill and bleed per service manual.
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