Product Description
Interstate-McBee M-3900068 — 14 mm Main Bearing Cap Dowel — 1989–2018 5.9L / 6.7L Cummins (Aftermarket Replacement)
Precision 14 mm alignment dowel for the main bearing cap on Cummins B-Series 5.9L (12V/24V) and 6.7L engines. Helps ensure accurate main cap location and crankshaft bore alignment during assembly. Sold individually.
- Accurate alignment: Restores factory main cap positioning to protect main bore geometry.
- Quality construction: Manufactured to OE-equivalent material and dimensional standards.
- Service ready: Ideal for engine rebuilds or when original dowels are worn, damaged, or missing.
Specifications
| Brand | Interstate-McBee |
| Part Number | M-3900068 |
| Type | Main bearing cap alignment dowel |
| Diameter | 14 mm |
| Sold As | Each (1 dowel) |
| Finish | As-machined |
Vehicle / Engine Fitment
Always verify by engine serial number (ESN) and parts catalog before ordering.
- Cummins B-Series 5.9L (1989–2007) — 12-valve & 24-valve applications
- Cummins 6.7L (2007.5–2018) — select applications using 14 mm main cap dowels
What’s Included
- (1) Main bearing cap dowel — 14 mm — P/N M-3900068
Recommended / Related Parts
- Main bearing set (standard or oversize — match to crank/bore)
- Main cap bolts or studs (replace torque-to-yield fasteners as required)
- Rear main seal & front crank seal
- Assembly lube & threadlocker where specified
Install Notes
- Clean block and cap bores thoroughly; remove burrs and corrosion before installation.
- Press or tap dowel in straight using proper support to avoid distorting the bore.
- After dowel installation and cap torquing, check main bore alignment per service manual.
- Follow Cummins torque specs and sequence; replace any damaged fasteners.
FAQ
How many dowels does my engine need?
Quantity can vary by block/cap design. Inspect your engine during teardown to match the original count and locations. This listing is per dowel.
Is this the correct size for all 5.9L/6.7L engines?
This is a 14 mm dowel. Some engines use different sizes. Confirm diameter and ESN before ordering.
Do I need to line-hone after replacing dowels?
If caps are disturbed or replaced, a line-bore/hone check is recommended to ensure main bore alignment meets specification.
