Failure mode - Cummins 5.9L Diesel (Dodge Ram HD)
Killer Dowel Pin (KDP) on the 12v P-pump engines
Reliability tier: verified - verify before ordering, see /disclosure/
Symptoms
- no warning until the pin falls: grinding/clatter from the front gear housing, then sudden engine stop or damage
- found preventively: pin protruding or missing at the front cover during timing cover service
Compare with the other causes of the same sign on this engine: stalls or dies while driving · ticking, knocking, rattle or whine (3 causes)
Root cause
The dowel pin locating the front gear housing is pressed from the inside on 1989-early-1998 12v 6BT blocks and can work loose over time, falling into the cam gear (best case: trapped by the case; worst case: through the housing into the gears). The single most famous 12v failure and the reason 'tabbing the KDP' is a rite of passage on these engines.
Diagnosis
- check the pin at any front-cover service; a borescope through the fill/fittings finds it without teardown
- brazilian fix (bending the case lip) is a field expedient, not a repair
Fixes
tab kit: bend/stake a retainer tab over the pin (the standard preventive fix, ~$10 in parts) ()
if the pin has already dropped: front gear housing removal, gear inspection and full housing reseal ()
Prevalence
common
Parts for this repair run about $220-$520: see them next to the other repairs on this engine in repair costs.