5.9L Cummins Killer Dowel Pin (KDP)

12v Cummins KDP Information, Problem Prevention

The "Killer Dowel Pin", as it is so infamously named, refers to a small metal dowel inserted into the engine block that is used to align the front gear housing during initial assembly. It is located above the camshaft gear and to the left (looking at the front of the engine) of the injection pump gear. The KDP is amply named because it can have catastrophic consequences if it dislodges and descends down the front cover. While this pin is found on 12v (6BT) and 24v (ISB) 5.9L Cummins engines, problems associated with dislodging are generally limited to 12v engines found in 1989 to 1998 model year trucks, and, for inconclusive reasons, most prolific on 1994 to 1998 model year trucks.

Cracked camshaft gears and/or cracked gear housings are amongst the most common failure points when a KDP becomes dislodged and begins dancing around the complex system of gears keeping the engine running in sync. The best scenario following a KDP event is that the dowel pin gently falls to the bottom of the front cover, eventually settling [peacefully] at the bottom of the oil pan where it can rest indefinitely without concern (a screen on the oil pump eliminates the possibility of damage occurring should the pin find its way into the oil pan). The worst case scenario is that the dowel pin becomes lodged between the camshaft and injection pump gears, causing a chain reaction of destruction that includes the pistons meeting the valvetrain and ultimately a catastrophic, unrepairable engine failure.

While affecting all 12v engines, KDP related failures are most common on 1994 to 1998 model year trucks, which utilize the Bosch P1700 injection pump. The [more desirable] P-pump engines are thought to experience different harmonics in the gear train and front cover assembly than 1989 to 1993 engines equipped with the VE44 rotary injection pump. Due to the potentially hazardous nature of the KDP, we highly recommend installing a KDP prevention tab on all 12v engines to permanently eliminate any and all concerns.

KDP Tab/Eliminator Kit Information

A KDP prevention kit is relatively inexpensive insurance against the possibility of a premature, catastrophic engine failure. It works by installing a small metal tab over the dowel pin using an adjacent bolt that secures the gear housing to the engine block. Installation of the tab is simple, straight forward, and intuitive. However it requires removal of the front cover, a relatively invasive and time consuming process for first timers. In reality, the procedures are much more intimidating than they are difficult. Some KDP kits include a replacement front cover gasket, while more affordable solutions reseal the front cover using RTV silicon. There is some evidence to suggest that using RTV silicon is advantageous to the factory replacement gasket and may provide a more resilient seal in certain instances.

For 1994 - 1998 model year Dodge Rams equipped with the 12v Cummins, we highly recommend the following the kit: 12v Cummins KDP Tab & Complete Installation Kit

KDP dowel pin location on 12v Cummins diesel

Killer dowel pin (KPD) location identified by arrow.
With the front cover removed from the engine, the KDP is easily accessible.

Closeup view of dowel pin (KDP) on 5.9L Cummins diesel

Close up of alignment dowel. The adjacent bolt is removed and used to secure the KDP tab.

5.9L Cummins 12v diesel with KDP tab installed, preventing dowel pin dislodging

KDP tab installed, permanently preventing the alignment dowel from dislodging.