Artie’s Answers: The 12-Valve Killer Dowel Pin

Every make and model in some way, shape, or form have their quirks or issues. Some complications are serious, but others aren’t near as urgent. As diesel enthusiasts, you all have heard of the Killer Dowel Pin, often referred to as the KDP. The “Killer Dowel Pin” is a concern on 1989 to 1998.5 12-valve Cummins engines.

This is a steel pin that’s pressed into the cast iron block. What the pin does is perfectly aligns the aluminum timing gear housing to the engine during assembly. The problem with the dowel is that with the vibration of the engine, it eventually can come out of its socket. With that being said, you risk compromising your engine.

The dowel has come loose and lodged between the case and the gear and as you can see, the case is compromised.

One of three options can occur when and if this dowel comes out. First, the pin can come out and bounce off the cam gears and just end up in the bottom of the timing gear housing causing no damage. Secondly, the pin can come out and forced into the timing gear housing, cracking the case before egress to the outside air.

Thirdly, the worst case scenario, the pin comes loose and becomes embed between the timing gears which leads to a catastrophic failure. If that does happen, the pistons will contact the valves in the cylinder head and the engine will basically self-destruct.

As you can see, someone has torn the front cover down for the repair. You can see that there is nothing securing the dowel which has the possibility to come out.

Many companies offer a repair kit for this somewhat common disaster. The kit comes with the new dowel pin with a teardrop-shaped bracket attached that’s threadable and will keep the pin secure on the block. While being inexpensive, the job does require some more than normal labor. You’re required to pull most of the components of the front of the engine to reach the timing gear housing.

Most kits will obtain the new tab, the dowel, front crank seal, and a timing gear case gasket.

Frequently truck owners will argue that there is a small chance that this could even happen, but for the minimum investment and a day of work, it seems to be worth the insurance. For more information on DIY or how-to articles, stay tuned to Diesel Army.

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About the author

Artie Maupin

Artie Maupin is from Southeast Missouri and has an extreme passion for anything diesel. He loves drag racing of all kinds as well as sled pulling competitions.
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