When it comes to diesel-truck lore, there are few things that are more aptly named than Killer Dowel Pin Syndrome. It's a problem that was initially reported on Dodges with the Cummins 5.9L from '89-'98 1/2 and is something that can have catastrophic results. During engine assembly, a steel dowel pin is pressed into the block to precisely locate its timing-gear housing. The problem? Over time, vibration can cause the pin to work its way out, and because it's made of steel, there is no working its way through the engine. It becomes the dowel pin of death.
There are a few things that can happen. Option number one: you get extremely lucky and the pin falls through the maze of cam, crank, and injection-pump gears and lands harmlessly in the oil pan or on the bottom of the gear housing-and nothing happens. Total cost for repairs: $0.
Option number two: the pin falls, and it comes in contact with the cam gear and smashes into the gear housing on the front of your engine. When this happens, it is steel versus aluminum-and steel wins out. The housing will crack open or lose a big chunk right where the dowel pin was forced into the housing. If this happens, you'll wake up the next morning and notice the Exxon Valdez in your driveway. Your total repair bill, including labor, will be approximately $1,000.
Option number three is the killer: the pin falls and munches up the cam gear or breaks it off completely. The valves will then smack into the pistons, creating a junkyard in your combustion chambers. Scraping metal doesn't work nearly as well as #2 diesel, and this can take out your heads, valves, and pistons-and possibly your engine block, making it impossible to overbore and rebuild. If this happens, there are almost no parts you can salvage, and your only option is to either to sell the truck for parts or pick up a new engine to the tune of at least a few thousands bucks. When option number three happens, you'll be left stranded on the side of the road.
This is what you'll be up...
This is what you'll be up against to access the dowel pin. The fan, shroud, belt, tensioner, oil-filler tube, crank-position sensor, crank pulley, and harmonic balancer will all need to come out before you can take the gear cover off. You might have to make a few trips to the hardware store to buy tools if you decide to tackle the project yourself.
Our '97 Dodge Ram cost $5,000, and we were really worried about option number three because we knew buying another truck might be a cheaper option than getting it fixed. While it may only happen to a few percent of Dodges, the killer dowel pin (KDP) can strike at any time, which is a huge worry for those using the truck for a business or driving long distances.
There are a dozen companies out there selling KDP repair kits (approximately $50) that consist of a new bolt, gaskets, and a tab to hold in the dowel pin so it can't work loose. The labor involved takes about two to three hours for a shop or about an afternoon if you are mechanically inclined and can do the repair in your driveway.
Basically, you have to remove all accessories from the front of your engine so you can get your timing-gear cover off, put in the dowel-retaining tab, then put everything back on. It's labor-intensive but certainly not too difficult. We meant to do this ourselves, but the narrow streets of Venice, California, are the only space we have to work on our truck. Finally, we realized that $200 of shop labor was better than the total loss of the truck and took it to Redline Diesel Performance in Corona, California, to have the dowel pin fixed. Now we can sleep at night.
 The killer-dowel-pin repair...  The killer-dowel-pin repair kit consists of a gear-cover gasket, a new crank seal, and a KDP tab (arrow). Most kits also come with installation instructions; our kit from Piers Diesel Research had instructions that were accurate and well-written. |  First, drain some coolant...  First, drain some coolant out so the upper radiator hose can be removed and the fan and shroud can be taken off. Later, this can be reused as long as you store it in something clean. |  This is what needs to be removed...  This is what needs to be removed to access the KDP. It's not too difficult, but there is labor involved. |