2013-2018 Ram 2500 & 3500 6.7L Cummins Timing Cover Oil Leaks Explained

Diagnosing Front Engine Oil Leaks

An oil leak at the front of the 6.7L Cummins engine in a 2013-2018 Ram 2500 or Ram 3500 can be alarming, and proper diagnosis is key to a correct and cost-effective repair. The source of the leak is often misdiagnosed, leading to repeat repairs. There are three primary sources for an oil leak in this area, ranging from a simple fix to a major engine-out service.

1. Front Crankshaft Seal Leak

This is the most straightforward and common type of leak. The rubber seal that sits inside the timing gear housing and seals against the spinning crankshaft harmonic balancer can wear out over time. A leak here will appear as oil slung around the front of the engine bay in the path of the spinning balancer and will drip from the bottom of the balancer itself. 🎬 Watch: Step-by-step guide to replacing the front main seal. This is the easiest of the three potential leaks to fix.

2. Outer Timing Cover Gasket Leak

The 6.7L Cummins has a multi-piece front cover assembly. The outermost piece is a stamped steel cover. The gasket behind this cover can fail, causing a leak. While more involved than a crank seal, this is still a manageable repair that does not require extensive engine disassembly.

3. Inner Gear Housing Gasket Leak

This is the most severe and costly leak. The main cast aluminum gear housing bolts directly to the engine block, with a large gasket sealing the two. When this gasket fails, oil weeps from the seam between the housing and the block. It's often mistaken for a front crank seal leak, but the oil originates higher up, often near the top of the housing. 🎬 See how to identify a leaking inner timing gear housing. Repairing this gasket is a massive job, as the camshaft must be removed to access the housing bolts.

Known Issues, TSBs, and Recalls

The "Killer Dowel Pin" Myth

Many Cummins enthusiasts are aware of the "Killer Dowel Pin" (KDP) issue, where a small alignment pin could back out of the block and fall into the timing gears, causing catastrophic engine failure. It is important to know that this issue only affected pre-2002 5.9L Cummins engines. The 2013-2018 6.7L Cummins engine does not have this problem, and no preventative action is needed.

Technical Service Bulletins (TSBs)

While no major recalls exist for this specific part, some technicians have reported an informal TSB regarding the bolts for the timing gear housing. The issue suggests that the original factory torque specification may not have provided enough clamping force on the gasket, leading to leaks over time. The reported fix involves using new bolts with a higher torque rating during reassembly to ensure a durable seal.

Buying a Used Timing Cover: What to Inspect

A used OEM timing gear housing is a great way to save money, especially since new aftermarket versions can be of questionable quality. Before purchasing a recycled part, perform a thorough inspection:

• Check for Cracks: Carefully inspect the entire housing, especially around the bolt holes and any sharp corners, for hairline cracks. A crack renders the part useless.
• Inspect Sealing Surfaces: Lay a straight edge across all machined sealing surfaces (where the cover meets the block and where the outer cover bolts on). Look for any signs of warping or low spots that could prevent a good seal.
• Examine the Crank Seal Bore: Look at the machined opening where the front crankshaft seal is installed. It should be smooth and free of deep scratches, gouges, or corrosion that would prevent the new seal from seating properly.
• Verify Part Numbers: Ensure the part number on the used housing matches the required OEM number for your vehicle. The primary part number is 68453903AA, which replaces the earlier 68210069AA.

Replacement Cost Comparison

Engine Timing Cover Replacement Overview

• Difficulty Rating: 2/5 (for outer seal/cover) to 5/5 (for inner housing gasket)
• DIY Feasibility: Replacing the outer seal is possible for an experienced DIYer. Replacing the inner housing gasket is not recommended for DIY repair due to its complexity.
• Procedure Notes: The inner gasket replacement is one of the most intensive repairs on this engine. It requires removing the fan, radiator, harmonic balancer, all front accessories, valve cover, rocker arms, pushrods, and pulling the camshaft forward out of the block to access the housing bolts. This is why labor costs are extremely high.

Frequently Asked Questions (FAQ)