Common Diesel Engine Problems and Solutions

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Diesel engines are workhorses, powering everything from trucks to heavy machinery. However, like any complex machinery, they can encounter problems. Let’s explore some of the most common issues and their solutions:

Diesel Engine-Specific Problems:

Diesel Engine Overheating:

• Causes:
  • Engine overheating can occur when the engine is pushed too hard.
  • Engine cooling systems on the fritz prevent enough coolant from circulating the engine.
    • Faulty, clogged, or leaky radiator.
    • Damaged or blocked engine coolant lines.
  • A faulty thermostat could be misreading the engine temp, throttling back the engine coolant from the engine.
• Consequences:
  • Damage to bearings and crankshaft.
  • Pistons expanding and scraping against cylinder walls (crushing the head gasket).
  • Swelling, distortion, and breakage of cylinder heads.
• Solution: Regular maintenance, proper cooling system function, and avoiding excessive strain on the engine.

An overheated engine can lead to serious problems like blown head gaskets and cracked cylinder heads. For optimal performance, keep your engine’s operating temperature between 190-220 degrees Fahrenheit. Excessive heat puts undue stress on the cylinder head, liners, and engine block, causing them to expand beyond their designed limits. This expansion is the primary cause of head gasket failure and cylinder head damage.

Oil Leakages:

• Causes: Gaskets that no longer work effectively.
  • Aged seals and gaskets 
  • Damaged seals and gaskets
• Consequences:
  • Environmental threat.
    • An oil leak from any vehicle can cause contamination to local wildlife, water supplies for houses and farms using wells, livestock, and more.
  • Serious fire risk.
    • A more obvious and immediate risk is oil leaking on hot engine components like the exhaust manifold, which is the most common cause of engine fires.
  • Complete engine failure.
    • Simply put, engines without engine oil overheat and seize. When that happens an engine rebuild or a new engine is needed. This is the expensive one.
• Solution: Promptly address oil leaks to prevent further damage.

Oil Leaks: More Than Just a Mess!

Oil leaks on your driveway might seem like an inconvenience, but they can pose significant environmental and personal risks.

• Environmental Impact: 
  • Toxic contamination: Used motor oil contains harmful substances like lead, zinc, and arsenic, which can seep into water systems if washed away by rain or irrigation. This contamination harms plant and animal life in nearby waterways.
• Vehicle Damage:
  • Engine and Component Wear:
    • Leaking oil can damage your engine, radiator, and HVAC system. Accumulated oil degrades rubber components like hoses and seals, leading to premature wear and tear.
• Personal Safety:
  • Fire Hazard:
    • Leaking oil can ignite, causing serious fires.
  • Engine Failure:
    • A major oil leak can lead to engine seizure while driving, potentially causing accidents and injuries. Even mild cases can result in expensive repairs or complete engine replacement.
• Taking Action:
  • Addressing oil leaks promptly is crucial for protecting the environment, your car, and your safety. Consult a mechanic for a professional diagnosis and repair.

Part-Specific Problems:

• Shop All Pistons:
  • Failures include:
    • Worn-out piston rings.
    • Noisy pistons (piston slap).
    • Burnt pistons (due to dirty fuel injectors).
    • Cracked pistons (from poor-quality fuel).

What Causes Damage to Engine Piston Parts?

So that you can take action before any damage affects the engine, we’ve compiled a list of the most common and specific causes of piston damage to ensure you can easily recognize the problem. 

Common Causes of Diesel Piston Damage

Diesel engines are workhorses, but even the toughest engines can succumb to wear and tear. 

Here are some common causes of piston damage in diesel engines:

• Dirty Fuel Injectors
  • Clogged diesel fuel injectors can cause uneven fuel distribution, leading to localized overheating and burned pistons.
• Low-Quality Diesel Fuel: 
  • Using low-quality fuel can compromise lubrication and contribute to piston wear and cracks.
• Piston Ring Issues:
  • Worn Rings: Over time, diesel engine piston rings wear, compromising the seal between the piston and cylinder. This can lead to oil leaks, power loss, and white smoke from the exhaust.
• External Damage:
  • Air Filter Neglect: Failure to replace air filters allows dirt and debris to enter the engine, potentially damaging the piston skirt and causing wear or breakage.

Warning Signs

• Rattling or knocking noises: This could indicate excessive clearance between the piston and cylinder wall.
• White Smoke: This might point towards worn piston rings and oil burning.
• Power Loss: This could be a symptom of worn rings leaking compression.

Tips to Prevent Piston Damage:

• Use high-quality fuel and clean injectors regularly.
• Change oil and filter at recommended intervals.
• Maintain a clean air filter.
• Seek professional diagnosis and repair at the first sign of trouble.

Shop for Head Gaskets:

Cause of Failure: Overheating via coolant leaks.

Diesel Truck Head Gasket Problems

Head gaskets have been a source of issues for diesel trucks since the early days. As we said above, it’s not always technically the gasket’s fault. For any number of reasons, the seal between the engine block and the head is not performing as it should.

If you’re upgrading the power in your truck, upgrade to a performance head gasket rated for the cylinder pressure you have in mind. Otherwise, the cylinder head can lift and stretch the bolts. That leads to a loss of clamping force on the gasket. This can lead to the problems we discussed above, like loss of power, coolant leaks, weird smells, and exhaust smoke.

Diesel Engine Head Gasket Thickness

Head gasket thickness is an often overlooked factor to avoid leaks and failures. If you have the engine block decked or resurfaced to achieve a flat, smooth surface, you may need a thicker gasket to maintain the proper piston clearance. Using the wrong head gasket thickness could cause piston-to-valve contact, resulting in serious engine failure. You can have the engine decked multiple times and use slightly thicker gaskets for each round.

One of the most critical factors in head gasket performance is proper clamping force. This is governed by the type of head fasteners, the engine deck fastener holes and structure, and the installation. It’s critical to torque the diesel engine cylinder head fasteners to the correct torque and in the correct pattern as specified in the shop manual or other manufacturers’ instructions.

For example, the Ford 6.0L Power Stroke was notorious for head gasket failures. Many stock engines failed between 70,000 and 150,000 miles. Performance tuners got only 20,000 to 80,000 miles.

A Blown Head Gasket is the Issue?

The failure is commonly called a blown head gasket, but that’s not fair. The real problem was that the cylinder head bolts stretched, reducing the clamping force on the gasket. Yes, the gasket leaked, but it wouldn’t have with proper clamping force. The best fix is to install cylinder head studs while replacing the gasket and repairing any other damage to the engine.

The head fasteners in the 2005-2006 6.0L Power Stroke were the common torque-to-yield (TTY) bolts. The goal of using these bolts is to ensure the maximum clamping force. TTY bolts are torqued to a specified setting and then turned an additional quarter or half turn to reach the specified angle of the bolt head. The bolt threads were designed to clamp down a given amount in the final turn to ensure consistent pressure across the head. But things didn’t work out that way. Unfortunately, the bolts were not strong enough to go over 150,000 miles without stretching.

The blighted 6.0L also suffered from EGR Cooler failures. If the internal brazing cracked, pieces could get sucked into the intake manifold and blow the head gasket.

All Diesel Engines Need Maintenance, Eventually!

Each engine manufacturer has particular issues leading to diesel head gasket failure. Ram Cummins and GM Duramax diesel engines typically have six head bolts around each cylinder, which helps reduce gasket problems. The Duramax V8 engines were designed with 18 head bolts per cylinder bank. The Cummins inline sixes use 24 head bolts. Having more cylinder bolts helps spread the clamping force across the head and around each cylinder. In Ford’s case, the 6.0L and 6.4L Power Stroke engines had four head bolts per cylinder, which contributed to their problems.

Remember, regular maintenance, proper fuel, and vigilant monitoring can help prevent these common diesel engine problems. Keep your diesel engine healthy, and it will serve you well!