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Posted on April 25, 2025April 30, 2026 by David Ley

Why Cummins Injector System Upgrades Change Failure Patterns (Mechanical vs CELECT vs HPI vs XPI)

Cummins didn’t just evolve injector systems to improve performance – they fundamentally changed how engines fail, how they’re diagnosed, and how repairs need to be approached.

From mechanical injectors to XPI common rail systems, each generation introduced new advantages – but also new failure modes.

If you’re diagnosing fuel system issues on a Cummins engine, understanding these differences is critical.

Posted on April 20, 2025April 30, 2026 by David Ley

Volvo D13 / Mack MP8 Turbo Overspeed Failure: What Causes It And Why Replacing The Turbo Isn’t Enough

Turbocharger failure on a Volvo D13 or Mack MP8 engine isn’t always caused by wear – it’s often the result of turbo overspeed conditions driven by VGT control issues, exhaust imbalance, or air system faults.

In many cases, the turbo fails because it was forced to operate outside of its design limits – not because the turbo itself was defective.

Understanding what causes turbo overspeed is critical to preventing repeat failures.

Posted on April 20, 2025May 1, 2026 by David Ley

Cummins ISX Inframe Rebuild Failure: Why Your New Liners Aren’t Sealing (And How to Fix It)

You finished the inframe. New liners, pistons, rings – everything looks right.

But now you’re seeing:

Blow-By
Oil Consumption
Low Compression
Or Worse… It’s Smoking Under Load

This isn’t uncommon on Cummins ISX engines – and it usually comes down to one issue:

Improper liner protrusion and ring seating during install.

If you don’t get this right, your rebuild won’t last – no matter how good your parts are.

Posted on April 19, 2025April 30, 2026 by David Ley

DD15 Diesel Engine Pistons: How They Control Blow-By and What Causes Failure

Blow-by is not just a symptom.

It is a direct result of combustion pressure escaping past the piston assembly.

On a Detroit Diesel DD15, controlling blow-by comes down to one thing:

How well the piston, rings, and liner seal under load.

If that seal fails, everything else starts to follow.

Posted on April 13, 2025April 30, 2026 by David Ley

Cummins ISX Crankshaft Failure: Signs, Causes, and What to Do Before It Costs You an Engine

When a Cummins ISX starts running rough, vibrating, or misfiring, most people don’t immediately think about the crankshaft.

That’s the problem.

Because by the time the crankshaft shows obvious symptoms, the damage is usually already happening inside the engine – and it doesn’t take long before it turns into a full rebuild.

If you’re dealing with vibration, low oil pressure, or unusual engine noise, this is one issue you don’t want to ignore.

Posted on April 12, 2025April 30, 2026 by David Ley

Caterpillar 3406E, C15, C15 ACERT Spacer Plate: How It Controls Liner Height and Sealing

The spacer plate in a Caterpillar 3406E, C15, and C15 ACERT is not just a structural component.

It is a critical part of the engine’s sealing system.

It directly controls:

Cylinder Liner Protrusion
Head Gasket Clamping Force
Combustion Sealing Integrity

If the spacer plate is worn, damaged, or machined incorrectly, the entire sealing system is compromised.

Posted on April 4, 2025April 30, 2026 by David Ley

Cummins Diesel Engine Serial Numbers

Look at your rocker cover: you’ll probably find your Cummins ISB engine serial number. You might also find it on the side of the gear housing. If you have a Cummins ISM engine, the serial number is on the rocker housing on the fuel pump side.

Posted on April 1, 2025April 30, 2026 by David Ley

Diesel Cylinder Head and Engine Rebuild Kit Bundle Sale

Highway and Heavy Parts is excited to introduce our new diesel engine parts bundle sales promotion. It includes diesel cylinder heads and diesel engine add-ons for all major heavy-duty truck and equipment manufacturers. If you need a cylinder head for your Cummins, Caterpillar, Detroit Diesel, or other heavy-duty diesel engine, you can get everything you need to do the job right and save some money.

Posted on March 30, 2025April 30, 2026 by David Ley

How to Clean EGR Pressure Ports in Diesel Engines (Without Causing Damage)

EGR pressure ports are small, but they play a critical role in how a diesel engine manages emissions and airflow.

When they clog, it can lead to:

Fault codes
Engine derate
Poor performance
Misdiagnosed EGR system failures

Cleaning them correctly matters just as much as diagnosing the issue.

Posted on March 27, 2025April 30, 2026 by David Ley

Detroit Diesel Series 60 14L Turbocharger: Symptoms, Failure Causes, and When to Replace

The turbocharger on a Detroit Diesel Series 60 14L engine does more than add power.

It controls airflow, and airflow controls combustion.

When the turbo isn’t performing correctly, the entire engine starts to fall out of balance.

Posted on March 25, 2025April 30, 2026 by David Ley

Caterpillar C15 and 3406E Oil Pump: Symptoms, Failure Causes, and When to Replace

Low oil pressure isn’t something you ignore on a diesel engine.

On a Caterpillar C15 or 3406E, it’s often a warning sign that something deeper is going wrong inside the engine.

And in many cases, the issue starts with the oil pump.

Posted on March 8, 2025April 30, 2026 by David Ley

What Happens When a Diesel Engine Sits Too Long? (Fuel, DEF, and Internal Damage Explained)

Diesel engines are built to run – not sit.

At Highway and Heavy Parts, we regularly work with engines that come out of storage with unexpected performance issues. In many cases, the root cause isn’t a failed part: it’s what happened while the engine wasn’t running.

Whether it’s a backup truck, seasonal equipment, or a unit waiting on work, extended downtime can quietly create problems that don’t show up until the engine is put back into service.

And in many cases, those problems get misdiagnosed.

From fuel degradation to DEF crystallization and internal wear, here’s exactly what happens when a diesel engine sits too long – and what to look for before putting it back to work.