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​An Expert’s Guide to Diesel Engine Rebuilds

Oct 19th 2023

diesel engine during service

slaved / shutterstock

Diesel engines may last up to a million miles or more, but they might need a complete rebuild to reach that milestone. It’s an involved process that requires expert knowledge and access to a wide range of replacement parts and tools, but the results are more than worth it. Rebuilding the engine will extend your truck’s lifespan by 100,000 miles or more, preventing you from having to buy a new vehicle. It’s also a fun project that will teach you everything you need to know about how diesel engines work.

If you rebuild the engine before it breaks down, you can salvage some of the existing parts, reducing the overall cost. The process will make your old truck feel new, leaving you with increased fuel efficiency, more towing power and faster acceleration. Use this guide to prepare for your first diesel engine rebuild.

What Is an Engine Rebuild?

An engine rebuild means removing the engine, taking it apart, cleaning or replacing damaged parts, putting it back together again and reinstalling it in the vehicle. No two rebuilds are exactly alike. The process varies based on the make and model and overall condition of the engine. Builders restore vintage models and vehicles with signs of wear and tear. If your truck is consuming more fuel than usual, having trouble accelerating, losing power, emitting smoke out the hood or exhaust or hearing strange sounds from the hood, your truck may need a rebuild.

Diesel engines require more parts and are generally more involved than gas-powered engines. They burn highly compressed fuel at high RPMs by injecting it directly into the combustion chamber, use turbochargers to increase power, require more oil and treat the exhaust to prevent the spread of hazardous emissions, all of which must be maintained or replaced. For example, Powerstroke engines use exhaust gas recirculation (EGR) systems to recycle the exhaust.

Learn more: What Does an EGR Valve Do?

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Assembling Your Gear

A diesel engine is a tightly wound machine that only works when all the parts are in sync. You need gear to remove and reinstall the engine, including cleaning, timing, measuring and honing tools.

If parts of the engine are still usable, you must clean them before putting them back in the engine. If your truck has seen several hundred thousand miles of heavy towing or more, get ready to replace many of the components and systems. The coolant, oil and fuel systems usually need the most attention. The injectors will clog due to poor lubrication. Find replacement diesel fuel injectors to improve efficiency.

The engine needs a steady supply of high-quality oil to generate power. Take apart and clean the oil system to remove blockages. The high-pressure oil pump (HPOP) may also need to be replaced to improve timing and circulation. Shop for replacement HPOPs online for every make and model. Keep everything required to replace these parts on hand to avoid installing them incorrectly. You will need the following tools to rebuild a diesel engine:

  • Micrometers
  • Cam bearing installation kit
  • Spring height tool
  • Crankshaft socket
  • Valve spring compressor
  • Spring tester
  • Camshaft holder
  • Honing tool
  • Dial calipers
  • Valve seal installer
  • Torque wrench
  • Deck bridge tool
  • Dial indicator
  • Harmonic balancer puller
  • Valve spring tester
  • Work light or headlamp

Budgeting for a Diesel Engine Rebuild

The cost of the project ranges based on the condition of your engine, namely how many parts need to be replaced and how many tools you have. Shopping for parts online and refurbishing worn items will save you money. Expect to spend anywhere from $20,000 to $40,000 on the entire rebuild when doing everything yourself.

closeup car of car engine

iliart / shutterstock

Tips for a Successful Diesel Engine Rebuild

Keep these ideas in mind to get the job done like a pro:

  • Be Precise with Your Measurements

Follow the recommendations precisely and measure your parts beforehand to make sure they match your make and model.

  • Choose Your Model Wisely

Consider fixing up a truck with easily accessible parts instead of vintage models that have long been off the market. The latest models also have tutorials and guides online to help you through the process.

  • Keep a Clean Workspace

Water, grease and residue can ruin your parts and tools, gunking up the engine. Keep your supplies away from the danger zone.

  • Gather Your Parts Ahead of Time

Nothing will delay the rebuild like not having the right tool at the right time. Collect everything up front to focus on the task instead of waiting for a delivery.

Give your diesel engine a second life with a complete rebuild.

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