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Mack E7 Engine

Mack E7 Engines For Sale

The Mack E7 engine was first conceptualized in 1988 by Mack Corporation engineers and was then officially introduced in 1989. The Mack E7 replaced the Mack E6 model and would end up being in production for over 20 years. The engine was predominantly used in commercial, on-highway trucks. During its production, the engine was subject to various revisions until Mack finally ended its production at the beginning of the 21st century. The Mack E7 is one of the most popular industrial diesel engines of all time.

Both large scale and small-scale operations flocked to the Mack E7 for its well-documented reliability and fuel efficiency. By 1999, Mack had produced 16 different variations of the E7, and Mack E-Tech engines are still being produced today (and still retain a tremendous reputation for their advantageous horsepower-to-weight ratio). Mack E-Tech engines are six-cylinder, multi-system cooled, and the typical horsepower rating for the used Mack E7 engines we sell is between 250-400 hp.

Engine Applications and Uses

  • Mining
  • Oil & Gas
  • Agriculture
  • Construction
  • Industrial
  • Class 8 Heavy-Duty

Common Mack E7 Engine Problems & Failures

We tend to notice pattern problems in the used Mack E7 engines our customers are considering replacing. Because of that, we’ve compiled a list of common problems that are frequently reported. Some of the failures listed below may mean your engine has run out of time. However, if caught soon enough, some of these problems may leave the original engine salvageable.

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  • Spun Crankshaft Bearings
  • Cracked Cylinder Head
  • Scored Pistons and Liners
  • Overfueling
  • Lack Of Oil or Oil Pressure
  • Extreme Blow By
  • Dropped Valves
  • Camshaft Failure
  • Crankshaft Failure
  • Lifter/Roller Failure
  • Connecting Rod Failure

Mack E7 Engine Replacement Options

In some cases, your Mack E7 is beyond saving. In others, your engine may just need a few new parts, or maybe a simple refresh and reseal. We understand that time, money, and availability factor into your decision—and that’s exactly why we’ve provided both the pros and cons of sourcing a new engine from a dealer.

Mack E7 Mechanical Engines for Sale Replacement Options Chart

The Big Bear Engine Remanufacturing Process

For those that’ve suffered an unfortunate catastrophic engine failure, a remanufactured E7 long block is the perfect remedy. This option is ideal if you have good, reusable external components that are still functionable and can be salvaged from your original engine. Most importantly, this is a good choice if you’re trying to save some money.

We always uphold a professional level of service, whatever the task may be. In the sphere of engine remanufacturing, we ensure this level of quality is upheld by first executing a full core tear down, cleaning, inspection, and machining of the engine. This is carried out on every engine we build.

It is important to note that all of our E7 remanufactured long blocks are built with both reman and new parts. We do not recondition or refurbish old parts. Instead, we completely rebuild your old E7 engine back to its original OEM specs.

Thorough Cleaning

Thorough cleaning is imperative in the engine remanufacturing process. This is why we rid your engine of any impurities that could contribute or cause future component failure or engine failure. This is achieved by stripping the E7, then putting the block, head, rods, crankshaft, and camshafts through a chemical jet wash or hot tank.


Before our quality control department inspects the final product, the crankshaft is precision machined to precise tolerances, polished, and then magnafluxed.

Cylinder Head

Each E7 head is resurfaced to both guarantee a proper sealing surface with the block and a finish that’s compatible with today's new gasket materials. Valve height is mic’d and the head is also vacuum tested to ensure correct valve seating.


We employ magnafluxing to inspect the block for any cracks or other damage. Once the crankcase checks out, the cylinders are bored, honed and again inspected. Torque plate honing is performed on particular engines to eliminate the chances of cylinder distortion after the head is installed and torqued to the block. This process eliminates a primary cause of engine blow-by. Block surfaces are then machined and inspected to ensure proper finish.


The camshaft is inspected and precisely machined to provide correct lift. Lobes are then measured with a micrometer to make sure OEM tolerances are met.

Connecting Rods

In order to achieve even distribution of stress on the bearings, the connecting rods are cleaned, machined to OEM specs, and then honed to the standard diameter of the original equipment. New bushings are also fitted and machined in all bushed rods. Each rod is also inspected for signs of bend and/or twist.

New Parts

Good performance and reliability are what we strive for here at Big Bear Engine Company. Therefore, every Mack E7 engine receives all new pistons and rings, bearings, gaskets and seals, and liners. The new parts employed in the used Mack engines we sell consist of both OEM and aftermarket, when available.

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Remanufactured Engine Standards

To best define remanufacture, would be to make as close to new as possible. In pursuit of this, all wearable parts are automatically replaced. All E7 core material is thoroughly inspected and examined against original equipment specifications for correct dimensional tolerances, and replacement parts are either new or requalified. If new, parts are made in the same production processes as original equipment. Testing is performed to manufacturer specifications and original production standards.

Mack E7 Long Block Parts List:

  • Block
  • Complete Loaded Cylinder Head
  • Intermediate Cover
  • Timed Front Gear Group
  • New Upper and Lower Gasket Set
  • Camshaft
  • Followers/Lifters
  • Crankshaft
  • Connecting Rods
  • Pistons
  • Liners
  • Rings
  • **1 Year Warranty

*Note: We can provide a new oil pump, oil cooler, water pump, turbo, injectors and fuel pump for additional cost(s) with the long block, but these components will not come assembled to the engine.

**1-Year Warranty: First 6 Months Parts & Labor, Second 6 Months Parts Replacement Only. Ask your sales representative for a full copy of our remanufactured long block warranty.

MACK E7 Specs

Engine Data

Bore4.875-inches (123.83 mm)
Stroke6.500-inches (165.10 mm)
Displacement12.0L (728 ci)
Compression Ratio16.5:1 = up to 375 hp, above 375 hp = 15.3:1

Give us a call today at 844-340-4114 to view our Mack E7 engines we have for sale or for immediate sales and support for the Cummins 4BT, Cummins 6BT, 6CT, ISC, 855, QSB 4.5 L or CAT 3306. If you have any questions, check out our FAQ Page. We are always ready to help or just listen to your crazy off-roading adventures!

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