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Cat 3126 Engine

CAT 3126 Engines For Sale

The 3126 Cat is a turbocharged 7.2L inline 6-cylinder diesel engine produced by Caterpillar and first introduced in 1997; it was the very first electronic mid-range diesel engine that Cat had produced. The Caterpillar 3126 was the successor of the 3116. Both the 3116 and 3126 earned a fairly poor reputation due to cracked blocks and dropped valves. However, the source was reportedly traced back to a French foundry that was producing poor castings.  Despite the rumors, that was in fact only the 3116, of which Cat proactively recalled the blocks.

Further criticism of the 3126 Caterpillar Engine scarred its reputation as many marine users were complaining of faults. It was found that some marine users were using the higher powered 3116 and 3126 in their boats and running them at over 100% power in order to get their boat up on a plane. Yet, to do this, the user had to run these engines at 2800+ RPM despite the redline on the 3126 being around 2200rpm. This meant a lot of these engines had to be replaced, subsequently damaging the reputation of both engines. However, if these engines are treated accordingly, they are in fact a very reliable.

Engine Applications and Uses

  • Construction
  • Agricultural
  • Marine
  • Buses
  • Ambulances

Common CAT 3126 Engine Problems & Failures

We noticed some recurring themes from clients who were intending to replace their 3126 Caterpillar engines. So, we have gathered a list of recurrent problems that are often reported. Some of the issues featured below may mean your Caterpillar 3126 has run out of time, nonetheless, some may also be salvageable if caught in good time.

AERA Association Member

  • Spun Crankshaft Bearings
  • Cracked Cylinder Head(s)
  • Scored Pistons and Liners
  • Over Fueling
  • Lack of oil or oil pressure
  • Extreme Blow By
  • Dropped Valves
  • Camshaft Failure
  • Crankshaft Failure
  • Lifter/Roller Failure

Caterpillar 3126 Engine Replacement Options

Sometimes the truth is your engine is beyond saving, there are numerous causes than can impair your engine, but not all mean your engine is doomed. At times, your Caterpillar 3126 may just need a few new parts, or maybe it just needs a little refreshment to keep it in good shape. We do in fact appreciate that considerations such as time, money, availability, etc. will impact your decision making. Therefore, we have provided some insight by presenting both pro’s and con’s of a new engine from a dealer.

Remanufacturing Process

For those of you reading this that are luckless enough to have seen your engine suffer a dreadful failure, a remanufactured 3126 Cat long block would be the ideal answer. Moreover, if you have good re-usable external components that are still in good nick, then these can be salvaged from your much-loved 3126 Caterpillar engine. Most importantly, this would be a good substitute if your trying to work to a budget.

We constantly strive to uphold a professional level of service, whatever the task. In the realm of remanufacturing, we guarantee this level of quality is sustained by first executing a full core tear down, cleaning, inspection, and machining of the engine. This is carried out on every engine before it leaves our facility.

It is crucial to note, that all of our Caterpillar 3126 remanufactured long blocks are constructed with both reman and new parts. Therefore, we do not just recondition or refurbish old parts, instead we fully rebuild the old 3126 Cat engines back to original OEM specs.

Thorough Cleaning

Careful cleaning is essential during the process; therefore, we strive to relieve your engine of any contaminations that could promote or cause both component failure and/or engine failure. This is done by first stripping the 3126 Caterpillar Engine, then putting the blocks, heads, rods, crankshafts, and camshafts through a chemical jet wash or hot tank.


Before our quality control division inspect the finished product, the Caterpillar 3126 crankshafts are precision machined to the precise tolerances, polished and magnafluxed.

Cylinder Heads

3126 Cat heads are resurfaced to guarantee a proper sealing surface with the block and a finish compatible with today's new gasket materials. Valve height is mic-d and every head vacuum tested to assure correct valve seating.

Cylinder Blocks

The magnetic particle is used to inspect the 3126 Cat block for any cracks or further damage. The cylinders and then bored, honed and again inspected to the specific tolerances. Torque plate honing is performed on particular 3126 Caterpillar engines to eradicate the chances of cylinder head distortion when the head is bolted and torqued to the block. This process consequently removes the main source of engine blow-by. Block surfaces are then machined and inspected to ensure proper finish.


Caterpillar 3126 camshafts are inspected and precisely machined to provide correct lift. Lobs are measured with a micrometer to make sure OEM tolerances are met.

Connecting Rods

In order to attain an even distribution of stress on the bearings, the connecting rods are cleansed, then machined to the OEM specs, then, honed to the traditional diameter of the original equipment. New bushings are also fitted and machined in all bushed rods, every rod is also inspected for any bend and/or twist.


Great performance and reliability are what we strive for, therefore, all 3126 Caterpillar engines will obtain a set of new parts, namely pistons and rings, bearings, gaskets and sealers, and liners. These parts are both OEM and Aftermarket when accessible.

Request a Quote

Please fill out the form below with your information and request. A member of our staff will be with you shortly.

Remanufactured Engines Standards

To best define remanufacture, would be to aim to make as close to new as possible. In pursuit of this, all wearable parts are routinely replaced. All Caterpillar 3126 core materials are then carefully inspected and examined against the original equipment specifications for correct dimensional tolerances. Replacement parts are new or requalified. If new, parts are made in the same production processes as original equipment. Testing is also performed to manufacturer specifications and original production standards.

CAT 3126 Long Block Parts List:

  • CAT 3126 EngineCylinder Block
  • Complete Loaded Cylinder Head
  • Intermediate Cover
  • Timed Front Gear Group
  • Pistons
  • New Upper and Lower Gasket Set
  • Camshaft
  • Followers/Lifters
  • Liners
  • Rings
  • Crankshaft
  • Connecting Rods
  • **1 Year Warranty

*Note: We can provide new oil pumps, oil coolers, water pumps, turbos, injectors and fuel pumps for additional cost with the long block but will not come assembled to the engine.

**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.

CAT 3126 Spec

Engine Data 

Bore110mm (4.33 in)
Stroke127mm (5.0 in)
Displacement7.2L (442 cu in)
Flywheel RotationCounter-Clockwise
Capacity for Liquids28L (7.4 gal)
Lube Oil System (refill)25L (6.6 gal)
Oil Change Interval250 hrs
Engine Weight, Net Dry (approx)722 kg (1,592 lb)

Give us a call today at 844-340-4114 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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