When an excavator or loader goes down on a job, the meter starts running on everything else. The crew is waiting, the hire company is still charging and the client wants to know when you’ll be back. If you’re looking for a Cummins QSB engine for sale, you’re probably in that position, or you’re a workshop trying to get a customer’s machine, generator or boat going again as fast as possible.
We’re NJ Global Auto Parts. We supply used and rebuilt engines to contractors, workshops, marine operators and equipment dealers all over the world. The Cummins QSB family is one of the most common engines in mid size equipment, and we deal with it often. This guide covers the versions, specifications, where they’re used, the problems we see, the checks we make on every Cummins QSB engine for sale, pricing and shipping. It’s the same thing we’d tell you if you rang us from site.
Table of Contents
What You Get With a Cummins QSB Engine for Sale
QSB is Cummins’ name for the off-highway version of its B Series diesel. The same basic engine family goes into trucks and buses under the ISB name. The QSB is built for machines, power generation and boats, with electronic control, ratings to suit each job and the mounting and cooling options that equipment builders need.
It comes in four and six cylinder versions. The main ones you’ll see are the QSB4.5, the QSB5.9 and the QSB6.7. They all share the B Series traits: cast iron block and head, four valves per cylinder, gear driven timing, turbocharging and a reputation for running a very long time when they get clean fuel, clean air and clean oil.
That’s why a Cummins QSB engine for sale is so useful. Parts are easy to get almost everywhere, most diesel mechanics know the engine, and a lot of different machines use it. For the family history, the Cummins B Series engine page is a good overview, and Cummins has official information on current engines and dealer support.
Cummins QSB Engine for Sale: Full Specifications
Ratings on the QSB vary a lot depending on what the engine is fitted to. A generator engine, an excavator engine and a marine engine can all be QSB6.7s with quite different power figures. The table below gives the typical ranges. Your engine’s data plate has the exact figures, and every Cummins QSB engine for sale we quote is matched to that plate.
| Model | QSB4.5 | QSB5.9 | QSB6.7 |
| Cylinders | Inline 4 | Inline 6 | Inline 6 |
| Displacement | 4.5 L | 5.9 L | 6.7 L |
| Bore x stroke | 107 x 124 mm | 102 x 120 mm | 107 x 124 mm |
| Aspiration | Turbocharged, charge air cooled | Turbocharged, charge air cooled | Turbocharged, charge air cooled |
| Fuel system | High pressure common rail | Electronic pump on earlier engines, common rail on later ones | High pressure common rail |
| Valves | 4 per cylinder | 4 per cylinder | 4 per cylinder |
| Typical industrial power | About 60 to 130 kW (80 to 173 hp) | About 97 to 205 kW (130 to 275 hp) | About 97 to 224 kW (130 to 300 hp) |
| Marine ratings | Not common | Up to about 280 kW in some ratings | Up to about 410 kW in some ratings |
| Block and head | Cast iron | Cast iron | Cast iron |
| Control | Electronic (ECM) | Electronic (ECM) | Electronic (ECM) |
Later engines built for stricter emissions rules (such as Tier 4 and Stage IV/V) may also have exhaust aftertreatment like a diesel particulate filter or SCR system, plus different electronics. Keep that in mind, because it affects what parts come with the engine and what your machine expects.
Where the QSB Is Used
You’ll find the QSB in a huge range of equipment. Some of the most common uses are:
- Excavators in the 13 to 25 tonne range, including many Hyundai models
- Wheel loaders, backhoe loaders and skid steers
- Telehandlers, forklifts and container handlers
- Mobile cranes and aerial work platforms
- Tractors, sprayers and harvesters
- Generator sets and standby power
- Compressors, pumps and mining support equipment
- Commercial and pleasure boats, from work boats to cruisers
Because the same engine is built in so many configurations, the details change a lot between machines. Sump shape, flywheel housing, front cover, fan drive, wiring and ECM calibration can all differ. That’s why we always ask for your engine serial number (ESN) and CPL number from the data plate before we confirm a Cummins QSB engine for sale will fit.
Why the ESN and CPL Matter
Every Cummins engine has an ESN, the engine serial number, and a CPL, the control parts list. The CPL tells you how the engine was built: which parts, which fuel system, which rating. Two QSB6.7s with different CPL numbers can need different parts to fit the same machine.
If you send us a clear photo of your data plate, we can match a Cummins QSB engine for sale to your build, or tell you exactly what needs to change to make it fit. This one step saves more money and time than anything else in the buying process.
Used, Rebuilt or Long Block?
Here’s what the main options mean when you look at a Cummins QSB engine for sale.
Used complete engine. Taken out of a donor machine or generator with the turbo, fuel system and most parts attached. It’s the fastest and cheapest fix if the hours are reasonable and it tests well.
Long block. Block, head, crank, pistons and timing gears, without most of the bolt-on parts. You transfer your own fuel system, turbo and accessories. A good option when the rest of your engine’s parts are healthy.
Rebuilt engine. Stripped and rebuilt with new pistons or rings, bearings, gaskets and seals, and a reconditioned head. It costs more, but for a machine that works long hours it usually pays for itself.
Our articles on used diesel engines and rebuilt vs used engines go into more detail.
7 Checks We Make on Every Cummins QSB Engine for Sale
These are the checks we run before we’ll put our name on a Cummins QSB engine for sale.
1. ESN, CPL and Donor Details
We record the engine serial number and CPL, and note the donor machine, hours and application where known. This tells us exactly how the engine was built and what it will fit.
2. Compression on Every Cylinder
We test compression on all four or six cylinders and look for even readings. A weak cylinder can point to ring wear, a valve problem or a head gasket issue.
3. Blow-By and Oil Condition
We check blow-by from the breather and look at the oil for signs of fuel dilution, coolant or metal. Heavy blow-by on a diesel is a sure sign of worn rings and liners, and dust ingestion shows up here first.
4. Fuel System
We check the injectors, the high pressure pump and the rail on common rail engines for leaks and signs of contamination. On earlier pump engines we check the pump. Fuel system parts are expensive, so we tell you exactly what condition they’re in.
5. Turbo
We check for shaft play, oil leaks and wheel damage. A turbo that’s been eating dirt will have a worn compressor wheel, and that’s a clue about how the engine was treated.
6. Cooling and Head
We look for signs of overheating, coolant loss and cracking. On marine engines we also check the heat exchanger, aftercooler and raw water side for corrosion.
7. What’s Included
We list everything on the engine: turbo, fuel system, ECM, wiring, starter, alternator, fan drive, sump and so on. That list comes with every Cummins QSB engine for sale we quote.
Common QSB Problems You Should Know About
The QSB is tough, but machines work in hard conditions and engines wear out. These are the usual problems we see.
Dust ingestion. A split intake hose or a badly fitted air filter on a machine working in dust will wear the rings and liners quickly. It’s the most common reason a QSB dies early.
Fuel contamination. Water and dirt in the fuel destroy common rail injectors and pumps. Symptoms include hard starting, knocking, smoke and low power.
Overheating. Blocked radiators on machines working in dusty or leafy environments are very common. Overheating leads to head gasket failure and cracked heads.
Turbo wear. Dirty oil and hot shutdowns wear turbo bearings. Black smoke and poor power follow.
Aftertreatment problems. On newer engines with a DPF or SCR, blocked filters and faulty sensors cause derates. These are often fixable without touching the engine itself.
Marine corrosion. On boat engines, neglected heat exchangers, raw water pumps and aftercoolers can let seawater into places it shouldn’t be.
Does Your Machine Really Need a New Engine?
Before you buy a Cummins QSB engine for sale, make sure the engine itself is the problem. A lot of QSB faults are fuel, air or electronic.
Low power and derates can be a sensor, an aftertreatment fault or a blocked air filter. Smoke can be injectors or a turbo. Coolant loss can be a hose, a radiator or an oil cooler. A compression test, a blow-by check and an oil analysis will tell you whether the engine is really worn out.
If it is, replacing the engine is almost always much cheaper than replacing the machine. A sound excavator or loader with a good Cummins QSB engine for sale fitted can go on working for years.
How to Tell a Good Cummins QSB Engine for Sale From a Bad One
Ask for the data plate. ESN and CPL should match or suit your build. A seller who doesn’t know the CPL of the Cummins QSB engine for sale they’re offering is not a seller who checked it properly.
Ask for a running video. Cold start, idle, and a rev if possible. Look for quick starting, a steady idle and little smoke once warm.
Check the breather. A light wisp is fine. Heavy smoke pumping out means worn rings.
Look at the turbo inlet. A clean compressor wheel with sharp blades is good. A dull, sandblasted wheel means the engine has been breathing dirt.
Ask about hours and use. A generator engine with low hours and a machine engine with the same hours have lived very different lives.
Compare prices. If one Cummins QSB engine for sale is much cheaper than the rest, ask why before you pay.
What Affects the Price of a Cummins QSB Engine for Sale
- Model. A QSB6.7 costs more than a QSB4.5, and marine versions carry their own pricing.
- Used or rebuilt. Rebuilt engines cost more but come with new internal wear parts.
- Emissions level. Engines with aftertreatment and newer electronics are priced differently.
- How complete it is. Fuel system, turbo and ECM add a lot of value.
- Hours and condition. Lower hours and good test results are worth paying for.
- Freight. Where you are and how quickly you need it changes the delivered price.
We quote the engine, what’s included and freight together. You can see what’s available on the Cummins QSB engine product page and in our Cummins engines range.
Shipping a Cummins QSB Engine for Sale Worldwide
We ship to contractors, workshops and boat owners across Africa, the Middle East, Asia, the Pacific, Europe and the Americas. Every engine is drained, sealed, strapped to a strong pallet or crated, and wrapped. Openings are capped so dirt and water stay out.
Sea freight is the usual choice for an engine this heavy. Air freight is possible and sometimes worth it for a machine on a contract with penalties for delays. We’ll price both if you want.
Each Cummins QSB engine for sale ships with a commercial invoice and packing list. Duties and taxes depend on your country. Check with a customs broker before it lands. The World Customs Organization has general guidance. Our shipping policy and billing terms explain our side.
What Happens When the Engine Arrives
Engines often arrive at a yard or a site rather than a tidy workshop, so this is worth getting right. Before you sign for the delivery, look over the crate or pallet. If it’s broken, wet or the straps have shifted, take photos with the driver present and write it on the delivery note. That protects you if anything was damaged on the road.
Once it’s unpacked, check the ESN on the data plate matches the one on your quote, and go through the list of included parts. Look closely at the injector lines, sensors, wiring connectors and the turbo, since those are the parts most likely to get knocked. If anything isn’t right, send us photos straight away. We keep our own inspection photos for every Cummins QSB engine for sale that leaves us, so we can compare and fix the problem quickly.
Keep it covered and out of the rain until it goes in, and leave the caps on the openings until the last minute. Dust getting into an open intake on a building site is exactly how engines get ruined before they’ve even run.
Buying for a Hire Company or Fleet
Hire companies and contractors with several machines on the same engine are some of our regular customers. The smart ones keep a spare engine ready to go, so a failure costs them a day or two of downtime instead of weeks waiting for parts.
If you run more than a couple of QSB powered machines, we can hold stock for you, ship several engines together to bring freight costs down, and keep test records for each Cummins QSB engine for sale we supply. That record is handy when you sell the machine later, because the buyer can see what went into it. Tell us how many machines you run and which models, and we’ll put a proposal together that makes sense for your fleet.
Fitting Tips From Equipment Mechanics
Fitting a Cummins QSB engine for sale is routine work for a heavy equipment mechanic. These steps help it last:
- Clean the radiator, charge air cooler and oil cooler properly. Blow them out from both sides.
- Check every intake hose and clamp between the air filter and the turbo. One split hose can ruin an engine.
- Fit new fuel filters and drain the water separator. Clean the tank if there’s any sign of water or sludge.
- Fresh oil and filter, and prime the lube system before first start.
- Make sure the ECM calibration suits the machine. Your dealer or a Cummins tool can check this.
- Bleed the fuel system and check for leaks at every fitting.
- Run it to temperature, check for leaks and codes, then put it to work gradually.
Looking After the QSB Once It’s Working
- Change oil and filters on time, and more often in dusty or heavy work.
- Check and change air filters regularly. Use good quality filters.
- Drain the water separator daily on machines in humid or wet conditions.
- Blow out the cooling pack regularly.
- Let the engine idle for a few minutes before shutting down after heavy work.
- Take an oil sample now and then. It warns you of problems long before a breakdown.
A Note on Marine QSB Engines
Marine QSB5.9 and QSB6.7 engines are built differently from their land based cousins. They have heat exchangers, raw water pumps, wet exhausts and marine rated turbos and manifolds, and many have higher power ratings. If you need a Cummins QSB engine for sale for a boat, tell us the vessel, the gearbox and the current rating. A marine engine that’s been looked after is a great buy. One that’s been sitting with seawater in it is not. We check marine engines for corrosion with extra care. If you work on boats, our guides on the Caterpillar C18 marine engine and Yanmar 8LV marine engine may also help.
Questions to Ask Before You Pay for a Cummins QSB Engine for Sale
- What are the ESN and CPL, and do they suit my machine?
- What were the compression readings?
- How many hours, and what did it come out of?
- Can I see a running video?
- Does it include the fuel system, turbo and ECM?
- What warranty comes with it?
- How will it be packed and what will freight cost to my site?
Other Diesel Engines We Supply
If you came for a Cummins QSB engine for sale but run other equipment or trucks too, we also supply:
- Cummins ISB, the on-road version of the B Series
- Caterpillar 3306 for older machines and gensets
- Mitsubishi 4M51 for Fuso Fighter trucks
- Isuzu 4JB1 for small equipment and light trucks
- Caterpillar engines for heavy equipment
The full range is in our used engines section.
Why Buy From NJ Global Auto Parts
In equipment, the wrong engine costs more than money. It costs days on site. We try to get it right the first time by matching engines to your data plate, testing them and describing them honestly. If we don’t think an engine suits your machine, we’ll tell you.
Read more about us, our refund and returns policy, or visit the shop. The blog has more guides.
Frequently Asked Questions
What’s the difference between QSB and ISB?
They’re the same basic B Series engine. ISB is built for trucks and buses, QSB for equipment, generators and boats. Parts and electronics differ.
Can I replace a QSB5.9 with a QSB6.7?
Sometimes, but it usually means changes to mounts, wiring, ECM and cooling. It’s normally easier to stay with the same model.
What do ESN and CPL mean?
ESN is the engine serial number. CPL is the control parts list, which describes how the engine was built. Both are on the data plate.
Is your Cummins QSB engine for sale used or rebuilt?
We offer both. Every quote says which.
Does it come with a warranty?
Yes. Terms depend on used or rebuilt and are written on your quote.
Do you ship to my country?
Very likely. We ship worldwide, mostly by sea, and quote freight before you pay.
A Cummins QSB engine for sale is only a good buy if it matches your build and has been tested properly. That’s how we work. Send us a photo of your data plate through the contact page, tell us what machine it’s for and where it is, and we’ll come back with what we have and a delivered price.