If you’re hunting for a Caterpillar 3306 Engine for sale, there’s a good chance a machine is sitting idle somewhere and costing you money. A loader that won’t start, a dozer with a knock, a generator that’s lost power or an old truck that finally gave up. The 3306 has been doing that kind of hard, dirty work for decades, and people keep coming back to it because it’s one of the toughest diesels Caterpillar ever built.
That toughness is also why used 3306 engines vary so much. Some have been looked after and have plenty of life left. Others have spent years in dust and heat with the oil changed whenever someone remembered. From the outside, painted yellow on a pallet, they can look exactly the same.
We’re NJ Global Auto Parts, and we sell and ship engines like this to buyers around the world. This guide is what we’d tell you on the phone: the versions, the specifications, the machines it fits, the checks we make on every Caterpillar 3306 Engine for sale, the common problems, prices, shipping and fitting.
What a Caterpillar 3306 Engine for Sale Really Is
The 3306 is a 10.5 litre inline six-cylinder diesel from Caterpillar. It was introduced in the 1970s and built for a very long time, going into on-highway trucks, earthmoving machines, generator sets, marine applications, pumps and compressors. It’s a mechanical engine at heart, with Caterpillar’s own injection pump and governor, and that’s a big part of why people still want it.
There isn’t just one 3306. Early engines used precombustion chamber (PC) injection. Later ones moved to direct injection (DI), and the 3306B brought further updates. On top of that, the engine came naturally aspirated, turbocharged, or turbocharged and aftercooled. You’ll see names like 3306 DI, 3306 DIT and 3306 DITA, where T means turbo and A means aftercooled.
Caterpillar also gives each engine an arrangement number and a serial number prefix. Those tell a Cat dealer or a good mechanic exactly how that engine was configured: its rating, its pump settings, its sump, its flywheel housing and more. When you look at a Caterpillar 3306 Engine for sale, those numbers are worth more than any description.
If you’re curious about the company behind it, the Caterpillar Inc. page is a good read.
Caterpillar 3306 Engine for Sale: Full Specifications
These are the figures buyers ask about most. Power depends heavily on the rating and application.
| Engine model | Caterpillar 3306 (PC, DI, 3306B) |
| Layout | Inline six-cylinder, four-stroke diesel |
| Displacement | 10.5 L (638 cu in) |
| Bore x stroke | 121 mm x 152 mm (4.75 in x 6.0 in) |
| Combustion | Precombustion chamber on early engines, direct injection on later engines |
| Aspiration | Naturally aspirated, turbocharged (T) or turbocharged and aftercooled (TA) |
| Fuel system | Mechanical Caterpillar injection pump with mechanical governor |
| Power | Roughly 150 to 350 hp depending on rating and application |
| Rated speed | Typically around 1,800 to 2,200 rpm, depending on application |
| Dry weight | Around 1,000 kg, varying with configuration |
| Fuel | Diesel |
| Identification | Arrangement number and serial number prefix on the engine plate |
A generator set engine running at a fixed speed, a truck engine and a loader engine can all be 3306s and still have very different ratings, pump settings and parts bolted on. When we quote a Caterpillar 3306 Engine for sale, we give you the arrangement number, the serial prefix and the application it came from. With those, your mechanic can confirm it’s right.
Machines and Vehicles That Use the 3306
The 3306 went into an enormous range of equipment. The most common we get asked about:
- Track-type tractors such as the Cat D6 family. The Caterpillar D6 page gives a feel for the machines involved.
- Wheel loaders including 950 and 966 models of that era.
- Motor graders, excavators and other earthmoving machines.
- On-highway trucks from several American manufacturers in the 1980s and 1990s.
- Generator sets. The 3306 was a very common standby and prime power engine. See the diesel generator page for how these sets work.
- Marine propulsion and auxiliary engines, pumps, compressors and industrial power units.
Because the uses are so varied, the external parts vary too: sumps, flywheel housings, front drives, cooling and mounting. A Caterpillar 3306 Engine for sale from a generator may need parts changed to fit a loader. Send us your machine model and serial number, or the details from your old engine plate, and we’ll match it.
PC or DI, Turbo or Not: Which One Do You Need?
The simplest rule is to buy what the machine was built with.
If your machine had a precombustion chamber engine, a like-for-like PC engine is the least hassle. Some owners upgrade to a DI engine for better fuel economy and easier starting. It can be done, but the pump, injectors, and sometimes the lines and settings differ. Plan for it.
If your machine has a turbocharged and aftercooled engine, don’t drop in a naturally aspirated one to save money. You’ll lose a lot of power, and the machine won’t work the way it should. The reverse is also true: putting a high-rated TA engine into a machine designed for a lower rating can stress the transmission and cooling system.
The arrangement number solves most of this. Send it to us and we’ll find a Caterpillar 3306 Engine for sale that matches, or tell you what needs to change.
3306 vs 3406 vs C9: Don’t Mix Them Up
The 3406 is Caterpillar’s bigger inline six, around 14.6 litres, used in heavier trucks and machines. It’s a different engine with different mounts and a lot more weight. The C9 and similar later engines replaced the 3306 in many machines, with electronic controls and different fittings.
They’re all Cat sixes, they’re all yellow, and we’ve seen them confused in online listings. When you look at any Caterpillar 3306 Engine for sale, check the model on the plate, the arrangement number and the serial prefix.
Buying a 3306 for a Generator Set
A lot of the 3306 engines we sell go into generator sets, so it’s worth a few words of its own. A genset engine runs at a fixed speed, usually 1,500 rpm for 50 Hz power or 1,800 rpm for 60 Hz, and its governor and rating are set for that job. A Caterpillar 3306 Engine for sale taken out of a truck or loader will have different settings and often a different governor.
That doesn’t mean you can’t use it, but your electrician and mechanic need to know. The governor, pump settings, flywheel and flywheel housing all have to suit your alternator and your frequency. If you tell us the kVA rating and the frequency of your set, we’ll look for a Caterpillar 3306 Engine for sale from a matching generator application first, which makes the job far simpler.
Standby generators also have their own quirk: they often sit for long periods and then run hard. Engines from standby sets can have low hours but still need attention to seals, hoses and the fuel system. We check that too.
Fitting a 3306 Into a Different Machine
Some customers want to put a 3306 into a machine that originally had another engine, often because the 3306 is easier to support where they work. It’s a common kind of project, but it needs planning. You’ll have to think about mounts, the flywheel housing size, the driveline connection, cooling capacity, exhaust routing and the throttle linkage.
If that’s your plan, tell us the machine and what it had before. We’ll tell you what comes with the Caterpillar 3306 Engine for sale we’re offering and what you’ll need to make or source.
7 Checks We Make on Every Caterpillar 3306 Engine for Sale
These are the seven areas we look at before we quote, and the ones you should ask any seller about.
1. Engine Plate, Arrangement Number and Serial Prefix
We photograph the engine information plate and record the arrangement number, serial prefix and donor machine. That tells your mechanic exactly what the engine is. A Caterpillar 3306 Engine for sale without a readable plate isn’t necessarily bad, but it’s harder to match, and the price should reflect that.
2. Compression and Blow-By
We test compression on all six cylinders of every Caterpillar 3306 Engine for sale and, where the engine can be run, check blow-by from the crankcase. Heavy blow-by means worn rings or cylinder walls, higher oil use and lost power. Even readings and low blow-by are what you want.
3. Oil Pressure and Bottom End
Where we can run the engine, we check oil pressure hot and cold and listen for bottom-end knocks. Low oil pressure on a hot engine points to worn bearings. We look at the oil and filter for metal. Any of that and the engine goes for a rebuild, not onto our list as a good runner.
4. Fuel Injection Pump and Injectors
The Cat mechanical pump is strong, but it can be worn, leaking or adjusted beyond its rating. We look for leaks and signs of tampering, and check injectors where we can. On any Caterpillar 3306 Engine for sale, ask whether the pump has been turned up. It’s common, and it shortens engine life.
5. Turbo and Aftercooler (T and TA Versions)
On turbo versions of the Caterpillar 3306 Engine for sale we check turbo shaft play, oil in the intake, and the aftercooler for leaks. A leaking aftercooler can let coolant into the intake, which is bad news for an engine.
6. Cooling System, Head and Oil Cooler
We look for overheating signs, head gasket leaks, coolant in the oil and oil in the coolant. The oil cooler is a known place for the two to mix. Machines working in heat and dust overheat more than people think.
7. What’s Included
Pump, injectors, turbo, aftercooler, starter, alternator, flywheel, flywheel housing, sump and front drive all make a big difference to value and to fitting. We list everything that’s on the engine and show it in photos.
Common 3306 Problems You Should Know About
The 3306 is famous for lasting, but high hours and hard use leave marks. Knowing the usual faults helps you judge any Caterpillar 3306 Engine for sale.
Worn rings and cylinders. Dust and high hours raise blow-by and oil use.
Overheating. Blocked radiators on dusty sites, worn water pumps and slipping fan belts lead to head gasket failure and cracked heads.
Oil cooler failures. Coolant and oil mixing, which damages bearings quickly if ignored.
Worn bearings. Low oil pressure when hot, usually from age, dirty oil or overheating.
Injection pump wear or tampering. Smoke, poor power and hot running.
Injector nozzles. Worn nozzles cause smoke and rough running.
Rear main seal leaks. Common with age.
Our older guides on used Caterpillar 3306 diesel engines and rebuilt Caterpillar 3306 engines go into more detail.
Does Your Machine Really Need a New Engine?
Before spending big money, make sure the engine is actually finished. Smoke, hard starting and low power can come from injectors, the pump, a worn turbo or a blocked air filter. These signs usually do mean a replacement:
- Low compression on several cylinders.
- Heavy blow-by and high oil use.
- Low oil pressure when hot, or a bottom-end knock.
- Coolant in the oil that isn’t just an oil cooler problem.
- A cracked block or head.
A good heavy-equipment mechanic can tell you which side you’re on. If it’s done, a Caterpillar 3306 Engine for sale is usually the fastest way to get the machine earning again.
Rebuild Your Old Engine or Buy a Replacement?
Both can be right. A rebuild makes sense if the block and crank are good, you have a trusted workshop and the machine can sit for a while. A replacement makes sense if the block or head is cracked, the crank is damaged, or every day of downtime costs more than the price difference.
Many owners buy a Caterpillar 3306 Engine for sale to get working now and rebuild the old engine later as a spare. If you’re unsure, tell us what’s wrong and we’ll give you an honest view. Sometimes the right answer is a set of injectors and a turbo, not an engine.
Used, Rebuilt or Long Block?
Used. A tested engine from a donor machine, sold as described. For most owners who need a machine working quickly, a used Caterpillar 3306 Engine for sale is the sensible choice.
Rebuilt. Stripped, measured and reassembled with new wear parts where needed. More money, but a fresh start for machines with long working lives ahead.
Long block. The core engine without all the ancillaries. Useful if your pump, turbo and accessories are healthy.
See what’s available on our Caterpillar 3306 engine product page, or read our earlier guide to buying a Caterpillar 3306 online.
What Affects the Price of a Caterpillar 3306 Engine for Sale
- Version and rating. DI and TA engines usually cost more than older PC and naturally aspirated ones.
- Hours and condition. Even compression, good oil pressure and low blow-by add value.
- Completeness. The pump, turbo and aftercooler are worth real money.
- Used or rebuilt. A rebuild includes parts and a lot of labour.
- Freight. A 3306 is heavy. We quote shipping up front.
If a Caterpillar 3306 Engine for sale is priced far below everyone else, ask why. There’s usually a reason.
Hours, Not Kilometres
One thing that confuses new buyers: equipment engines are measured in hours, not distance. A loader engine with 10,000 hours has done a lot of work, but a 3306 that’s been serviced properly can go well beyond that before it needs a major overhaul. Hours alone don’t tell you much. How those hours were spent tells you more.
An engine that idled for half its life on a generator has worn differently from one that pushed dirt all day in the heat. That’s why we care more about compression, blow-by and oil pressure than about the hour meter. When we describe a Caterpillar 3306 Engine for sale, we give you the hours if we know them, but we lean on the test results to tell you how healthy it really is.
Buying for a Fleet or Rental Yard
If you run several machines or gensets on the 3306, consider keeping a spare engine ready. Downtime on a rental machine or a standby generator costs far more than the engine sitting on a shelf. Shipping two engines together also usually costs less per engine. Tell us your arrangement numbers and we’ll see what we can supply.
Buying From Overseas Without the Worry
Many of our customers are contractors, rental companies and workshops on other continents. Ask for photos of the actual engine, the plate, the test results in writing and a confirmed freight quote with the delivery point. We include all of that with every Caterpillar 3306 Engine for sale. Have your mechanic check the arrangement number against your machine before you order.
Shipping a Caterpillar 3306 Engine for Sale Worldwide
We ship every Caterpillar 3306 Engine for sale worldwide. Each engine goes out drained, with openings sealed, bolted or strapped to a strong pallet or skid, and with the pump, turbo and fittings protected.
Sea freight is the normal choice for an engine this heavy. We confirm cost and arrival port before you commit.
You’ll get a commercial invoice, packing list and bill of lading. Your customs broker handles duty and taxes. Engines are classified under the HS system run by the World Customs Organization, so your broker will know the paperwork.
Read our shipping policy for details and our refund and returns policy for what happens if something arrives damaged.
What Arrives on the Pallet
Each Caterpillar 3306 Engine for sale arrives with a copy of the inspection summary, the photos we took before packing and a list of what’s fitted. Check the pallet before you sign for it if you can, and take photos as you unpack. If anything looks wrong, tell us straight away.
Fitting Tips From Heavy-Equipment Mechanics
These are the things good mechanics do when fitting a Caterpillar 3306 Engine for sale:
Fix the cooling system first. Clean or replace the radiator core, check the fan and belts, replace the thermostats and hoses.
Clean the aftercooler and intake if the old engine failed with oil or coolant in the intake.
Transfer parts carefully. Sump, flywheel housing, front drive and mounts may need to come from your old engine.
New filters and fluids. Oil, filters, coolant with the correct additive, and air filters.
Prime the oil system and bleed the fuel before the first start.
Check the rating and settings suit your machine.
Run it in gently and change the oil early.
Looking After the 3306 Once It’s Working
Change the oil and filters on schedule. Machines in dust need shorter intervals.
Service the air filters properly. Dust is the number one killer of earthmoving engines.
Use the right coolant and keep it topped up. Good coolant protects the cylinder walls and prevents corrosion.
Keep radiators clean. Blow them out often on dusty sites.
Idle briefly before shutting down a turbo engine after heavy work.
Don’t turn the pump up. Extra power now means a shorter life later.
Look after it like that, and a good Caterpillar 3306 Engine for sale can give you many thousands more hours.
Questions to Ask Before You Pay
- What’s the arrangement number and serial prefix?
- Is it PC or DI, and is it turbocharged or aftercooled?
- What machine or application did it come from?
- What were the compression, blow-by and oil pressure results?
- Has the pump been adjusted?
- What’s included: pump, turbo, aftercooler, flywheel, housing, sump?
- Is it used, rebuilt or a long block?
- What does the freight quote include?
We answer all of these for each Caterpillar 3306 Engine for sale we list.
Other Heavy-Duty Engines We Supply
For bigger Cat power, see our Caterpillar C15 engine, our C15 problems and solutions guide and the Caterpillar C18 marine engine guide. From other makers, there’s the Cummins M11 engine. Browse all Caterpillar engines or our full used engines range.
For official product information, visit Caterpillar.
Why Buy From NJ Global Auto Parts
We match each Caterpillar 3306 Engine for sale to your machine before you pay. You get real photos, the plate details, a written summary and a clear list of what’s included. We tell you about the flaws as well as the good points, and we quote freight up front, wherever you are.
If we don’t have the right engine, we’ll say so. Read more about us or visit the shop.
Frequently Asked Questions
How big is the Caterpillar 3306?
It’s a 10.5 litre (638 cubic inch) inline six-cylinder diesel.
How much power does it make?
Roughly 150 to 350 hp depending on version, rating and application.
What does DITA mean?
Direct injection, turbocharged and aftercooled.
Is your Caterpillar 3306 Engine for sale used or rebuilt?
We offer both. Each listing and quote says which.
Do you ship to my country?
Yes. We ship worldwide, usually by sea, with freight quoted before you pay.
What if it arrives damaged?
Contact us right away with photos, and we’ll sort it out with you.
A Caterpillar 3306 Engine for sale should come with real photos, the plate details, honest notes and someone who understands heavy diesels. That’s what we give every buyer. Send us your machine model and arrangement number through the contact page, and we’ll tell you what we have and what it’ll cost to get it to you.