Lycoming O-Series Engine Overhaul Cost

That moment hits every aircraft owner eventually. You check your logbooks, look at the hours, and realize your engine is getting close to overhaul time. Your stomach drops a little. How much is this going to cost?

If you fly behind a Lycoming O-Series engine, you're in good company. These engines power some of the most popular planes in general aviation. The O-235, O-320, O-360, and O-540 have been flying for decades. Did you know that The O-320 was introduced in 1953 and remains in production today; they're known for being tough and reliable. But even the best engines need a major overhaul eventually.

Here's the thing about Lycoming O-Series overhaul cost: the numbers can vary a lot. You might hear one pilot say they paid $25,000. Another says they spent $50,000. Both can be telling the truth. The final price depends on many factors. 

What condition is your engine in? Which shop do you choose? Do you want new cylinders or overhauled ones? These choices add up fast.

The good news is that you can plan for this expense. When you understand what goes into an overhaul, the costs make more sense. You can budget smarter. You can ask better questions. You can avoid surprises that blow up your maintenance fund.

To start, let's go over what makes the O-Series special and which planes use these popular engines.

Key Takeaways

A typical Lycoming O-Series engine overhaul costs between $25,000 and $55,000 for four-cylinder models and $45,000 to $80,000 for six-cylinder models when you include all expenses. The base overhaul price is only part of the story. You also need to budget for engine removal, new hoses, accessory overhauls, and shipping. Your final cost depends on your engine model, the shop you choose, and the condition of your internal parts.

The Lycoming O-Series: A Quick Overview

The Lycoming O-Series is a family of four-cylinder and six-cylinder engines that have powered general aviation for over 70 years. The "O" stands for horizontally opposed. That means the pistons sit across from each other, like two boxers facing off. This design keeps the engine compact and helps it run smoothly.

These are carbureted engines. They use a carburetor to mix fuel and air before it enters the cylinders. They're also naturally aspirated, which means they don't have a turbocharger. Simple and reliable is the name of the game here.

The Main Models

The O-Series includes four main engine families:

• O-235 (115–125 horsepower): The smallest of the bunch. You'll find it in trainers like the Cessna 152 and Piper Tomahawk.
• O-320 (150–160 horsepower): This one powers the Cessna 172 from the late 1960s through the 1980s. It also runs the Piper Cherokee 140 and Piper Warrior. Many consider it one of the most bulletproof engines ever made.
• O-360 (180 horsepower): A step up in power. It's in the Piper Cherokee 180, Piper Archer, and newer Cessna 172 models. Very popular with owners who want a balance of power and efficiency.
• O-540 (235–260 horsepower): The big six-cylinder option. You'll see it in the Piper Cherokee Six, Piper Saratoga, and Piper Dakota. More power means more airplane, but also higher overhaul costs.

What About Fuel-Injected Versions?

You might notice some engine designations start with "IO" instead of "O." The IO-360 is a good example. That "I" means fuel-injected. These engines skip the carburetor and use a fuel injection system instead. They cost a bit more to overhaul because the fuel system is more complex. But the core engine is the same basic design.

Why These Engines Are So Popular

Lycoming introduced the O-320 back in 1953. That's over 70 years of production. These engines have proven themselves millions of times over. Parts are easy to find. Mechanics know them inside and out. When something does go wrong, the fix is usually straightforward.

The O-Series also has a huge installed base. Tens of thousands of these engines are flying right now. That means plenty of shops compete for your business. Competition helps keep prices reasonable. It also means you have choices when overhaul time comes.

Understanding which engine you have is the first step in planning your overhaul budget. Check your data plate to confirm your exact model. The numbers and letters matter because different variants have different parts and different costs.

When Does Your Engine Actually Need an Overhaul?

This is one of the most common questions aircraft owners ask. The answer isn't as simple as you might think. There's what Lycoming recommends, what the FAA requires, and what actually makes sense for your situation.

Understanding TBO

TBO stands for Time Between Overhaul. For most Lycoming O-Series engines, the recommended TBO is 2,000 hours or 12 years. Whichever comes first. Lycoming publishes these numbers in Service Instruction 1009.

Here's something many owners don't realize: TBO is a recommendation, not a legal requirement. If you fly under Part 91 (private, non-commercial operations), you can legally fly past TBO. The FAA doesn't mandate overhaul at any specific time for Part 91 operators.

That said, there are good reasons to take TBO seriously. Insurance companies pay attention to engine time. Buyers care about it when you sell. And the recommendation exists because Lycoming knows how long these engines typically last before problems start showing up.

Calendar Time Matters More Than You Think

Many planes don't fly 2,000 hours in 12 years. A typical owner might put 50 to 100 hours per year on their engine. At that rate, you'd hit 12 years long before you hit 2,000 hours.

Why does calendar time matter? Because engines that sit have problems that flying engines don't. Moisture builds up inside. The camshaft and lifters lose their protective oil coating. Rust starts to form. Seals and gaskets dry out and crack.

An engine with 800 hours that's been sitting for 10 years might actually be in worse shape than one with 1,800 hours that flies every week. The 12-year calendar limit exists to catch these low-use engines before corrosion causes a failure.

Signs Your Engine Might Need Attention Sooner

Sometimes an engine tells you it needs help before TBO arrives. Watch for these warning signs:

• Compression dropping on one or more cylinders
• Oil consumption increasing beyond normal levels
• Metal in the oil filter or on the screen
• Unusual noises or vibrations
• Oil analysis showing elevated wear metals

If you see any of these, talk to your mechanic. You might need a top overhaul (just the cylinders) or a full major overhaul. Catching problems early can actually save money. A spalled camshaft caught at 1,500 hours is expensive. A spalled camshaft that takes out your crankshaft at 1,800 hours is much worse.

The "On Condition" Approach

Some owners choose to fly past TBO and monitor their engine closely. This is called flying "on condition." They watch compression numbers, oil analysis results, and filter contents like a hawk. As long as everything looks good, they keep flying.

This approach can work, but it requires discipline. You need to do oil analysis at every oil change. You need to document everything. And you need to be honest with yourself when the numbers start trending the wrong way.

Factory vs. Field Overhaul: What's the Difference?

When overhaul time comes, you have two main paths. You can send your engine to Lycoming's factory in Williamsport, Pennsylvania. Or you can use an independent overhaul shop, often called a field overhaul. Both options can give you a reliable engine, but they work differently and cost differently.

Factory Options from Lycoming

Lycoming offers three types of engines from their factory:

Factory New – Every single part is brand new. The engine has zero time since new. This is the most expensive option by far. Think $100,000 or more for many models. Most owners only consider this for special situations.

Factory Rebuilt – The engine is completely disassembled. Every part must meet new manufacturing specifications. Some parts might be used, but they measure the same as new parts. The engine gets a new data plate and a new logbook showing zero time. Only Lycoming can legally "rebuild" a Lycoming engine to zero time. This typically costs 50–70% more than a field overhaul.

Factory Overhauled – Parts must meet service limits, which allow a bit more wear than new limits. The engine keeps its original total time but shows zero time since major overhaul. This costs less than a rebuild but more than most field overhauls.

What Is a Field Overhaul?

A field overhaul is done by an independent shop rather than the factory. These shops range from small local operations to well-known names like Penn Yan, Zephyr, and Western Skyways. They follow Lycoming's overhaul manual and must meet FAA standards.

During a field overhaul, your engine is completely torn down. The crankshaft gets inspected and measured. The crankcase gets checked for cracks. Bearings, gears, and other internal parts get examined. Many parts get replaced with new ones. Others get reconditioned if they're still within limits.

When finished, your engine shows zero time since major overhaul. But the total time keeps counting from where it was. A field-overhauled engine is not "zero-timed." Only the factory can do that.

New Limits vs. Service Limits

Here's an important detail many owners miss. An overhaul can be done to "new limits" or "service limits."

New limits means every reused part must measure within the same tolerances as a brand-new part. If a part has worn even slightly beyond new specs, it gets replaced or reconditioned.

Service limits means parts can have more wear and still be reused. A part might be a few thousandths of an inch past new specs but still within the allowed service range.

New limits overhauls cost more but give you a tighter engine that should last longer. Most quality shops do new limited overhauls as their standard. Be suspicious of quotes that seem too low. They might be using service limits and not telling you.

What Gets Replaced?

A proper overhaul replaces many engine parts regardless of condition. Lycoming's Service Bulletin 240 lists mandatory replacement items including:

• Exhaust valves and valve guides
• Hydraulic lifters
• All gaskets and seals
• Bearing sets
• Connecting rod bolts
• Spark plugs and ignition harness
• Magneto points and condensers (or complete magneto overhaul)

Most shops also replace the camshaft and lifters with new parts. Lycoming cylinders or aftermarket cylinders are often new rather than overhauled. The fuel pump typically gets overhauled or replaced. Same with the carburetor or fuel injection system.

Making the Choice

Factory engines make sense when your core has problems. If your crankshaft or crankcase is likely damaged, the factory absorbs that risk with their flat pricing. You know exactly what you'll pay.

Field overhauls make sense when your engine has good bones. A first-run engine with a solid crankshaft and crankcase will cost less at a quality field shop. You keep your original parts with known history. And you often get a better warranty from the top independent shops than from the factory.

How Much Does It Really Cost to Overhaul a Lycoming O-Series Engine?

Now we get to the heart of the matter. What will you actually pay when your Lycoming engine needs a major overhaul? The answer has two parts: the base overhaul price and all the extra costs that come with it. Here’s a closer look at both so you get the complete picture.

Base Overhaul Prices by Model

Different engines cost different amounts to overhaul. Bigger engines have more parts. More complex engines take more time. Here's what you can expect to pay for the engine work itself at a quality field shop in 2025:

Why such a wide range? Several factors affect the price:

• Shop reputation – Well-known shops charge more but often deliver better results
• Cylinder choice – New Lycoming cylinders cost more than overhauled or aftermarket options
• Parts quality – New camshaft and lifters versus reconditioned ones
• Geographic location – Shops in high-cost areas charge more for labor
• Current demand – Busy shops can charge premium prices

A budget shop might quote you $25,000 for an O-360. A premium shop might quote $38,000 for the same engine. Both can be legitimate quotes. The difference comes down to what's included, the parts they use, and the warranty they offer.

What's Included in a Typical Quote?

Before comparing prices, you need to know what each shop includes. A good engine overhaul quote should cover:

Standard Inclusions:

• Complete disassembly and cleaning
• Crankshaft inspection, measurement, and regrinding if needed
• Crankcase inspection and crack testing
• New bearing sets throughout
• New piston rings (sometimes new pistons)
• New or overhauled cylinder assemblies
• New camshaft and lifters
• New exhaust valves and valve guides
• New gaskets and seals
• Magneto overhaul or replacement
• Carburetor or fuel injection overhaul
• New spark plugs and ignition harness
• Fuel pump overhaul or replacement
• Assembly, test run, and break-in
• New logbook for the overhauled engine

Some shops include dynamic balancing. This makes the engine run smoother. Others charge extra for it. Ask specifically.

The Hidden Costs Nobody Mentions

Here's where many owners get surprised. The base overhaul cost is only part of your total bill. You also need to pay for everything around the engine work. These costs add up fast.

Engine Removal and Reinstallation

Someone has to take the engine off your airplane and put it back on later. This labor typically costs $2,000 to $5,000 depending on your aircraft and local shop rates. A simple Cessna 172 is on the lower end. A complex twin is on the higher end. If you want to learn more about what this involves for one of the most common trainers, check out Cessna 172 Engine Overhaul Time and Cost Explained for Plane Owners.

Hoses and Lines

All the flexible hoses connected to your engine should be replaced at overhaul. Oil hoses, fuel hoses, and breather lines get brittle with age. Many shops will void your warranty if you don't replace them. Budget $1,500 to $2,500 for a complete hose kit.

Oil Cooler

Your oil cooler has tiny passages that collect debris over thousands of hours. A new or overhauled oil cooler costs $800 to $1,500. Some owners skip this, but it's a risk. Contamination from an old cooler can damage your fresh engine.

Propeller Governor

If you have a constant-speed propeller, the governor should be overhauled while the engine is off. This costs $800 to $1,200. Doing it now saves labor later.

Baffles

The sheet metal baffles around your engine direct cooling air. After years of service, they get cracked and bent. Baffle seals wear out. Plan on $500 to $1,500 for baffle repairs and new seals.

Exhaust System

Your exhaust pipes, muffler, and heat shroud take a beating. Cracks are common. A thorough inspection might reveal problems. Repairs or replacement can run $500 to $3,000 depending on what's needed.

Engine Mount

While the engine is off, your mechanic can inspect the mount properly. Lord mounts (the rubber shock absorbers) should be replaced. Budget $200 to $800 for mount work.

Shipping

If you send your engine to an out-of-state shop, shipping costs money. Expect $600 to $1,200 for round-trip freight on a crated engine. Some shops include shipping in their quote. Others don't.

Sales Tax

Depending on your state, you might owe sales tax on the entire job. At 6-8%, that adds $1,500 to $3,000 on a typical overhaul.

Adding It All Up

Let's look at a realistic total for a common engine like the O-360:

That's a realistic number for a quality overhaul with no major surprises. If your crankshaft turns out to be damaged, add another $7,000 to $10,000. If your crankcase is cracked, that's another $3,000 to $8,000.

What About Factory Pricing?

Lycoming factory options cost more but offer some advantages. A factory overhauled O-360 runs around $55,000 to $65,000 plus core charge. A factory rebuilt version costs $70,000 to $85,000 plus core.

The factory price includes everything needed to build the engine. If your core has a bad crankshaft, the factory absorbs that cost. You pay the quoted price regardless of what they find. This certainty has value when your engine has unknown history.

Factory engines also come with FAA-approved documentation that some buyers value highly. All engine parts meet strict traceability requirements. For more on why documentation matters, see How to Verify Traceability and Certification of Used Aircraft Parts.

For a four-cylinder aircraft engine like the O-320, O-360, or IO-360, budget $30,000 to $55,000 total. The range depends on your shop choice, parts selection, and what surprises show up during teardown.

For a six-cylinder O-540, budget $45,000 to $80,000 total. The bigger engine has more parts, takes more labor, and costs more for everything from cylinders to shipping.

These numbers might seem high. But spread over 2,000 hours of flying, even a $50,000 overhaul works out to $25 per flight hour. That's part of the cost of aircraft ownership. Plan for it, budget for it, and it becomes manageable.

Conclusion

Planning for your Lycoming O-Series engine overhaul doesn't have to be stressful. Now you know the real numbers. Four-cylinder engines typically cost $30,000 to $55,000 all-in. Six-cylinder engines run $45,000 to $80,000. The exact price depends on your engine model, the shop you choose, and what your internals look like when they crack open the case.

The key is planning ahead. Start setting money aside before you reach TBO. Get multiple quotes from reputable shops. Ask detailed questions about what's included. Understand the difference between factory and field options. Know that hidden costs like removal, hoses, and accessories can add $5,000 to $15,000 to your base quote.

Your engine is the heart of your airplane. Taking care of it means taking care of yourself and everyone who flies with you. With the right preparation, you can handle this major expense and get back in the air with confidence.

Want more guidance on aircraft ownership, maintenance costs, and smart buying decisions? Flying 411 has you covered with straightforward information to help you fly smarter.

Frequently Asked Questions

Can I overhaul my Lycoming engine myself?

Legally, an A&P mechanic with Inspection Authorization must supervise and sign off the work. Some owners do "owner-assisted" overhauls where they help with disassembly and cleaning under mechanic supervision. This can save some labor costs but requires significant time and mechanical ability.

How long does a Lycoming engine overhaul take?

Most shops quote 8 to 16 weeks for a complete overhaul. Add time for shipping both ways. Some shops have longer backlogs, especially for popular engine models. Factory overhauls can take 4 to 6 months or longer depending on demand and parts availability.

Does an overhaul increase my airplane's value?

Yes, a fresh overhaul typically adds significant value. Buyers pay more for low-time engines. However, you rarely recover 100% of your overhaul cost in the sale price. The value boost depends on overall aircraft condition and market demand.

What happens if my crankshaft is bad during overhaul?

A damaged crankshaft adds $6,000 to $10,000 to your bill at a field shop. This is why some owners choose factory options. Factory pricing includes the crankshaft risk. With a field overhaul, you pay extra if yours doesn't pass inspection.

Should I overhaul or buy a different airplane?

This depends on your airplane's overall value and condition. If overhaul costs approach 30-40% of the aircraft's value, some owners sell and buy a plane with a fresh engine. Do the math for your specific situation before deciding.