MERCURY 5 HP 5MH-LPG PROPANE OUTBOARD MOTOR

Description

The Mercury 5 HP 5MH-LPG propane outboard motor runs on propane instead of gasoline. No fuel to go stale, no carburetor full of varnish after the winter, no spilled gas in the boat. Just clip on a propane cylinder, pull the cord and go. We have it for sale new, with the Mercury factory warranty, and we ship it worldwide.

Propane outboards are still new to a lot of people, so I’ll explain how this one works, who it really suits, and the few things you need to know before you buy. If you’ve ever pulled a cord fifty times on a spring morning because last year’s fuel went bad, you’ll probably like what you read.

On this page:

• Why a propane outboard
• How the Mercury 5 HP 5MH-LPG propane outboard motor works
• Boats it suits
• On the water
• Features
• Specifications
• Maintenance
• Buyer questions
• Propane vs gasoline
• Price and shipping
• FAQ

Why a propane outboard?

Most small outboard problems come down to fuel. Gasoline breaks down over time, especially fuel with ethanol in it. Leave it in a small carburetor for a few months and it leaves gum and varnish in the tiny jets. Next time you want to use the motor, it won’t start, or it won’t idle, and you end up cleaning the carb or paying someone else to.

The Mercury 5 HP 5MH-LPG propane outboard motor sidesteps all of that. Propane doesn’t go stale. It doesn’t gum anything up. You can leave the motor in the shed for a year, connect a cylinder and it’ll start. For people who only use their boat a few times a season, that alone is worth the price.

There are other advantages too. Propane burns cleanly, so there’s less smell and less residue. There’s no liquid fuel sloshing around in the boat or leaking onto the floor of your car. And propane cylinders are easy to find in many parts of the world, from camping shops to hardware stores. Some lakes and reservoirs also restrict or discourage gasoline, and a propane motor can be a good fit there. Always check the local rules where you boat.

How the Mercury 5 HP 5MH-LPG propane outboard motor works

Mechanically, it’s the same trusted 5 hp four stroke Mercury builds for gasoline, with a 123 cc single cylinder and a pressurised oil system. The difference is the fuel system. Instead of a carburetor and gas tank, it has a propane regulator and a fuel supply line that connects to an external propane cylinder.

There’s no built in fuel tank on this version, which is why the spec sheet lists the fuel tank as external. You supply the propane in a standard cylinder, either a small disposable camping style bottle for short trips, or a larger refillable tank for longer use, connected with the correct adapter and hose. We’ll talk you through the right setup for your country when you order.

The model code breaks down like this: 5 is the horsepower, M is manual start, H is tiller handle, no L means a 15 inch short shaft, and LPG means liquefied petroleum gas, or propane. There’s also a long shaft version, the 5MLH-LPG.

Boats the Mercury 5 HP 5MH-LPG propane outboard motor suits

Measure your transom first. About 15 inches from the top of the transom to the bottom of the hull means this short shaft motor is right. About 20 inches means you want the long shaft LPG version.

• Small aluminum fishing boats and car toppers around 10 to 12 feet
• Jon boats with low transoms
• Inflatables and RIBs up to around 3.5 metres
• Hard dinghies and tenders
• Small boats kept at a cabin or lake house and used only occasionally

That last group is the perfect buyer. If your boat sits for long stretches between uses, the Mercury 5 HP 5MH-LPG propane outboard motor removes the biggest reason small motors fail to start.

Performance is similar to the gasoline 5 hp. It pushes a small aluminum boat at a comfortable displacement speed and trolls smoothly. On a light inflatable with one person it can sometimes get close to planing. For more speed on a bigger boat, look at the 8MH or 9.9MH.

Running the Mercury 5 HP 5MH-LPG propane outboard motor

Starting

Connect the propane supply, open the cylinder valve, put the motor in neutral, clip on the lanyard and pull. Propane starting is usually very easy because there’s no carburetor to flood or gum up. The start in gear protection means it won’t start in forward or reverse.

Gears and steering

Forward, neutral and reverse, with the shift lever mounted on the front of the motor. Steering tension is adjustable and the twist grip throttle has a friction knob so you can set a speed and let go.

Shallow water drive and trim

Six trim positions and a shallow water drive setting let you run the prop higher when you’re creeping over weed, sand or rocks at low speed.

Noise and emissions

Exhaust goes out through the prop hub. It’s quiet, and propane burns cleanly, so there’s very little smell.

RPM

Full throttle sits at 4,500 to 5,500 rpm. Speed depends on your boat and load.

Mercury 5 HP 5MH-LPG propane outboard motor features

• Runs on propane (LPG) from an external cylinder
• Compact and lightweight, about 55 lb
• Digital CD ignition with spark advance
• High grade marine alloy construction
• Stainless steel water pump housing
• Zinc coated water passages
• Rated for saltwater use
• Sacrificial zinc anodes
• Forward, neutral and reverse gear shift
• Forward mounted gear shift selector
• Adjustable steering tension control
• Twist grip throttle with tension control
• Integrated carry handle
• Thermostat controlled water cooling
• Shallow water drive with 6 trim positions
• Quiet through propeller hub exhaust
• Start in gear protection
• Low oil pressure warning indicator
• ESG over rev protection
• Safety lanyard stop switch
• Owner’s manual
• Mercury Marine 3 year warranty

Mercury 5 HP 5MH-LPG propane outboard motor specifications

For Mercury’s own information on their small outboards, including the propane models, see their FourStroke outboards page. If you need a detail confirmed for the exact unit, ask us.

Maintaining the Mercury 5 HP 5MH-LPG propane outboard motor

Maintenance is simpler than on a gasoline motor, because there’s no carburetor to clean and no stale fuel to worry about. The rest is standard small four stroke care.

Propane connections

Check the hose and fittings for cracks, wear or damage before each use. Keep the connection clean and dry. Close the cylinder valve when you’ve finished for the day. Store cylinders upright in a ventilated place, never in a closed cabin or hold.

Oil

About 450 ml of 10W-30. Check the dipstick before each outing. First change at 20 hours, then every 100 hours or once a season.

Gear case

Change the gear lube every year and check for milky lube, which means water getting in.

Cooling and salt

Watch for the telltale water stream every time the Mercury 5 HP 5MH-LPG propane outboard motor starts. Flush after saltwater use and check the anodes.

For general boating safety, the US Coast Guard boating safety site is a clear, practical resource wherever you are.

Questions buyers ask about the Mercury 5 HP 5MH-LPG propane outboard motor

“Is propane as powerful as gasoline?”

For everyday use on a small boat, you won’t feel much difference. The Mercury 5 HP 5MH-LPG propane outboard motor uses the same proven 5 hp powerhead and propeller setup, so it pushes a small boat in much the same way. What you notice more is how easily it starts and how clean it runs.

“How long does a propane cylinder last?”

It depends on the cylinder size, how hard you run the motor and how long you’re out. Small disposable camping cylinders are handy for short trips but won’t last a long day. A larger refillable cylinder, sized to suit your boat and how you use it, is the better choice for regular use. Many owners carry a spare small cylinder as backup. We’re happy to suggest a sensible size when you tell us how you plan to use the Mercury 5 HP 5MH-LPG propane outboard motor.

“Is propane safe on a boat?”

Used sensibly, yes. Propane is heavier than air, so the golden rule is to keep cylinders in an open, ventilated spot where any leak can drain overboard, never in a closed cabin, locker or bilge. Check hoses and fittings before each trip, close the cylinder valve when you’re done, and follow the owner’s manual and any local regulations. Treat it the same way you’d treat a propane barbecue or camping stove.

“Can I find propane where I live?”

In most countries, yes. Camping cylinders and refillable tanks are widely available, although the fittings and cylinder sizes differ from country to country. That’s why we don’t ship a cylinder with the motor. Tell us where you are and we’ll point you in the right direction on adapters.

“Does it need a battery?”

No. The Mercury 5 HP 5MH-LPG propane outboard motor is pull start with no internal battery. Nothing to charge, nothing to go flat.

“Is it harder to service?”

In most ways it’s easier. There’s no carburetor to strip and clean, no fuel filter clogged with old gas. Oil changes, gear lube, spark plug and impeller are the same as on the gasoline motor.

Who gets the most out of a propane outboard

From what we’ve seen, three types of owner get the most from the Mercury 5 HP 5MH-LPG propane outboard motor.

The first is the occasional boater. Someone with a small boat at a holiday cabin who uses it a few weekends a year. With a gasoline motor, every visit starts with a battle against stale fuel. With propane, it just starts.

The second is the person who already uses propane. If you’ve got a camper van, an RV, a boat with a galley stove or a big barbecue, you already understand propane and you probably already have cylinders on hand. Adding a propane outboard fits right in.

The third is the boater on a lake or reservoir where gasoline is restricted, discouraged or simply awkward to carry. Always check local rules, but propane can make life easier in those places.

Setting up the Mercury 5 HP 5MH-LPG propane outboard motor

When it arrives, check the motor over for any shipping damage and let us know straight away if something isn’t right. Check the engine oil on the dipstick and top up if needed.

Clamp the motor to the centre of the transom, tighten both clamp screws firmly by hand and tie a safety line from the motor to the boat. Set the tilt pin so the motor sits roughly upright in the water with the boat loaded as normal.

Now the propane. Place the cylinder somewhere open and secure in the boat, where it can’t roll around and where any leak would vent overboard. Connect the fuel supply line using the correct adapter for your cylinder, and make sure the connection is tight and clean. Open the cylinder valve slowly. If you smell gas at the connection, close the valve and check the fitting before going any further.

Clip the lanyard to yourself, put the motor in neutral and start it. Let it idle for a minute and check the cooling water telltale. For the first couple of hours, vary the throttle rather than running flat out. Change the oil after the first 20 hours.

Storage made simple

This is where the Mercury 5 HP 5MH-LPG propane outboard motor really shows its worth. With a gasoline motor, a proper lay up means running the carb dry, draining the tank and adding stabiliser. With propane, you close the cylinder valve and disconnect the line. That’s the fuel system done.

For the rest, flush the cooling system with fresh water, change the oil and gear lube, grease the swivel and clamp screws, and store the motor upright or on its correct side in a dry place. Store the propane cylinder separately, outside or in a well ventilated space, as you would any gas bottle.

When the next season comes around, reconnect the cylinder, check the oil and start it. No carb cleaning, no fresh fuel runs to the petrol station, no hours of pulling the cord. That’s really the whole point of a propane outboard.

A word on the environment

Propane burns more cleanly than gasoline, and there’s no risk of spilling liquid fuel into the water when you refuel. For people who boat on small, sensitive lakes or drinking water reservoirs, that matters. It’s one more reason some owners choose the Mercury 5 HP 5MH-LPG propane outboard motor even when they boat regularly.

Real uses we’ve seen for this motor

One of our buyers keeps a small aluminum boat at a lake cabin that the family visits maybe six times a year. For years, the first morning of every visit was spent fighting an old gasoline motor that had sat with fuel in it. He switched to the Mercury 5 HP 5MH-LPG propane outboard motor and told us the first start of the season now takes a couple of pulls instead of a couple of hours.

Another customer uses one on an inflatable tender for a motorhome road trip. The motorhome already runs on propane for cooking and heating, so they carry one type of fuel for everything. The inflatable and motor pack into the garage of the motorhome, and the motor never smells of gasoline inside the vehicle.

A small fishing club bought a pair for their members’ rowing boats on a reservoir where they preferred members not to carry gasoline. The motors sit in a shed between uses and start reliably whenever someone wants them.

The pattern is always the same. People who don’t use their motor every week, or who want to avoid liquid fuel, get a lot out of propane.

Spares worth keeping in the boat

Keep a spare spark plug and spanner, a shear pin or prop hardware, a small bottle of engine oil, a spare lanyard and a spare O ring or seal for your propane connector. Pack them in a dry bag. With those, you can deal with nearly every small problem on the water and keep the Mercury 5 HP 5MH-LPG propane outboard motor running all season.

Paperwork, warranty and keeping records

When your Mercury 5 HP 5MH-LPG propane outboard motor arrives, write down the serial number and keep it with your invoice. Take a photo of the serial plate on your phone too. If you ever need warranty work, a dealer will ask for both, and it makes the process much quicker. The Mercury factory warranty starts from the date of purchase, so hang on to that paperwork.

It is also worth keeping a simple log: date, engine hours if you have them, oil changes, gear lube changes, impeller replacements and anything unusual you noticed. It takes seconds after each service, and it adds real value if you ever sell the boat. Buyers pay more for an engine with a clear service history, and it helps any mechanic you work with understand the motor quickly.

Check your boat insurance as well. Many policies have specific requirements for outboard security, such as a lock on the clamps or bracket, and some ask for the serial number. Better to sort that out on day one than find out after a problem.

Propane vs gasoline: which 5 hp should you buy?

Choose the Mercury 5 HP 5MH-LPG propane outboard motor if you use the boat occasionally, hate dealing with stale fuel, want a cleaner running motor, or boat somewhere gasoline is restricted.

Choose the gasoline Mercury 5MH if you use the boat often, want the convenience of a built in tank, or you’ll be somewhere propane cylinders are hard to get.

Other options: the 5MLH-LPG long shaft propane, and the 5MLHA-LPG Sail Power for sailboats. See the whole range in our Mercury outboard motors category and the 6 HP section.

Mercury 5 HP 5MH-LPG propane outboard motor for sale: price and worldwide shipping

The price of the Mercury 5 HP 5MH-LPG propane outboard motor is at the top of this page. Buy it through the cart, or contact us for a delivered quote.

In the box

• Mercury 5 HP 5MH-LPG propane outboard motor, new
• 3 blade aluminum propeller, fitted
• Propane fuel supply line
• Owner’s manual
• Mercury Marine 3 year factory warranty from the date of purchase

The propane cylinder isn’t included, as cylinders and fittings differ by country and can’t be shipped with the motor. We’ll advise on the right cylinder and adapter for where you live.

Shipping

We ship worldwide by courier or freight, securely packed, with tracking. Import duty and taxes vary by country, and we’ll explain what to expect before you pay.

Buying from us

Read our refund and return policy, see our customer reviews, and learn about us on the about page.

Mercury 5 HP 5MH-LPG propane outboard motor FAQ

Does it come with a propane tank?

No. It comes with the fuel supply line. You supply the cylinder, and we’ll help you choose one.

Does it have reverse?

Yes, forward, neutral and reverse.

How heavy is it?

About 55 pounds.

Does it charge a battery?

No, this model has no alternator.

Is it new?

Yes, new with the Mercury factory warranty.

Do you ship worldwide?

Yes. Tell us your country for a delivered price.

Order your Mercury 5 HP 5MH-LPG propane outboard motor

No stale fuel, no gummed up carb, no spilled gasoline. If that sounds good, the Mercury 5 HP 5MH-LPG propane outboard motor is for you. Add it to your cart, or send us a question first. You can also browse all our outboard motors for sale.