Buying Used Outboard Engines

When buying a used outboard engine there are many questions that need to be answered before taking the plunge and spending your hard earned cash. Like buying a used car buying a used outboard engine can be a risky business if you don't know what you are looking for. This guide is intended to help in that process.

OK, first things first, what do you want the engine for? Yes, I know it's for a boat but how big is the boat? How fast do you want to go? Is it for skiing behind? Before spending any money you need to think about exactly what you need from your engine as this may influence the size of engine, whether it is electric start, what the shaft length needs to be, whether it needs hydraulic tilt / trim, whether it is 2 or 4 stroke and how much you need to spend on it. You will see lots of apparently very cheap outboards for sale but be very wary of anything that seems too cheap, they are usually that cheap for a very good reason.

Before you hand over any money please, please check that the engine has not been stolen. Outboard thefts are not that common but they do happen. Fortunately there is a publicly available web site where insurance companies publish the serial numbers and descriptions of any engines that have been reported as stolen. You will find it here: Now it's not 100% because not everybody will have their engine insured or will be able to tell the police the serial number but it is still a very useful tool. If you do buy a stolen outboard it will still be the legal property of the original owner, you could well end up without an engine and seriously out of pocket, so please be careful. Most times the serial number is somewhere near the top of the transom clamp assembly, sometimes it's inside the engine cowling. Most OMC / Johnson / Evinrude engines also have the number imprinted on a small round pressed in cap on the engine block itself.

The very smallest outboard engines are of about 1-2 horse power, these engines are only really useful for very small tenders or rigid inflatable boats (RIBs), they will push you along at a couple of miles an hour on still water but that will be about it. They are usually single speed with reverse being provided by rotating the engine 180 degrees. They are nearly all 2 stroke, typically short shaft and very light in weight – maybe just over 10-12 Kilos. They will run all day on a small tank of fuel but are obviously very limited in power and as they only have one cylinder they are less reliable than there larger multi cylinder counter parts.

Moving up to the 4-6hp range a lot of these engines will be twin cylinders, particularly the older Evinrude, Johnsons and Mercury's. They will weigh a lot more than the 1-2 hp units but will still be easily manageable for the average person. They will be available in long medium and short shaft, this is where you need to know how high your transom is above sea level when your boat is normally loaded. You don't want the engine causing too much drag in the water but you do need enough water over the anti cavitation plate so that the prop doesn't just create a massive rooster tail and not much forward motion. Before you buy a used outboard engine (or a new one for that matter) measure the height of your transom to sea level and select an engine with the correct length of shaft. A 4-6hp engine makes a good size for an aux engine on something up to about 16-18 feet or will propel a small dinghy quite nicely on inland water ways. 8Hp is a very popular choice for RIBs, especially the models with short tiller controls.

Moving up to the 10-15hp range, there is a lot of choice in this range, lots more 4 strokes start to appear at this sort of size, expect them to cost a lot more than their 2 stroke equivalents though. You will also start to find electric start at this sort of size, very convenient if your engine is tricky to get to or if your mobility is less than perfect.

15-30hp is where electric start becomes more of a must have than a desirable feature. You only need this sort of power for larger vessels inland but if going to sea this is really the starting point, in my opinion. It's not funny when you find yourself fighting a tide only to find yourself still going backwards with no throttle left!

40-50hp, this is really the starting point for an outboard engine for a speed boat, some may say you can use smaller but I think 40 is about right for a starter on a 14 ft speed / power boat, it should provide enough power for water skiing. Although you can use pull start this is really the limit before you need electric start, sure it's a lot more money but trying to pull start a 2 cylinder 50hp motor that will be at least 800cc is not much fun, pressing a button is a lot easier. You may also like to consider power trim to get the best performance at all times from a smaller sized motor.

60-100hp This is where you will start to have some serious fun if you have a 16-18ft speedboat. You will need electric start, you will benefit greatly from power trim / tilt, you will also need specialist gear to mount and dismount your motor safely. Outboards have become a lot lighter in recent years but a multi cylinder 100hp engine will still come in at the 350lbs range. It's not unusual for engines of this size to be straight or v6 configurations. A 100hp engine in a 16ft boat should propel it to about 50MPH or more if it is a specially prepared racing hull. Engines of this size will easily pull one or more skiers at enough speed for anybody.

The sky is the limit beyond that, if you want more power than one engine will give you there is always the option to go to multiple engines, I have seen one boat with 5 Mercury Verado supercharged 400hp units on the back. Nice if you have £150,000 to spend!!

So back to the real world, and back to the subject of buying used outboard engines. Once size has been considered, you need to think about budget. Used outboards are for sale all round the country from a few pounds for a bag of scrap at a car boot sale right up to a virtually new multi cylinder state of the art fuel injected power tilt trim with electric start, used only once at well over £10.000. There is everything in between. You should be able to get a very usable outboard engine in most sizes from 2-50hp for between 150 and 1000 pounds. Have a look at our range of engines to see what suits you best.

Think about whether you need electric start, it's a very expensive option, it will add significantly to the price of the engine, you also need a battery and a load of cabling for it. Do you really need it? If so factor it in to the cost. Think about power tilt and trim, again an expensive option but a must have on any outboard engine that weighs over the 250lbs mark. Be sure to measure the required shaft length and buy the right outboard engine for the job.

Fuel consumption may be an issue – power costs money, 4 strokes are typically more economical than 2 strokes, they are however heavier and much more expensive. Modern engines are much better on fuel than older engines but that economy comes at a price, are you going to use your boat enough to justify the extra spend?

Also think about the controls needed for your engine, it might seem daft but these can cost a lot more than you may think, you need to add this to your budget. The very smallest engines will have simple tiller control and maybe just a fuel tap, choke and throttle mounted on either the tiller or the engine itself. If you go to the top of the range you will have a control box with a combined throttle / gear change lever, an ignition switch, safety switch, electric choke control and tilt trim switches. A top of the range controller can cost as much as a 2hp single cylinder engine – daft but true. Also bear in mind that there could be up to a dozen wires that need to go from the engine to the control panel, also not cheap.

The most important thing of all when buying a used outboard engine is to make absolutely sure you know what you are getting for your money. It's fine to buy a bag of bits from a car boot sale at the price of half a barrel of beetroot if you understand it's going to need time and money to get it to a usable condition. If however you spend over £1000 on a 30hp electric start engine that could be 30 years old you need to know it is in good health and ready to go. Unless buying from a reputable dealer always assume that at the very minimum you are going to need to fit a new impeller, change the gear oil and plugs and replace a few seals here and there. If you can always run a compression check to make sure you have about 100-130 psi on each cylinder and that every cylinder is within 10% of it's neighbours. If any pot is down, walk away very quickly, outboard parts are expensive, as is labour. If you don't have a compression tester either borrow one, buy one or find someone that has, this is probably the most important test on a used outboard engine as it's so expensive to put it right, a complete engine strip down being required.

Be sure to check the electrics, including the starter if fitted. Check out the power tilt / trim, this is usually hydraulic. Raise and lower it all the way, leave it at 1/3 tilt up and make sure it does not drop slowly, if it does the hydraulic seals may be gone.>br>
Check the gear case oil – look for signs of the oil going milky, if it is then one or more of the seals have gone and will need to be replaced, if it has been like that for a while the box may be scrap., listen for any nasty grating noises.

Check it goes in and out of gear smoothly, ideally you need to check this on the water. Outboard gearboxes use a thing called a dog clutch, when they get worn they tend to jump out of gear when under load, you can only really test this under power on the water. Just a quick handy hint here – when selecting gear don't be hesitant, put it firmly straight in to gear. Taking your time over it causes excessive wear on the leading edge of the dog clutch and causes it to round off. The clutch is usually made of softer material than the gears it engages with but in extreme cases the gears can be damaged too, replacement is very expensive. It can be a bit disconcerting when an outboard bangs in to gear but it does a lot less harm than riding it.

Check that the engine is cooling properly, on the smallest engine the only evidence will be water mist coming out of the exhaust, put your hand near the exhaust and you should be able to feel it. On the larger engines there will be a “pee hole” where a good jet of water should be being pumped out whenever the engine is running.

If the seller of your outboard engine offers to start it up out of water so you can see it running – walk away!! The only time you can do that is on an air cooled engine, do it on any other engine and the impeller will be destroyed in seconds. If they are prepared to do this for you, they will almost certainly have done it before and have no idea of engine maintenance. An impeller does not cost a lot but can be a pain to change, the biggy though is the damage that can be done to an engine by allowing the resultant over heating – back to the compression test. Always have a look at the power head (engine block), if the paint is peeling off it has probably been over heated.

All our used outboard engines are fully serviced and test run either in water or on flush muffs, all impellers are checked / changed without exception. All engines are set up according to the manufacturer's specifications. It really is worth spending a bit more money before relying on your engine to get you back in to harbour against a retreating tide.

I hope this guide has been useful, I will update and improve it as time goes by. I hope you enjoy your boat, treat your boat and engine well and they will look after you.
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