Used Outboard: What to Check Before You Buy

There are many ways to find and buy a used outboard, especially if you’re shopping online. 

You’ve shopped around and settled on a used outboard the seller says is ready to run. In other words, not a fixer-upper you know is going to need work, but rather an outboard motor you can expect to take home, mount on your boat and go. However, before you buy a used outboard, you should obviously check out the motor and make sure it runs before any money changes hands. Watch the video above or read on below to find out about 10 ways to evaluate a used outboard.

Evaluating a Used Outboard Motor Checklist

Used Outboard Check 1: Making Sure the Outboard Fits

The first thing you need to check is whether or not the motor will actually fit your boat. 

How to evaluate a used outboard motor

Outboard motors come in different shaft lengths to accommodate varying transmission heights, so you need to make sure the motor you’re eyeing will actually work with your boat.

The best way to check if it’ll fit is to measure from the top of the transom down to the lowest part on the hull. This measurement needs to match the measurement from the clamp on the outboard down to the cavitation plate. That’s the shaft length, which is generally measured in 5-inch increments. Those measurements need to line up to know if the outboard will fit without having to swap out the midsection and the drive shaft inside.

Used outboard what to check measurement

Used Outboard Check 2: Visual Inspection for Damage

Give the outboard motor a thorough visual inspection. Check out the cowl to make sure it’s undamaged and in good condition. If the cowl looks brand new, make sure to ask why. Inspect the propeller for damage and for debris around the shaft. Check the prop and the anodes for corrosion.

Used Outboard Check 3: Checking the Lower Unit Oil

While you’re focused in on the lower unit, open the drain bolt for a second and look at the oil that comes out of it. If the oil is black, it’s a good sign. However, if the lower unit oil is cloudy or milky, there’s a problem with the seals and possibly water intrusion.

How to evaluate a used outboard lower unit oil

Keep in mind that if the oil is brand new, you can’t really tell if there’s a leak or not. The oil could’ve been changed out the day before, so you’ll also want to check for excess metal shavings on the drain bolt. A little bit of metal shavings on the bolt is normal wear and tear, but if the shavings are excessive, chances are there’s a problem with the engine.

Used Outboard Check 4: Asking About the Water Pump

Make sure to ask the seller about the water pump, especially about the last time it was changed. If the seller can tell you about the condition of the water pump, you might get a better idea of how well the motor has been taken care of.

Used Outboard Check 5: Inspecting the Cowl Gasket

After giving the lower unit a close inspection, pull the cowl from the powerhead and look at the gasket at the base of it to see if it’s firmly sealed in place. Also check it for wear because if it’s worn out, that means water could have gotten past the cowl and damaged the outside of the engine. 

Used outboard motor evaluation cowl inspection

Used Outboard Check 6: Pulling the Dipstick

Before you actually run an engine, it’s good to know more about what’s going on inside of it. The easiest way to do that if you’re dealing with a 4-stroke is to pull the dipstick and look at the oil. Not only are you making sure there’s actually oil in it, but you want to know what it look likes too. As with the lower unit oil, milky or cloudy engine oil is a bad sign; dark oil is a good sign; and new oil at least shows that it’s been changed recently.

Used outboard evaluation engine oil

Used Outboard Check 7: Inspecting the Spark Plugs

Pull the spark plugs and check if they look oily or have metal shavings on them, which are really bad signs. If the plugs are dark, the motor may be running a bit rich, which is not a huge deal. However, really light plugs can mean the motor is  running lean, which is typically a sign that it’s been operating a little too hot. 

Used outboard evaluation spark plugs

Used Outboard Check 8: Doing an Outboard Compression Test

As you’re getting the spark plugs back in, it’s the perfect time to run a compression test on the outboard. A compression test is probably the single most important thing you can do outside of running the outboard motor to tell you if it’s worth the money. 

Used outboard shopping evaluation compression test

You’ll need to know a little about what the specs associated with the cylinders on that specific engine are, but what you’re really looking for is consistency. The numbers may be a little lower than the factory spec because of wear, but don’t let that scare you away. However, if the cylinders vary more than 5 or 10 PSI between them, it’s a sign that something’s really wrong and you should avoid buying that outboard engine.

Used Outboard Check 9: Taking a Test Run

After inspecting the used outboard motor, give it a test run if you can, especially if it’s still attached to a boat you can get in the water. Otherwise, put some muffs on it and run it on land, but keep in mind that it might run a little rougher than it would in the water since there’s less backpressure on the exhaust. Check if the motor starts easily, and whether it cranks right up or takes a little bit of work to get going. Feel how it runs once it gets going, and check for smoke and odd smells.  

Buying a used outboard tips

Used Outboard Check 10: Checking Controls Compatibility

From a price standpoint, it’s good to make sure the particular engine you’re looking at has the right controls for your boat. In other words, the controls you have might not work with the motor you’re getting. And if they’re not compatible and you’re not getting the controls with the outboard, you’re going to have to spend additional money to buy compatible controls before you get out on the water. 




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