How to survey an outboard?
 

I have a close friend that is buying a 10 year old sea-ray (18') with a 120 Hp outboard engine on it. I am wondering what he/I can look for on the engine to tell what condition it is in.

Can you do a compression check on a 2 cycle? what about a leak down test? I can check the spark plugs but what else is there?

The dealer says he doesn't have the scanner for the hours he says his best guess is about 150 hours. Yeh right I can see another new boater being screwed big time.

Any help would be appreciated.

You can run compression checks on PWC motors, so I would imagine you can on outboards.

That's it, just exhausted my knowledge on outboards. :D

Compression and or leak down is the first thing to check depending on the make and model will determine compression, they should all be close the #'s, check lower unit. good luck

What kind of motor?

Not sure on the motor (Engine) ;) yet I am going to check it out in a few minuites. It's on my way home.

I just seen it, they had it in the water so I could not see the hull. The motor is a 115 Hp Merc. It was running when I got there. at idle it was shakin pretty hard. it must of been missing pretty good. There was a tech working on it. I asked him what he done to the engine he said not much. Jut prepping it. I asked him how the lower unit fluid looked. "He said is that the green stuff?" He said it looked good though. I asked him how long he has been working on boats he said two months. This is the "Tech" that has gone through the engine as described to the sales person to the buyer.

We are taking a ride in it tomorrow. I will try a compression check then.

First and foremost, compression check. Technically, it should be done with engine warm, all plugs out, and at WOT position, but, as you may know, those conditions aside, the most important criteria is that all cylinders are within 10 pounds or so of each other. SHould be in the 100-120 psi range. If one cylinder is more than 10 apart from the others, or less than 90 lbs or so, walk away.

The four-cylinder 115 HP mercs of that vintage (I don't know if they make e'm the same nowadays, I was a tech several years ago) had some funky carb design whereby at idle, they ran on just 2 carbs, and as you increase throttle, the other two kick in. This was sold by Merc as a fuel saver, for efficiency at idle. I personally never liked the system, as they were always a bit rough at idle, but more frequently had hiccups in the transition as power was applied. Not necesserily junk, but not necessarily Merc's best system ever, either.

The gear lube, as you know, is the other main criteria. Just pull the drain plug quick, and check for either water, milk, or excessive metal shavings (there should be a few shavings, this is normal).

Other than that, just make sure it's not corroded to hell (I don't know if you're on fresh water or not).

Good Luck.

Take the cover off and look:D Check the lower unit oil, maybe drop the lower gear case, Plugs, Comp check, and maybe pull a/the head to look for trouble. They are pretty indistructable so that is it. Take it out and run it wide open for an hour.:crazy:

We have an 89 Merc 115 on our 17' ski boat. Like riskybusiness says, they are not the best idling engine because of the carb setup. Off idle it is a good little motor for skiing and running around, just the usual maintenance. I had the engine tuned and idle set (with feeler gauges I think) by an excellent Merc outboard guy and he said to never touch it, so I haven't.
Make sure the trim and gauges all work, that can be a sign of bigger electrical problems.
One hundred and fifty hours is a couple of good seasons of water skiing for us. Don't believe that is all any 10 year old outboard has on it unless it's documented. That said, those engines will just keep running and running with good gas and oil in them.

I was going to comment but Riskybusiness said all I would have said.

Thanks for the great detailed answers! I am going for a ride tomorrow. It's good to know the specifics on how it operates.