Mercury 80hp

[tworotorturbo]

One of my neighbors passed away and I was given a cool old boat. It was apparently repowered with a Mercury 80HP, used a few times then it sat on the trailer for over 10 years. I hooked up a battery and the power trim works...trim sounds smoother than my 2014 Honda 90.

The motor was covered so it looks new. Just dusty but no rust or corrosion. What are the chances this can turn out to be a good running motor? I will do a compression check soon. Anything special I should do before trying to crank it over?

[spartacus]

If the motor has been stored and there's no way of determining when it was last used, I'd change the impeller as a matter of course. Renew the gear oil too. When the gear oil comes out you'll have an indication of any water ingress, so renew the fill and drain hole fibre washers.

1/ Put the battery on charge, check levels if it's serviceable and top-up with distilled water
2/ Grease all nipple points, including throttle and gear linkages under the cowl
3/ Remove old spark plugs, squirt a little 2-stroke oil straight into cylinders, fit new sparks
4/ Fresh fuel, including any fuel that's in the engine fuel filter
5/ Drain carbs (should be a cross-head bolt on each carb fuel bowl)
6/ Grease the butterfly choke mechanism behind the air-box
7/ Not sure if this is an auto-oil injection or not? Check levels or mix up new fuel supply say 4-5 litres at least 50:1. It'll smoke, but better safe than sorry

[Phil M]

It looks like a 3 cylinder clamshell (clip on front of engine and cowl opens on hinges at the rear). If so they are good engines and are oil injection (tank on front left of engine and level gauge/viewing slot on stbd side). Being paranoid I'd run it on pre-mix fuel to start and introduce a bubble into the oil lines from tank to pump. Tehn when it runs, you can watch the bubble and if it moves away from the tank, the pump works. Watch the oil hoses though. Mine disintegrated when I looked at them and left a large puddle of oil on the workshop floor.

Phil M

[tworotorturbo]

Thanks for the tips guys. I towed the boat home today and finally got a chance to peek inside the cowl. I will follow those steps and report back!

[spartacus]

What's in the oil reservoir tank? It looks like screen-wash!

Looks tidy though. At some point you may want to check the condition of thermostat (on block where spark plugs are). If you remove round cover plate then you'll need a replacement gasket.

[tworotorturbo]

Phil you were right about the oil hoses! I poured a quart of oil into the reservoir and then noticed the leaking hoses. It had a small crack and when I barely touched it the whole hose fell apart. New hoses on the way

I got around the getting a new key and finally cranked it over. After about 10 seconds if cranking she fired right up. I ran it on muffs and also in a tank but no pee, I'm guessing the impeller is disintegrated from being over ten years old.

Compression is 140 psi on all three. Thats on a cold engine that was only ran for less than a min for the first time in ten years. I will toss this thing on my Zodiac and see how it does on the water.