Join Date: Oct 2008
Location: South Coast Ontario
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Re: Yanmar in a 25'Tall rig
A Yanmar 1GM may be one of the simplest, most efficient small engines on the planet.
here's what i would do:
1. beg or borrow a manual, or service manual if you can get it.
1a. Pull the dipstick and the oil fill cap. Look for signs of moisture. if there is no caramel or rust on the dipstick or cap, you might be in luck.
2. Flip up the compression lever.
3. if the boat is in the water, make sure the raw water intake seacock is closed.
4. AFTER ENSURING THE TRANSMISSION IS IN NEUTRAL: if the crank handle is with the boat, use the crank handle to try toturn the engine over. If no crank handle, use a 1/2" ratchet and the appropriate size socket (it's gonna be metric). It should turn over without much effort. If it doesn't turn over easily with the decomp lever flipped, STOP. Don't simply grab a bigger wrench or a breaker bar.
5. Pull off the valve cover ("bonnet" in yanmar speak), and if you're able to turn it over, check and set the valve clearance. if it doesn't turn over, unbolt the head.
6. if you have to pull the head to see why it won't turn, take off the alternator, the exhaust elbow, unbolt the fuel hardlines. Now you can pull off the head. of course, you already know this because you followed step1. While you're at it, eliminate the possibility of a stuck starter by pulling the starter assembly. now the motor has no excuse other than sheer oxidatious obstinance not to turn circles like a jack russell in a butcher shop.
7. THIS is the moment of truth. look down the bore, look at the top of the piston, look at the valves, look at the combustion chamber. Carbon is to be expected, rust is not.
8. Fill the cylinder with kroil, brake fluid, or, PB Blaster.
9. Walk away. Let the lubricants do their work, at least overnight.
10. With the cylinder head off, try to turn the engine over. (It is still in neutral, right? if the boat is on the hard, you turned the prop and the shaft turned easily, right? if the boat is in the water you got behind the negine and turned the shaft, right?)
12. Acquire a 2-5 lb. sledge and a chunk of hardwood to use as a drift, and place your hardwood on the piston and smartly strike with your sledge. repeatedly.
oh, and that part about installing an air-cooled engine? I am an old-school VW guy. i know aircooleds, I love aircooleds, and i wouldn't even think of pulling a yanmar and installing an aircooled motor in an enclosed engine room in a small cabin. See all the professional lawntractor pilots wearing earmuffs when mowing?
Imagine that sound contained in a fiberglass hull. For hours on end. and don't even get me started on the heat.
It's 5 o'clock somewhere:
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