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Cylinder bore question

racerone said:
????------" weak spark washing away the oil "------Where did that wild idea come from ?-------Just more proof that oil / lubrication inside a 2 stroke is not well understood !!
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I read that on a boat repair forum. I had never heard of that before and thought it did not make a lot of sense but the poster seemed knowledgeable. I figured it was just one of those "you learn something new everyday" deals...
 
Well statement like " weak spark washing away the oil " just make me chuckle a wee bit.-----Many folks just do not know how oil works in a 2 stroke or what happens when mixed fuel goes through a carburetor.
 
I don't see any thing that would make .022 gouge. The torque specs in your 120/140 service manual are not the same as 110.
 
racerone said:
Well statement like " weak spark washing away the oil " just make me chuckle a wee bit.-----Many folks just do not know how oil works in a 2 stroke or what happens when mixed fuel goes through a carburetor.
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What are you talking about? Oil mixes with fuel and provides lubrication to moving parts. Are you privy to some special knowledge of how oil lubricates at the moleculer level that others don't know about? If so maybe you could share your secret knowledge
I'm still looking for a clue as to why the damage occurred.
 
Sharp eye to spot the 120 / 140 pages on the work bench.----Any more pictures of those 2 pistons and the other 2 pistons.------The color marking on rod was not due to anything inside the running motor.----More piston pictures needed.
 
baddog1016 said:
Is it possible an overheat led to the piston scuffing and then then water pump impeller was replaced prior to unloading the boat?
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That's a good thought but the seller bought a brand new impeller kit but did not install it, it's new in box sitting in the boat.
 
Will do. I'm trying to arrange a phone call with the seller that might provide ml some clues. He just texted he found the ground wire on the VRO was loose but did not elaborate. When he bought the boat a few years ago he was told the motor was rebuilt. It has standard 3.5" bore.
 
Well statement like " weak spark washing away the oil " just make me chuckle a wee bit.-----Many folks just do not know how oil works in a 2 stroke or what happens when mixed fuel goes through a carburetor.​
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That is funny;)...Sort of like the poster that stated Merc Inlines run lean on oil on top cylinder due to gravity. Engines will not run on liquid fuel ..it has to be atomized in a gaseous state.
 
Wires on a VRO are for warning of a " No oil condition "-----I thought those pistons had low hours on them.-----Fact ----Most folks are unaware of how to test a warning horn or do a VRO consumption / output test.-----If a motor start and roars everything must be OK.
 
When he bought the boat a few years ago he was told the motor was rebuilt. It has standard 3.5" bore.​
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Heres the red flags popping up..
1) Was told it was rebuilt
2) Bore is STD
3) pistons look new
I will say that that the cylinder that's damaged , rolled a ring and scored cylinder. Then someone did a backyard refresh(not rebuild) by honing and installing new pistons. Now its had a overheat occurrence and your stuck with it..
 
I agree with Pappy. Perhaps you can find a nice block at Tim's Outboard in Hackensack MN. Typically outboards here in Northern MN are clean and lower hours. Great outlet for used parts. Talk with Mike or Dan 218 682 2331. If your committed to your bore or sleeve job, you will likely spend more money and time.
 
Timguy... thanks for that contact. There are no marine salvage outfits in Sacramento anymore. There is one about an hour south but they don't have a block. I don't want to get one from the Bay Area as most of those are used in saltwater. If my machinist says the block will need a sleeve then I will begin a search nationwide starting with Tim's Outboard.
 
Okay, good. This is a friendly and expertly operated family business for going on 60 years. Those who have shared business with Tim's most often give extremely high praise. I would never steer you wrong. Twin Cities Outboard in Minneapolis/St. Paul is a bigger operation, but not my first choice. Minnesota is the "Land of 10,000 Lakes", our boating season lasts barely 6 months, so we are abundant with quality outboard parts.
 
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Here is piston #1, the only piston with no damage. At 1/4" from bottom of skirt it measures 3.495 parallel to the wrist pin and 3.491 perpendicular to WP.
 

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No way. That wasn't the cause. She got hot and lack of lubrication. Perhaps the same problem surfaced after the backyard overhaul.
 
The #1 cylinder has no damage while 2 and 3 suffered badly.

Do the OMC V4's have uneven manifold distribution or get less coolant where cylinders 2 and 3 run hotter? Interesting that the three pistons got that hot while #1 was pretty much unscathed.

All four spark plugs are dark chocolate brown with no aluminum deposits evident on the electrodes.
 
The #2 is top on port and #3 is bottom on starboard.----@ different thermostat / poppit valves in the picture.-----Were the head gaskets on correctly , yes , no , not sure ?
 
racerone said:
The #2 is top on port and #3 is bottom on starboard.----@ different thermostat / poppit valves in the picture.-----Were the head gaskets on correctly , yes , no , not sure ?
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The gasket is still stuck to the port side cylinder head, picture attached. Keep in mind that will I have built and rebuilt many types of engines, both 2 and 4 stroke with good results but I have no previous experience with outboards.

The factory manual says "install head gasket per instructions on gasket" but does not offer any pictures. In the attached picture you will see the port head gasket says "Cover" with a directional arrow. If the arrow should be pointing towards the engine cover then the gasket is mounted incorrectly and I can see how coolant flow would be affected. The gasket on the starboard side is off and I did not notice how it was installed but if the port side gasket is wrong there is a pretty good chance the starboard side is wrong too.

What's the verdict...is the gasket on the wrong way and if so would it have likely caused the problem?
 

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