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Posts: 81
Location: Van Buren, Indiana | Looking at a boat w/ this motor. If well maintained is this good? Or might you be looking at a rebuild? I know if compression is good that is a good sign, but is this close to a normal rebuid?
Thanks In Advance for any Info!! |
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| Those engines are designed to run thousands of hours not hundreds. Check the compression and you should be good. Make sure you check compression when engine is warm, all plugs out, throttle plate wide open. kill switch off. |
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Posts: 202
Location: Angola, IN | If you end up owning any 2-stroke outboard, one important thing to do is de-carbonize the pistons. It's often neglected and not done. Carbon deposits on pistons is the #1 cause of failure/breakage/damage in an outboard engine.
It's easy to do. You can just do it in the spring when you install new plugs.
One easy way to do this is to mix up a gallon of fuel with a whole full pint of Seafoam and run 1/3 of the gallon through the motor and get it hot in your driveway and at idle. Turn off for 15 minutes. Do this cycle three times until gas is gone. (Of course, have ear muffs on your lower unit....just sayin')
PEA (polyethylene amine) is about the only known good carbon/deposit cleaner that actually works in gas at reasonable concentrations. One of the most readily available and high concentration of PEA is Gumout Regane High Mileage gas treatment. Available at Walmart, auto part stores, Meijer, etc for around $5-$6 a bottle. Mix a bottle to every 10-15 gallons of gas in your tank every 3 or so tank of fuel. So, if you fill up empty, and you hold 40 gallons, dump in 3 bottles of this Gumout Regane. This will prevent any new deposits from forming.
I know what I'm talking about. I'm a chemist. I spend a lot of time researching and reading about oils, engines, etc. |
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Posts: 425
Location: Roseau | Steve, how about 4 strokes?
Thanks |
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Posts: 81
Location: Van Buren, Indiana | Thanks for the info Steve, I may have to wait on the boat with the 250, but my current boat has a 1990 70hp Evinrude that will benefit from that cleaning. The 1 gal of gas is a good idea this motor does not have the single port like my '05 Johnson 150 on my '04 Lowe Stinger did, for decarbonizing. |
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Posts: 202
Location: Angola, IN | Fisher: I don't think decarbonizing a 4-stroke is as important. But all combustion engine have a tendency to develop deposits in the combustion chamber. For a 4-stroke, I'd simply a bottle of Gumout Regane High Mileage or Techron Concentrate (both contain high amounts of PEA) for every 10 gallons of fuel in your tank every other or every 3rd tank to keep everything nice and clean.
It's real easy to get the wrong stuff, because these companies make so many products. And only a few contain any PEA. Here are the two I recommended above:
http://www.gumout.com/ourProducts/highMileageFSC.asp
http://www.techron.com/techron-concentrate-plus/Default.aspx
PEA is the only deposit cleaner that removes deposits without leaving any residue behind. It's the best stuff. Another product by Red Line, is called SI-1 and it also contains a massive dose of PEA.
http://www.redlineoil.com/product.aspx?product=60103
If you google "decarb outboard" you will find several methods of doing this.
Another way is to remove spark plugs and liberally spray Seafoam into the cylinders (they make aerosol cans of Seafoam now). Let it sit over night. And then add some to your fuel and burn out the carbon. You can actually use water to clean out carbon deposits as well. Never did it to an outboard yet, but if you've ever torn apart an engine after a head gasket failure, you'll see how clean those piston tops come with a little steam. I de-carbed my old Chevy truck one with water. Slowly poured 2 gallons of water down the intake (took me about 20 minutes) and my entire neighborhood had a thick white fog rolling through it!!! And it smelled just like a burnt firecracker!! 100% carbon being blown out the exhaust pipe. It got rid of my ping/pre-detonation immediately. But use this method at your own risk!! You could hydrolock your engine if you aren't careful.
One thing you'll notice when de-carbing a 2-stoke is, your idle and cold starts will be so much better. I have a 44 year old 115HP Johnson that use to never run at idle and took forever to get started when cold. Not any more.
The carbon closes up the transfer ports found in 2-strokes and prevents reed valves from opening and closing properly. It also freezes up rings by embedding in the ring lands on the pistons.
Edited by SteveHulbert 2/21/2013 2:07 PM
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2006 Opitmax 250 Racing 300hrs?