what to use to clean piston heads and cylinder walls

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chiefcatchemall

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Well I am going to rip my powerhead off and take a look at the piston heads and cylinder walls to take a look and see if the cylinders are scored at all. My question is when Im there what should I use to manually decarb the piston heads and what it is I should use to clean the cyl walls?...When I am finished cleaning it shouldnt I put a few drops of my 2 stoke outboard oil in and coat the walls and piston heads? I know I obviously dont want to use anything that will scratch up the cylinder walls, but I was just curious as to what you guys use or what works best to get clean?
 
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robert graham

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Re: what to use to clean piston heads and cylinder walls

You probably/hopefully won't need to clean the cylinder walls, but some fine steel wool would polish them up, if required. The crowns of the pistons and cylinder ports is where most of the carbon usually is found...I use scrapers, putty knives, steel wool, 3M scrubbing pads, carb cleaner, most anything just as long as I don't put heavy scratches on the aluminum surfaces. Some oil on the cylinders is always a good idea. Good Luck!:)
 
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chiefcatchemall

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Re: what to use to clean piston heads and cylinder walls

Yup, this is just what I did on my other outboard on monday. Did just what you said. Seemed to really make a difference on my '69 sportwin 9.5!!! Just wanted to make sure I wasnt going to do any harm! Thank you
 
Silvertip

Silvertip

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Re: what to use to clean piston heads and cylinder walls

Why are you removing the power head to do this. Remove the head and everything is looking at you. If you see scoring, THEN remove the power head as a rebuild is necessary. Hard wood or plastic scrapers will work to remove carbon. Avoid metal scrapers as they can dig into the piston crown (aluminum) and create hot spots.
 
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chiefcatchemall

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Re: what to use to clean piston heads and cylinder walls

Silvertip said:
Why are you removing the power head to do this. Remove the head and everything is looking at you. If you see scoring, THEN remove the power head as a rebuild is necessary. Hard wood or plastic scrapers will work to remove carbon. Avoid metal scrapers as they can dig into the piston crown (aluminum) and create hot spots.
Click to expand...

Excuse me, sorry about the confusion. I meant head, not powerhead. Well it wasnt pretty in there...TONS of carbon on piston crown. And I noticed one of the lower bolts was soaked in oil as I was taking it out...I do not think that the head has ever been removed before...What would cause all of this build up? Its nasty in there...Ill post some pics later on when I get on my other computer..Dont appear to be any grooves in the cyls though...
 
HighTrim

HighTrim

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Re: what to use to clean piston heads and cylinder walls

Use OMC Engine Tuner from the dealer, it works wonders, or Seafoam. Both are made to remove carbon buildup.

From now on, do a decarb annually to clean the powerhead, and run Seafoam or BRP Carbon Guard in your fuel system to keep the buildup minimal if any at all. There are some on here that say that Seafoam or Engine Tuner are snake oils, I firmly believe they are not.

While the head is off, check it to ensure it is true and square. I put a piece of emory paper on a piece of glass and do figure 8s with the head. Also be sure to torque the head bolts to spec, and torque in proper sequence. That is important.
 
Faztbullet

Faztbullet

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Re: what to use to clean piston heads and cylinder walls

Avoid metal scrapers as they can dig into the piston crown (aluminum) and create hot spots.
Click to expand...
Only if a bit of the scraper breaks off........ a ding,dent or groove will not cause a hot spot in crown.
 
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chiefcatchemall

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Re: what to use to clean piston heads and cylinder walls

Well does anybody know what the specs for tightening the head bolts are? Its a 73 johnson seahorse 20 hp..Also the sequence? Never really knew about that. Thanks for the heads up!!
 
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chiefcatchemall

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Re: what to use to clean piston heads and cylinder walls

Here are the pics of what it looks like inside...





...I noticed one of the bottom bolts were covered in oil...thought this was strange?...the only one like this...









attachment-12.jpg



...what is this white build-up on the outside of the cyls?





I wanted to do a decarb without removing the head, but couldnt keep the engine running long enough to do it...My plugs were black after I ran it for about a minute before it died...should a good cleaning take care of this problem guys? Sorry about the poor quality of the pics, my phone isnt the greatest...
 
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dehydrated

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Re: what to use to clean piston heads and cylinder walls

The white stuff in walls is calcium from h2o also charcoal lighter fluid works as a good cleaner .what was your compression on those cylinders before you took it all apart?
 
HighTrim

HighTrim

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Re: what to use to clean piston heads and cylinder walls

Im thinking its 8 to 10 ft/lbs, but dont have a manual for that specific motor in front of me, someone will verify. That is what the older 18hps are anyways.

You start in the center and spiral outwards when torquing. Use half the torque value first, then go around again with the final torque setting. This ensure even torque on the head. The new head gaskets do not require sealer either, put them on dry.
 
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