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Old 04-04-2009, 10:02 PM   #1
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Default Engine piston pitting?

Is the top of the piston supposed to turn a brownish black after its broken in? or is it supposed to stay shiny silver?

Also, what does pitting look like? I heard this happens from to much compression.

thanks
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Old 04-04-2009, 10:06 PM   #2
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Originally Posted by team2zon View Post
Is the top of the piston supposed to turn a brownish black after its broken in? or is it supposed to stay shiny silver?

Also, what does pitting look like? I heard this happens from to much compression.

thanks
That is perfectly normal What do you mean by pitting?
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Old 04-04-2009, 10:13 PM   #3
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Pitting is not normal, carbon colored coating is normal as well.
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Old 04-05-2009, 05:49 AM   #4
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Pitting is little pin holes starting to develop in the piston . This can happen from too much compression , not enough shims or longer glow plug .
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Old 04-05-2009, 06:23 AM   #5
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if the top of the piston looks like its been sandblasted ...its been run to lean....carbon build up is always normal
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Old 04-05-2009, 06:39 AM   #6
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I have heard that running too hot of a plug can also do that.
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Old 04-05-2009, 06:41 AM   #7
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Originally Posted by Dalepad View Post
I have heard that running too hot of a plug can also do that.
I know with regular gas engines a too hot plug will do it . Not sure about with glow plugs .
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Old 04-05-2009, 06:45 AM   #8
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Pitting is like pinging in a 1:1 engine. It's mostly from pre-detonation of the fuel/air mix. This could happen when the engine is overheated, using a hot plug (similar to advancing the timing), running too lean or not shimmed properly.

Another effect of pre-detonation is excessive wear on the conrod and shaft journal bushings.
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Old 04-05-2009, 09:23 AM   #9
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Quote:
Originally Posted by Briguy View Post
Pitting is little pin holes starting to develop in the piston . This can happen from too much compression , not enough shims or longer glow plug .



Pitting is surface deformation on the piston head and underneath the button head. They become sand blasted due to overheating, perhaps due too high percentage on nitro % or running too lean.

I've got this pitting problem 3 times......

To reduce pitting : polish the piston head and button head until they become so shiny. I find this trick work very well to minimize pitting. I use dremel and round wool type tip, especially meant for polishing jewerly.

Don't polish inside the sleeve or inside the engine wall where the sleeve is seated.
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Old 04-05-2009, 10:49 AM   #10
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Quote:
Originally Posted by asw7576 View Post



Pitting is surface deformation on the piston head and underneath the button head. They become sand blasted due to overheating, perhaps due too high percentage on nitro % or running too lean.

I've got this pitting problem 3 times......

To reduce pitting : polish the piston head and button head until they become so shiny. I find this trick work very well to minimize pitting. I use dremel and round wool type tip, especially meant for polishing jewerly.

Don't polish inside the sleeve or inside the engine wall where the sleeve is seated.


He asked what it looks like . Not what it is , what it looks like . So not sure why you are laughing at my post .
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Old 04-05-2009, 12:23 PM   #11
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Quote:
Originally Posted by Briguy View Post


He asked what it looks like . Not what it is , what it looks like . So not sure why you are laughing at my post .
Pitting in this conversation means the surface condition of a piston head :
Look like having a carbon build up is normal.
Look like it has been sand blasted, it's not normal.
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Old 04-05-2009, 01:00 PM   #12
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Ya , I know . Where did I say pitting is normal ?
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Old 04-05-2009, 02:08 PM   #13
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Quote:
Originally Posted by asw7576 View Post



Pitting is surface deformation on the piston head and underneath the button head. They become sand blasted due to overheating, perhaps due too high percentage on nitro % or running too lean.

I've got this pitting problem 3 times......

To reduce pitting : polish the piston head and button head until they become so shiny. I find this trick work very well to minimize pitting. I use dremel and round wool type tip, especially meant for polishing jewerly.

Don't polish inside the sleeve or inside the engine wall where the sleeve is seated.
TY for explaining the pitting term for me
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Old 04-05-2009, 02:12 PM   #14
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Originally Posted by asw7576 View Post



To reduce pitting : polish the piston head and button head until they become so shiny. I find this trick work very well to minimize pitting. I use dremel and round wool type tip, especially meant for polishing jewerly.

Don't polish inside the sleeve or inside the engine wall where the sleeve is seated.
Instead of polishing you should fix the problem why it is happening . That is just putting a band aid on it instead of taking care of it .
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Old 04-05-2009, 02:18 PM   #15
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Quote:
Originally Posted by Briguy View Post
Instead of polishing you should fix the problem why it is happening . That is just putting a band aid on it instead of taking care of it .
wouldn't using a fuel such as 30% heli fuel with more oil would lubricate the piston enough to minimize pitting? Back when I used 20% I would mix castor oil in it
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