gook under pistons

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User1

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<TABLE cellSpacing=1 cellPadding=6 width="100%" border=0><TBODY><TR><TD colSpan=2><TABLE width="100%" border=0><TBODY><TR><TD style="PADDING-TOP: 4px" vAlign=top colSpan=2>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]gook under pistons<!-- google_ad_section_end -->

[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial]September 2 2000 at 5:20 PM[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "b";n54_em = n54_em + "o";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "c";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "o";n54_em = n54_em + "t";n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "i";n54_em = n54_em + "l";n54_em = n54_em + ".";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "m"; document.write("bob"); // --> </SCRIPT>bob <NOSCRIPT></NOSCRIPT> [/FONT]</TD></TR><TR><TD vAlign=bottom colSpan=3><HR></TD></TR><TR><TD colSpan=3>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->cleaning up the pistons,,there was burnt oil (caked carbon) attached to the underside of the piston top, 1/4" in a few places,,I have never seen this before. Any one have an idea as to how to prevent a re-occurance,,thought maybe it was cheap oil or that the motor just got realllllly hot. Bottom line, I dont want it again,,,any thoughts?
Also, the piston is 1 or maybe 1.25 mm narrower at the top than at the bottom. Is that time to get new pistons?
Now Mac dont get excited but this is a Gm 2.5 4 cyl out of the camaro, I know it doesnt fit here, but I thought maybe someone else might profit from my learning something new<!-- google_ad_section_end -->

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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]Author[/FONT]</TD><TD>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]Reply[/FONT]</TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]Mac[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I don't mind!<!-- google_ad_section_end -->

[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]September 2 2000, 9:18 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Talk about whatever engine you've got cracked open! Of course we all can learn from things like that
happy.gif


I wish I could help, but I don't know what the gunk might be aside from years of burnt-on-broken-down oils, or perhaps someone over time has plugged this engine full of some parts-store-additives like no-smoke & stop-leak etc? That could gunk up the internals... otherwise, ??

-Mac.<!-- google_ad_section_end -->

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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "j";n54_em = n54_em + "i";n54_em = n54_em + "m";n54_em = n54_em + "b";n54_em = n54_em + "r";n54_em = n54_em + "o";n54_em = n54_em + "1";n54_em = n54_em + "0";n54_em = n54_em + "0";n54_em = n54_em + "0";n54_em = n54_em + "@";n54_em = n54_em + "t";n54_em = n54_em + "h";n54_em = n54_em + "e";n54_em = n54_em + "-";n54_em = n54_em + "l";n54_em = n54_em + "a";n54_em = n54_em + "i";n54_em = n54_em + "r";n54_em = n54_em + ".";n54_em = n54_em + "d";n54_em = n54_em + "e";n54_em = n54_em + "m";n54_em = n54_em + "o";n54_em = n54_em + "n";n54_em = n54_em + ".";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + ".";n54_em = n54_em + "u";n54_em = n54_em + "k"; document.write("Julian"); // --> </SCRIPT>Julian <NOSCRIPT></NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 30px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Cooked<!-- google_ad_section_end -->

[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]September 4 2000, 5:58 AM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 30px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->It could have been caused by prolonged running with a lean mixture. The pistons can get a tad on the hot side in these conditions - and this probably ties in with an oil additive used to keep the thing running in those conditions.

The cone shaped pistons is probably an attempt to maintain the correct tolerances when the engine is fully warmed up. The top of the piston in some engines is designed to expand more than the lower part of the piston (around the gunion - or however you spell it) as the top of the piston gets much hotter than the lower part (simple thermodynamics). As a point of interest do the crank pathways incorporate some oil-cooler jets aimed at the back of the piston?<!-- google_ad_section_end -->

[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]Doc[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 45px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->another possibility?<!-- google_ad_section_end -->

[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]September 4 2000, 5:56 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 45px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Not one that I learned from my X, but I had the head off of my model T last week - same deal, also the same material found in the valve compartment. The fellas at the model T forum (www.mtfca.com) tell me that it is common for old oil to crystallize under heat. IE: Thickened oil will burn off its lubricant when heated, moreso when dirty, and will leave this crystaline but greasy residue that is HARD! I chipped away at it with a small chisle and a lead hammer. Sucked up the residue with a piece of fuel line duct taped to my shop vac.

Sound like the same thing you have?

Doc <!-- google_ad_section_end -->

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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "b";n54_em = n54_em + "o";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "c";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "o";n54_em = n54_em + "t";n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "i";n54_em = n54_em + "l";n54_em = n54_em + ".";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "m"; document.write("bob"); // --> </SCRIPT>bob <NOSCRIPT></NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 60px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->yep, same thing Doc, thanks (nt)<!-- google_ad_section_end -->

[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]September 8 2000, 9:01 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 60px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->no text---like I said!<!-- google_ad_section_end -->

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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "b";n54_em = n54_em + "o";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "c";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "o";n54_em = n54_em + "t";n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "i";n54_em = n54_em + "l";n54_em = n54_em + ".";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "m"; document.write("bob"); // --> </SCRIPT>bob <NOSCRIPT></NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 45px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I have heard of those<!-- google_ad_section_end -->

[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]September 8 2000, 9:10 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 45px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->oil cooler jets,,but I have never seen any,,so no, I dont think there are jets in this motor. The diagrams I have seen have tubing to aim the jet.
By the way, Julian, I wanted to again say thank you for pointing me to this site,,that was about 9 months ago. This site has literally saved my life. Thank You!<!-- google_ad_section_end -->

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