Bad Head Gasket?

supradjza80

Mr. Formula SAE
Apr 24, 2007
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Appleton, WI
www.uwracing.com
No, I do not have any way to log AIT's. The setup on the intake side is an Apexi intake to a stock CT26 @ 15 psi, and hard pipes to the stock IC. Obviously the cooling fan does get hot air on the air filter when sitting still but I didn't think this had much effect at speed.

IJ, Just because I am such a newb at engine internals, would you expect damage like this to require a bore and hone of the block (and new pistons) or just a hone job? Remember I am not looking to make a monster out of this car, but I do want to fix ANY problems with it which is why stock pistons and bore are A ok with me. Also so I make sure I understand your ring gap sizing you are saying on the top ring 4 thou per inch of bore size, so 4 thou * 83 mm/25.4? And for the second ring you use 5 thou per inch? And you add 4 thou to each if the engine is ran hard? Do you do anything different to the oil ring?
 

IJ.

Grumpy Old Man
Mar 30, 2005
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I think in your application the stock IC just isn't going to cut it and is heat soaking badly :(

Personally I'd Bore and Hone and go the next up piston size.

83mm = 3.267" x 4 thou = 13 thou then add 4 for 17 thou top gap (don't forget to add in the new oversize bore)

83mm = 3.267" x 5 thou = 16 thou then add 4 for 20 thou 2nd gap

I don't do anything for the Oil rings at all as they're not exposed to combustion heat directly so as long as they're not gapless they're fine.
 

supradjza80

Mr. Formula SAE
Apr 24, 2007
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Well, the Engine is out and the pistons are pulled. Pics can be seen here http://s327.photobucket.com/albums/k463/supradjza80/Supra Engine Build/

I am actually thinking it was not the rings that caused this, they all look to be perfect and show none of the wear I would expect for this type of damage. The pistons however show pretty good scoring on the skirts.

#6 Skirt area, heavily scored, worse then the block
p1583257_1.jpg


Rod Bearing - they all looked about like this which I thought looked quite good, Crank also looks perfect still
p1583257_2.jpg


p1583257_3.jpg


Picture of some debris in the bottom of the pan, items are kinda big and to me look like Head Casting Flash - Is this Normal? Its the only place I could think of the material coming from. Oil that came out of it was clean - not metallic sparkles.

sm_photo_missing.jpg


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p1583257_4.jpg
 

IJ.

Grumpy Old Man
Mar 30, 2005
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The Rings nip up and scour ALL lube from the cylinder wall and make a localised hot spot then the piston galls and tries to weld itself to the bore but can't so you get the uglies :(