Bluish cylinders

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Matt80
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Bluish cylinders

Post by Matt80 » Wed Jul 19, 2017 6:01 am

Hi, I just received these pics from a friend with a turbo Nissan engine and was curious to understand what is happening here.
Leak test was ok, around 11% in all the cylinders, but something is definitely not ok, as pistons and chambers are equally black and cylinders are scratched and dark blue :shock:
Is that bore wash and overheat?
PS: it has water injection and 6000 miles

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joe 90
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Re: Bluish cylinders

Post by joe 90 » Wed Jul 19, 2017 6:39 am

Looks like it got too hot.

More details needed.......boost, power etc.


Stock pistons?
Piston skirts?
How much knock?
What fuel?


If the water injection was working properly, there wouldn't be all that carbon / oil deposits.

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Re: Bluish cylinders

Post by mag2555 » Wed Jul 19, 2017 7:35 am

Looks like the Pistons are getting knocked Round and the rings are unseating .

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Re: Bluish cylinders

Post by modok » Wed Jul 19, 2017 9:21 pm

Looks odd, but i don't think the color it means anything in particular.
Your burn weird fuels, it makes weird deposits. Every color of the rainbow is possible

The bores being scored might mean something.
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Re: Bluish cylinders

Post by Matt80 » Thu Jul 20, 2017 11:41 am

Unfortunately I just know it runs on pump gas, no knock in ecu logs and that ptb is 0.0035" (3.386" bore)

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Re: Bluish cylinders

Post by DCal » Thu Jul 20, 2017 1:23 pm

Were the pistons shotpeened or otherwise blasted because it looks to me as though the scratches go the full length of the piston travel as if there is foreign particles imbedded in the skirts. The ring belt part of the bore at the top doesn't all that bad but I would bet that he's not getting 11% at mid stroke with those scratches.

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Re: Bluish cylinders

Post by Keith Morganstein » Thu Jul 20, 2017 4:12 pm

Yep, those scratches are consistent with dirt contamination. Could be ingested (air intake) could be debris when assembled.

Note: overheating will cause scuffing on four corners of the pistons and leave marks there on the cyl walls.
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Re: Bluish cylinders

Post by hoodeng » Thu Jul 20, 2017 10:56 pm

Scratches originating above the ring pack line and continuing down the bore is air filtration contamination ,scratching or scoring below the oil ring line is oil contamination,the pictures show both but the scoring below the ring line is a lot worse than above ,the blueing of the bores in the product i work on is definitely over heating . The carbon on the valve relief side of the piston crown is oil washed . I take it the major thrust face is opposite the valve relief side of the piston?
Strip and inspect looks to be the next step, cheapest way out.

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Re: Bluish cylinders

Post by modok » Fri Jul 21, 2017 4:50 am

Matt80 wrote:Unfortunately I just know it runs on pump gas, no knock in ecu logs and that ptb is 0.0035" (3.386" bore)
Some pump gas has blue dye, oil can have dye, and windshield washer fluid has blue dye.

The guys might be correct that the scratches are from some kind of dirt contamination. Happens a lot.
We all know engines need to be "clean", but It's no simple matter to master that.
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Re: Bluish cylinders

Post by Matt80 » Mon Jul 24, 2017 7:47 am

hoodeng wrote:Scratches originating above the ring pack line and continuing down the bore is air filtration contamination ,scratching or scoring below the oil ring line is oil contamination,the pictures show both but the scoring below the ring line is a lot worse than above ,the blueing of the bores in the product i work on is definitely over heating . The carbon on the valve relief side of the piston crown is oil washed . I take it the major thrust face is opposite the valve relief side of the piston?
Strip and inspect looks to be the next step, cheapest way out.

Yes thanks, I'll strip and inspect asap. But I also need to start a new thread about bore wear

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Re: Bluish cylinders

Post by Matt80 » Mon Jul 24, 2017 8:59 am

About the dirt under the oil rings, he has an Accusump. Always worried for any dirt there.
Is there any filter for it?

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Re: Bluish cylinders

Post by Matt80 » Thu Jul 27, 2017 4:06 am

Other pics:
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Re: Bluish cylinders

Post by Matt80 » Sun Sep 03, 2017 2:33 pm

I finally received the block in my hands: what do you think of these scratches?

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Re: Bluish cylinders

Post by Tuner » Sun Sep 03, 2017 2:46 pm

Picture looks like the top of that piston has seen some detonation. Is it a trick of the light and camera, or does it look like it has been sandblasted? Detonation looks a lot like cavitation burn on a propeller.

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Re: Bluish cylinders

Post by exhaustgases » Sun Sep 03, 2017 2:57 pm

Abrasive ingestion isn't picky about what side it likes the most. A compromised oil film can be.

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