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-   -   Scratched pistons (https://honda-tech.com/forums/engine-machining-assembly-164/scratched-pistons-3321720/)

Cho0se 06-08-2018 07:38 AM

Scratched pistons
 
https://cimg4.ibsrv.net/gimg/honda-t...1358a41bc.jpeg
https://cimg5.ibsrv.net/gimg/honda-t...684ca7226.jpeg
https://cimg6.ibsrv.net/gimg/honda-t...a3b75b1d5.jpeg
Hi, I have a big problem. My engine runs very well, buy oil consumtion was very high, so i disassembled my Honda H22 engine after 2000km run.

Engine has dry darton sleeves and CP pistons.

3 pistons are scratched :-(

How can it happen? Very rich fuel mixture? Overheated?

Is is repairable?

Thank you very much!

Aradin 06-08-2018 12:50 PM

Re: Scratched pistons
 
What was your piston-to-wall clearance? What side of the piston are these scratches on? Intake or exhaust? Both? Was the engine assembled by a shop? Was this a turbo engine? At first glance it looks like your piston-to-wall clearance was just a hair on the tight side and the engine got a good amount of heat in it at one point like during a long 5th gear pull, etc.

As far as being repairable it depends. If money is an issue and the scratches aren't too deep, you COULD sand & polish the skirts. I'm not saying you should but you could. The pistons will run small in certain spots and if there's any issues with the cylinders you'll be right back to where you are now. Best to fix it the right way and start over with a new set in some freshly machined cylinders.

Cho0se 06-08-2018 11:42 PM

Re: Scratched pistons
 
P2W clearance was from CP piston specification. Scratches are only on pistons 1,2 and 4 and only on exhaust side. Engine was assembled by shop. Can it happen by very rich mixture?

1HGEJ2 06-09-2018 01:11 AM

Re: Scratched pistons
 
what is very rich mixture? do u have a wideband? looks like a bad p2w clearence for me.

Cho0se 06-09-2018 02:11 AM

Re: Scratched pistons
 
Yes i have. 12-13 whole map.

1HGEJ2 06-09-2018 10:24 AM

Re: Scratched pistons
 
12-13 is not Rich enough to make this scratches...8-10afr on long Time maybe...this scratches are Mechanical problem.

NVturbo 06-13-2018 02:45 AM

Re: Scratched pistons
 

Originally Posted by 1HGEJ2 (Post 51655257)
what is very rich mixture? do u have a wideband? looks like a bad p2w clearence for me.

More like half-ass install job by idiots at the shop. OP, I would refrain from going back there.

Creator 06-13-2018 12:44 PM

Re: Scratched pistons
 
Not sure if you played with the rings at all when you took your pistons out but, in your top picture all of the end of the oil rings are all on top of each other. This is also a sign someone doesn't know what they're doing.

Cho0se 06-22-2018 02:04 AM

Re: Scratched pistons
 
Thank you guys!

P2W clearance was tight. Clearance was 0,046mm. Specification sheet says 0,0762 mm.

Is it that problem?

Thank you.



Josef

B and B 06-22-2018 08:06 AM

Re: Scratched pistons
 
Yes

sleepencivic 07-05-2018 05:22 AM

Re: Scratched pistons
 

Originally Posted by Cho0se (Post 51655249)
P2W clearance was from CP piston specification. Scratches are only on pistons 1,2 and 4 and only on exhaust side. Engine was assembled by shop. Can it happen by very rich mixture?


there specs are to tight for my liking and most engine builders in the honda world! dont go tighter than .0035-.0040 on a turbo motor I dont care what the spec sheet says for under 500 hp

1HGEJ2 07-05-2018 10:08 AM

Re: Scratched pistons
 
0.0040 is the best way for cp, je, wiseco and arias

1HGEJ2 07-05-2018 10:09 AM

Re: Scratched pistons
 

Originally Posted by Cho0se (Post 51666024)
Thank you guys!

P2W clearance was tight. Clearance was 0,046mm. Specification sheet says 0,0762 mm.

Is it that problem?

Thank you.



Josef

thats to tight!!!! 0.04mm is for oem cast pistons.


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