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Old 10-12-2020, 04:59 PM   #1
JSR84
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Default Piston wear

I recently pulled my motor as I decided to go with a different setup. When I pulled the heads off I notice that there was significant scoring of the cylinder walls. I decided to pull the pistons and notice that the skirts had excessive wear on them as well, with the side that faces up having worse wear than the underside. My engine always had slightly higher than normal iron and aluminum in oil analysis reports, but nothing crazy. I'm very curious to figure out what caused this. It was a street engine that was started every day and was never run at a track, it never put out more that 450 crank HP.
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Old 10-12-2020, 05:02 PM   #2
JSR84
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Old 10-12-2020, 06:57 PM   #3
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Any pics of the bore(s)?

What was your piston-to-wall clearance?

What alloy are the pistons?
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Old 10-12-2020, 07:17 PM   #4
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those look like Manley platinum pistons, which are 2618 forged.

Those look like my Manleys after ~29k miles with horrible piston slap.

Whats your ptw clearance?
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Old 10-12-2020, 10:16 PM   #5
JSR84
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I'll grab some pictures of the bore. The engine only had 12,000km on it, the PTW clearance was .0025 according to the build sheet, I haven't actually confirmed that for myself. The pistons are Manley Platinum's 2618.

The piston slap was audible when cold, and very tame when warm, you could hear it a bit below 2500rpm, but it's was very mild.

Last edited by JSR84; 10-12-2020 at 11:54 PM.
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Old 10-12-2020, 11:56 PM   #6
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Old 10-13-2020, 08:55 AM   #7
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can you feel those scores with your nail?
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Old 10-13-2020, 10:30 AM   #8
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FWIW, I have those same pistons with .0035 PTWC and my motor is incredibly quiet.

Based on that wear, it seems like an oiling issue and/or foreign material in the motor. Do you always let the motor warm up to operating temperature before driving? That could come into play too, given the expansion properties of the 2618 alloy.

During my first motor build ever, I saw the same kind of damage on my CP pistons. I discovered that one of the oil pickup tube bolts worked its way loose due to vibrations, even when torqued to spec
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Old 10-13-2020, 10:46 AM   #9
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Quote:
Originally Posted by rtv900 View Post
can you feel those scores with your nail?
Yeup, the block needs some work for sure.
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Old 10-13-2020, 10:50 AM   #10
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Quote:
Originally Posted by BeastianSTI View Post
FWIW, I have those same pistons with .0035 PTWC and my motor is incredibly quiet.

Based on that wear, it seems like an oiling issue and/or foreign material in the motor. Do you always let the motor warm up to operating temperature before driving? That could come into play too, given the expansion properties of the 2618 alloy.

During my first motor build ever, I saw the same kind of damage on my CP pistons. I discovered that one of the oil pickup tube bolts worked its way loose due to vibrations, even when torqued to spec
Yeah, I was always pretty good about letting it warm up, I even had an oil warmer for the colder mornings, not that it gets that cold around here. It always seemed to have good oil pressure. I was pretty meticulous when I put it together, but that's not outside the realm of possibilities.

Last edited by JSR84; 10-13-2020 at 11:04 AM.
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Old 10-13-2020, 10:56 AM   #11
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Quote:
Originally Posted by JSR84 View Post
Yeah, I was always pretty good about letting it warm up, I even had an oil warmer for the colder mornings, not that it gets that cold around here. It always seemed to have good oil pressure. I was pretty meticulous when I put it together, but that's not outside the realm of possibilities.
Since the compression rings move around some 45 degrees (not 100% on the exact amount)...

Did you happen to deburr the compression rings? I'm thinking that could have lead to scoring on the cylinder wall, with greater emphasis on one side.

I'd think you'd either have burrs on the rings or FM during the initial assembly.
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Old 10-13-2020, 11:06 AM   #12
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Originally Posted by BeastianSTI View Post
Since the compression rings move around some 45 degrees (not 100% on the exact amount)...

Did you happen to deburr the compression rings? I'm thinking that could have lead to scoring on the cylinder wall, with greater emphasis on one side.

I'd think you'd either have burrs on the rings or FM during the initial assembly.
I didn't assemble the rotating assembly, just the long block. Sorry, I should have clarified that. It was an "OTS" block from a reputable builder.
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Old 10-13-2020, 11:30 AM   #13
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Quote:
Originally Posted by JSR84 View Post
I didn't assemble the rotating assembly, just the long block. Sorry, I should have clarified that. It was an "OTS" block from a reputable builder.
Ahhh ok, thanks for clarifying!

I had an issue a long time ago where I trusted the machine shop to thoroughly clean the heads for me, but right when I started the motor up it started knocking like crazy.

Did you remove all the oil passage plugs in the heads and clean the heads inside and out before assembly? I guess there are a lot of different ways FM could end up in the block.

Did you have an engine failure before this one, and did you reuse anything from that build?
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Old 10-13-2020, 12:04 PM   #14
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Ahhh ok, thanks for clarifying!

I had an issue a long time ago where I trusted the machine shop to thoroughly clean the heads for me, but right when I started the motor up it started knocking like crazy.

Did you remove all the oil passage plugs in the heads and clean the heads inside and out before assembly? I guess there are a lot of different ways FM could end up in the block.

Did you have an engine failure before this one, and did you reuse anything from that build?
The previous engine had ringland failure, but there didn't appear to be any contamination in the oil from it. I even cut open the filter to make sure. The heads were refurbished by a shop that came highly recommended. In addition to the heads, they resurface my flywheel, and managed to machine a profile into it which destroyed my new clutch within 5000km. So I wouldn't be surprised if they managed to **** the heads up as well. I have since switched machine shops. And no, I didn't pull the oil plugs, I asked if any further cleaning was required and they said no. That's a mistake that I don't intend to repeat. I have a new set of heads I'm using on this new engine and I've been going at them for hours making sure they're clean as can be.
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Old 10-13-2020, 12:23 PM   #15
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Quote:
Originally Posted by JSR84 View Post
The previous engine had ringland failure, but there didn't appear to be any contamination in the oil from it. I even cut open the filter to make sure. The heads were refurbished by a shop that came highly recommended. In addition to the heads, they resurface my flywheel, and managed to machine a profile into it which destroyed my new clutch within 5000km. So I wouldn't be surprised if they managed to **** the heads up as well. I have since switched machine shops. And no, I didn't pull the oil plugs, I asked if any further cleaning was required and they said no. That's a mistake that I don't intend to repeat. I have a new set of heads I'm using on this new engine and I've been going at them for hours making sure they're clean as can be.
Nice man, yeah - I had to learn the hard way too. Now, even after I get stuff back from a machine shop, I always clean it twice.

"Nobody cares about your engine as much as you do" (that's what I always say lol)
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Old 10-13-2020, 12:31 PM   #16
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Nice man, yeah - I had to learn the hard way too. Now, even after I get stuff back from a machine shop, I always clean it twice.

"Nobody cares about your engine as much as you do" (that's what I always say lol)
Very true, in the end I did manage to have fun with this engine, and the plans were already in the works for this new engine so it's not like it's completely inconvenient. It would have been nice to strip this engine and sell it off for parts. I'll have to measure of the cylinders and see if it can be saved (perhaps a 100mm bore), I know the pistons are garbage, and of the cylinders looks like that, who know what the crank looks like, assuming contamination is the culprit here. Perhaps the rods are still good? Ha.
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Old 10-13-2020, 04:04 PM   #17
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check your wrist pins and wrist pin bores on the pistons please.

If there's any smearing that would mean that the piston was locking up on the pin which will contribute some to that much wear.
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Old 10-13-2020, 05:12 PM   #18
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Quote:
Originally Posted by JSR84 View Post
Very true, in the end I did manage to have fun with this engine, and the plans were already in the works for this new engine so it's not like it's completely inconvenient. It would have been nice to strip this engine and sell it off for parts. I'll have to measure of the cylinders and see if it can be saved (perhaps a 100mm bore), I know the pistons are garbage, and of the cylinders looks like that, who know what the crank looks like, assuming contamination is the culprit here. Perhaps the rods are still good? Ha.
Might be ok, but like cboggess said, you'll find out when you pull the pistons. If the wrist pin is hard to get out, chances are the small end of the rods would need a little bit of work.

Rods should be fine otherwise; if anything, you would have some damaged rod bearings, which you would replace anyways.
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Old 10-13-2020, 05:29 PM   #19
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The pins have definitely not come out easy, I'll check them when I get home. What would cause the piston to lock up on the pin?
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Old 10-14-2020, 10:54 AM   #20
BeastianSTI
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Some type of oiling/pressure issue. Lots of possibilities. I'd start by getting the wrist pins out and share pics of them, as well as the wrist pins groove in the piston itself.
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Old 10-14-2020, 11:33 AM   #21
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Here is a shot of #2 pin. I thought I had taken a photo of #2 piston, but I guess not. I'll get it later.

If you'll notice the ultrasonic cleaner in the background, I'm not ****ing around this time. Lol

https://photos.app.goo.gl/iK5NkuDdMbgRsYaXA
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