S2000 Under The Hood S2000 Technical and Mechanical discussions.

piston slap

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Old 01-22-2016, 05:46 PM
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Hey seeing if any of you guys out there have had any f20c motors get piston slap? I bought a 01 s2k with 77k with a knock guessing I would be replacing the motor and low and behold it turns out the previous owner tried looking into the problem. He machined the crank and rods I'm guessing thinking that was the problem/maybe was a problem. The noise is number 1 and 4 piston slapping the cylinder wall. I have sent the block out to get honed .25 for Honda's oem oversized pistons. I have had multiple people tell me to just buy a jdm and call it a day, but I'm finding the motor to be very fresh with lots of life left in it as long as the cylinder walls come out nice. Not sure what caused this tho could this be a motor that was driven hard without the new oil jet bolts? Or maybe just a owner who didn't check the oil? I'm going threw things on the engine trying not to miss anything...

I originally checked the tct found it to have looked replaced already but replaced it anyway. That wasn't it, also ran with serp belt off just to be sure before i went down this road. Transmission stopped shifting into second after about two days of messing with it I truly believe the two people before me who owned this just did a awful job of upkeep/just were relentless on her. I ordered a new ap2 trans/new clutch,pp,flywheel pilot and throw out bearing. I see everyone with ap1s replaces the valve spring retainers/keepers with ap2 oem equipment but only the intake side? Do people replace the exhaust side with ap1 retainers or does nobody have any troubles with the exhaust side at all? Hoping at the end of this to have a real nice driver but who knows things keep going like this...
Old 01-23-2016, 08:08 AM
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I bought an 01 F20C with 111k from a member here and the motor has piston slap. My 02 with 150k on the other hand has no piston slap.

The motor with piston slap is OEM and untouched. It did have lower-ish compression at 205 PSI. I think people just live with it for the most part.
Old 01-23-2016, 08:11 AM
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As for the valve retainers, you only replace with intake side with AP2 retainers. Before you go about replacing them you can do a basic visual check first. Search it up. I'll have a FIY video soon. I'll be replacing mine shortly.

Also this is only for AP1 motors btw.
Old 01-23-2016, 08:12 AM
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As for the shifting issue, check the clutch fluid, then look for a master cylinder leak, or try adjusting the clutch pedal freeplay. At the very least you should try bleeding the clutch fluid.

See this video I made

[media]http://www.youtube.com/watch?v=l6gtErFxm5U[/media]
Old 01-26-2016, 04:05 AM
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Ok thank you for the reply. I checked the retainers and #1 intake was cracked. As for the transmission the 1-2 shift sleeve was ground down. I'm still waiting to hear back from the machine shop hoping it comes out nice! Thanks again
Old 01-26-2016, 10:19 AM
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Piston slap isn't a common naturally occurring issue on this engine. After reading that your #1 valve retainer was cracked, that makes me think you may have had an over rev valve to piston contact, and that not only would bend a valve but could possibly cause wrist pin fatigue if they did indeed make contact, and therefore cause piston slap. I'm not saying that's what happened, but its an educated guess, in which I would investigate further. I would examine cylinder #4 valves hard. Oil starvation would typically manifest as main bearing failure first. If this was addressed, then possible the wrist pins and pistons were fatigued and overlooked during the recon. Id typically expect to see some cylinder scoring at that point as well though. abnormal lower compression in one or multiple cylinders may elude to that. Its always an investigation game and putting the pieces together to figure out the story on a troubled engine. Its not easy to pinpoint the culprit sometimes.
Old 01-26-2016, 04:39 PM
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Originally Posted by s2000Junky
Piston slap isn't a common naturally occurring issue on this engine. After reading that your #1 valve retainer was cracked, that makes me think you may have had an over rev valve to piston contact, and that not only would bend a valve but could possibly cause wrist pin fatigue if they did indeed make contact, and therefore cause piston slap. I'm not saying that's what happened, but its an educated guess, in which I would investigate further. I would examine cylinder #4 valves hard. Oil starvation would typically manifest as main bearing failure first. If this was addressed, then possible the wrist pins and pistons were fatigued and overlooked during the recon. Id typically expect to see some cylinder scoring at that point as well though. abnormal lower compression in one or multiple cylinders may elude to that. Its always an investigation game and putting the pieces together to figure out the story on a troubled engine. Its not easy to pinpoint the culprit sometimes.
Thank you for the info! I will inspect all valves especially #1 and #4. Im replacing the retainers anyway but ill go threw the exhaust side now too. As far as the pistons they don't look like they have had contact with anything but they could've been changed. I just got the call for the block it came out great my guy said so Im going to pick that up tomorrow + the ap2 trans came in today. Just waiting on some parts and I will start the rebuild. Thanks again!!
Old 01-26-2016, 05:39 PM
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Originally Posted by clay.anders
Originally Posted by s2000Junky' timestamp='1453835988' post='23863193
Piston slap isn't a common naturally occurring issue on this engine. After reading that your #1 valve retainer was cracked, that makes me think you may have had an over rev valve to piston contact, and that not only would bend a valve but could possibly cause wrist pin fatigue if they did indeed make contact, and therefore cause piston slap. I'm not saying that's what happened, but its an educated guess, in which I would investigate further. I would examine cylinder #4 valves hard. Oil starvation would typically manifest as main bearing failure first. If this was addressed, then possible the wrist pins and pistons were fatigued and overlooked during the recon. Id typically expect to see some cylinder scoring at that point as well though. abnormal lower compression in one or multiple cylinders may elude to that. Its always an investigation game and putting the pieces together to figure out the story on a troubled engine. Its not easy to pinpoint the culprit sometimes.
Thank you for the info! I will inspect all valves especially #1 and #4. Im replacing the retainers anyway but ill go threw the exhaust side now too. As far as the pistons they don't look like they have had contact with anything but they could've been changed. I just got the call for the block it came out great my guy said so Im going to pick that up tomorrow + the ap2 trans came in today. Just waiting on some parts and I will start the rebuild. Thanks again!!
Let us know how it turns out, it sounds like you should be completely sorted and left with a very nice and reliable S2K after all that is completed and reassembled
Old 01-27-2016, 03:32 AM
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Originally Posted by s2000Junky
Piston slap isn't a common naturally occurring issue on this engine. After reading that your #1 valve retainer was cracked, that makes me think you may have had an over rev valve to piston contact, and that not only would bend a valve but could possibly cause wrist pin fatigue if they did indeed make contact, and therefore cause piston slap. I'm not saying that's what happened, but its an educated guess, in which I would investigate further. I would examine cylinder #4 valves hard. Oil starvation would typically manifest as main bearing failure first. If this was addressed, then possible the wrist pins and pistons were fatigued and overlooked during the recon. Id typically expect to see some cylinder scoring at that point as well though. abnormal lower compression in one or multiple cylinders may elude to that. Its always an investigation game and putting the pieces together to figure out the story on a troubled engine. Its not easy to pinpoint the culprit sometimes.
Piston slap IS a naturally occurring noise on these cars, as with any engine with forged internals; every S2000 I've ever started cold exhibits it for a few moments until the metal expands. You have to know what you're listening for and not guess. I've owned 6 S2000's ranging from 30xxx miles up, they all do it.

Don't believe me? Ask Billman...
Old 01-27-2016, 04:06 AM
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In my experience, they all have it.

It is most noticeable right after morning fast idle, just as engine speed lowers. It is a slight knocking that comes and goes frequently, for a few min, and completely disappears once warm.


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