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PIston slap

  
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PIston slap

 
zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 10/17/13
04:37 PM

I finally diagnosed my engine knock as piston slap after a few months of changing parts, elimininating things it "could" be. Here's the question, I know that the piston in question has excess clearance for some reason and that clearance is allowing movement of the skirt as it travels up and down. before I go further, these are Keith black Hypereutectic pistons on Eagle forged rods with 8000 miles on them. should I drive it as it is or, should I tear the engine down now? some of you out there with more experience with this issue than I please lend your expertise. I have done all the tests, and the engine has good oil pressure so it's NOT bearing related, I did a cylinder balance test and all cylinders are working as they should, plugs all look good, no oil consumption. No knocking at an idle but as the RPM'S come up the knock appears. Let me know what you think, it's winter so I'm not driving the car anyway but I'm also not too anxious to pull the engine. thanks zman  

Dave632 Dave632
Addict | Posts: 2218 | Joined: 07/08
Posted: 10/17/13
07:57 PM

I would be worried that there was a broken skirt on the piston causing the piston to rock and make the noise you hear. This could cause the piston to fail especially if there is any high rpm action. If you are putting it away for the winter it sounds like the ideal time to take it apart.
My Beretta used to come apart every few months. I could pull the engine by myself in under 2 hrs.  
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zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 10/17/13
08:14 PM

Hi Dave, Yeah, that's kind of what I thought I should do. Just being lazy not wanting to pull it apart. I guess I'll need a new set of pistons anyway. Good excuse to step up to the forged pistons anyway. You can look at the engine and car on my thread a few months ago on my MSD Atomic Injection install. thanks for the input. Z  

Dave632 Dave632
Addict | Posts: 2218 | Joined: 07/08
Posted: 10/18/13
07:47 AM

Yea, I have always found it better to get it over with than to put it off and say I should have done that in the past.  
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68scott385 68scott385
Guru | Posts: 1990 | Joined: 10/09
Posted: 10/19/13
12:01 AM

Does it make the noise only in cold weather, when the motor is cold or all the time?

A friend had a Furd that had a piston slapping all the time and he drove it like it was stolen all the time for several months until it broke a skirt.

I have a 200K+ 5.7 Vortec that has a noisy piston when the motor is cold during the winter months. I noticed it several years ago and let it warm up a minute or three before driving. Yes it is getting worse in that it is noticeable in slightly warmer weather than it once was and sometimes it seems that it takes longer to quite down. If I was in a place that I could pull it and go through it I would but until then it gets treated gently.

Just a couple of my experiences and some BS to take up space/...  
68scott385 68scott385 68scott385

zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 10/20/13
02:02 PM

It's coming out. If I wait until something breaks it will just cost more.