Piston pin bad ?
- Thread starter mbaird
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Inertia
Well-Known Member
You may be okay,, depending on if whatever it swallowed damaged any valve seats..
Find any foreign objects..
I was changing a starter drive outta my hemi,, the circlip on the starter shaft flew off, and bounced off a few things in the shop,, I couldn't find it,, so got another,, The next Sat I put in the starter, fired my car up to go to the track, and found the clip.. It had gone kitty corner across my shop,, and down one of my four bbls,, into a cylinder,, AND another cyl.. never found any pieces, but lots of impressions, and just had to touch up the valve seats,,
hope you're that lucky..
Find any foreign objects..
I was changing a starter drive outta my hemi,, the circlip on the starter shaft flew off, and bounced off a few things in the shop,, I couldn't find it,, so got another,, The next Sat I put in the starter, fired my car up to go to the track, and found the clip.. It had gone kitty corner across my shop,, and down one of my four bbls,, into a cylinder,, AND another cyl.. never found any pieces, but lots of impressions, and just had to touch up the valve seats,,
hope you're that lucky..
That's what I am wondering.
Never found anything, so why is the motor still knocking? I am hoping it is preignition from the piston damage. Still have to take the other head off. But the only plug damaged was #8! Might have killed that rod or bearing?
I'm no engine guru by any stretch of the word, but I have never heard detonation sound like that at an idle. It sure sounded like something clanking around in there.
This is not good ! All but #6 rockers are binding up when moved beyond full lift !
I spent a lot of time shimming and checked to see id there was oil com through the holes during breakin !
I did have to get replacement shafts and one rocker after inspection of new parts from Hughes... One rocker was missing the roller and the shafts ballooned during as per instruction assembly ...making it impossible to slide rockers on and off shafts !
Oops...forgot to load pic.
I spent a lot of time shimming and checked to see id there was oil com through the holes during breakin !
I did have to get replacement shafts and one rocker after inspection of new parts from Hughes... One rocker was missing the roller and the shafts ballooned during as per instruction assembly ...making it impossible to slide rockers on and off shafts !
Oops...forgot to load pic.
txstang84
Well-Known Member
Are those KB pistons? If they are I'm sticking with my guess of too close a ring gap...when the ends butt together they pop the crown. Seen it before on a 351...guy used standard .004" per 1" of bore...
Mad Dart
Nothing to see Here!
That noise is not a main or rod knock. Whatever was in that cylinder is probably now in your exhaust system.
Those valve seats are probably now toast. Can you see light coming through the valve seat when they are closed? Valves may be bent and were intermittently hanging open and that noise could have been the valve stem bouncing on the rocker arm. I would think your push rods on that cylinder would be bent. Roll them on a piece of glass.
Those valve seats are probably now toast. Can you see light coming through the valve seat when they are closed? Valves may be bent and were intermittently hanging open and that noise could have been the valve stem bouncing on the rocker arm. I would think your push rods on that cylinder would be bent. Roll them on a piece of glass.
txstang84
Well-Known Member
Wow...I hate engine carnage, although it's interesting to investigate. Really happy for you that the cylinders aren't gouged.
GEO
Sarcasm Inc.
I'd be interested to see the pistons when they come out
moper
Well-Known Member
I'm thinking the rockers are intermittantly binding and the clack is the rocker "unbinding" and the valve slamming shut. With the ping damage I'd also look over the cap and wires - make sure there's not an crossfire going on anywhere.
nm9stheham
Well-Known Member
^^ Yeah, it sounds like a valve train noise from something binding and being slapped loose, not a piston or rod/crank. I would check the valve stems, guides, etc., very carefully. You may have some gum formed in a guide or 2 causing a valve to jam open. It'll sound like your recording.
Ths picture of number 8 piston top looks like simple moisture corrosion; did you say this has been in storage for 5-7 years? If so, one or more cylinders will have it's valves open all the time, and moisture will get in. Happens commonly on small aircraft engines that sit idle for some time. You fill the cylinders with special oil for storage to prevent the corrosion. (easy to drian on small aricraft engines, hard to remove from car cylinders....) If you get the pistons out, look around the number 8 rings to see if there is a little bit of rust on them or in the groove and for pitting on the cylinder walls.
Ths picture of number 8 piston top looks like simple moisture corrosion; did you say this has been in storage for 5-7 years? If so, one or more cylinders will have it's valves open all the time, and moisture will get in. Happens commonly on small aircraft engines that sit idle for some time. You fill the cylinders with special oil for storage to prevent the corrosion. (easy to drian on small aricraft engines, hard to remove from car cylinders....) If you get the pistons out, look around the number 8 rings to see if there is a little bit of rust on them or in the groove and for pitting on the cylinder walls.
Inertia
Well-Known Member
I've seen lotsa detonation damage,, usually to a specific area of the piston,, but I've never seen it cause damage to the steel valve head.. I gotta belive it ate something...
Assembled short block several years back . Coated holes and pistons with wd40 and bagged it up tight. Just did cam , valvetrain and heads a few months ago . All new parts.
I would agree that it looks like something was bouncing around in there but how did it get in and out without damaging the valve face or seat ? I think what we are seeing on the chamber and valves are from the piston pieces flying around.
I would agree that it looks like something was bouncing around in there but how did it get in and out without damaging the valve face or seat ? I think what we are seeing on the chamber and valves are from the piston pieces flying around.
Inertia
Well-Known Member
Detonation damage is usually around the circumference,, and usually worst on the side opposite the spark plug..
That looks like its been shot peened..
My eyes must be getting old,, I didn't see any piston pieces missing..
Is there a better pic of the piston missing a piece.. thnx?
How far did you advance the cam,, ?? That could certainly aggravate detonation.
That looks like its been shot peened..
My eyes must be getting old,, I didn't see any piston pieces missing..
Is there a better pic of the piston missing a piece.. thnx?
How far did you advance the cam,, ?? That could certainly aggravate detonation.
txstang84
Well-Known Member
Nah, I don't think your eyes are old-I was looking at the pictures on a damn phone-wasn't near an actual monitor. After looking at them again, I can't really tell if anything's missing-but I hope the OP does find what's making that friggin' noise. moper might be on to something there with the assertion of binding rockers...
Forgive me for throwing this out there if I'm wrong. But this looks like water corrosion on the tops. You said this engine was built many years ago? Looks like moisture got in the engine and caused the pitting? I really don't think it has anything to do with your noise.
There are small bits of piston that have chipped off all over top of the piston.
The knicks in the valves and chamber are probably from them.
As far as the noise... I believe a previous poster was correct in thinking that it was the
siezed rockers hold the valves open then slamming shut. This would explain the clanking noise , the lean condition and the rough idle . It would also explain why I thought the engine seemed to be running rich while burning #8 piston..
The knicks in the valves and chamber are probably from them.
As far as the noise... I believe a previous poster was correct in thinking that it was the
siezed rockers hold the valves open then slamming shut. This would explain the clanking noise , the lean condition and the rough idle . It would also explain why I thought the engine seemed to be running rich while burning #8 piston..
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