Piston Slap.. - Page 3 - Chevy Nova Forum
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Old 25th-January-2013, 01:58 PM   #31
Dan_Lockwood

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Quote:
Originally Posted by JRouche View Post
I dont think there is interference with the valve cover. They are nice large cast units. http://www.gmpartsdirect.com/results...umber=10185064

Yeah Jackel I did use the handy dandy stethoscope. Did that way back when. I forgot to talk about that. So...

I checked ALL around the engine. The intake, heads, header tubes, block, oil pan, valve covers. You name it, I was all over it. The passengers side is quiet. The #5 (third cylinder back from front on drivers side) seems to be the culprit. Thats from listening to the header tube. Its real obvious when hitting the tubes. No sound at all from the block anywhere. No sound from the pan. The head (drivers side) is pretty quiet but I get the usual ticking from the valve train, no heavy noise. Same with the intake.

I really only hear it on the header tube with the scope.

But... I can hear it 20 feet away when the car is idling on the driveway and Im in the garage.

Thanks again, JR.
Talk about piston slap, all the new 110" Harley CVO's have it like there's no tomorrow. My '08 had it and my '09 had/has it big time. Of course MOCO says it's normal...

Anyway, since you may have found the culprit, try pulling the plug wire off on #5 and see if the noise goes away. I had an old mechanic that worked for me at a dealership years ago and he did this a lot and it does seem to pin point the cylinder quite well. Next you have to determine if it's a piston slap, wrist pin, or possibly a cracked piston.

I traded years ago and ended up with a 300/327 in a '66 Vette that had a slapping knocking noise. I drove it for some time, maybe a couple thousand miles and traded it off to my brother. He did the same and traded it to another guy. That guy pulled down the motor and one of the pistons came out in two pieces. So that 327 ran for several years and 1000's of mile with a cracked/broken piston.

Noises are very hard to detmine the cause and being an arm chair mechanic is even harder.

I agree with some of the others, if it's that loud, I'd bite the bullet and tear it down and have a look see.

I guess before I'd pull the motor for a look see, I'd pop the left valve cover off just to make sure nothing top side has run amauk.

Good luck with your noise.
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Old 25th-January-2013, 03:06 PM   #32
greggbruceauto

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sounds like valvetrain speed to me..... Had a loose valve guide once on a 2 month old 're manufactured' (nationwide re manufacturer) engine I installed for a customer.... ended up putting new heads on it, noise gone, customer put another 170k miles on that engine with no further problems before he sold it. I found the culprit by using a straight prying device laid parallel to the valve spring and moving it against and away from the valve spring -- shouldn't move more than a couple to 5 thousandths of an inch .005" -- just be careful you're not actually bending the valve stem and counting that as play.
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Old 26th-January-2013, 12:34 AM   #33
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Ok. Im over whelmed with ALL the great replies. THANK you ALL.

Im a lil ashamed with trying to troubleshoot my issue with a simple sound recording. I KNOW its NOT the way to go.

I was trying to capture the sound I hear from 10 feet away from the car and I screwed up and put the recorder right next to the engine (on the radiator support). Because the ear can pick up the sound and it over rides the common engine sounds.

Not so with the recorder. I watched (listened)
the recording and totally get why it sounds like there is some valve train issues or other issues, there is ALOT of noise on the recording, even the inrush of air from the intake on some parts.

The recording amplified ALL the standard noise you will hear from a perfectly running engine along with the road noise. The major amount of sound you hear on the vid is the headers and road air noise.

Exhaust gases hitting the primary tubes is VERY metallic. And will sound like a metal on metal "hit" when recorded up close. MY BUST!! Solly guys.

The engine is smooth and there is NO metallic sound in person. No higher pitched sounds (tick) like what you get with a valve train issue.

And its not a deep sound like its in the bottom end. Its a piston slap sound that for the life of me I cant reproduce with what I have

I do think I have to yank the engine and thats far from my project list. She was at the top of the list and I did what was essential, so I could drive her.

She has been my project car from 1995. Unfortunately she has moved down some. Other projects now take presidence if an engine overhaul is due. I have a CNC mill thats on the front burner right now.

Ill pull the #5 plug to see if the noise changes. If it does then I know Im in for a tear down. Not a prob. Im retired (have the time, not much money) and would rather yank the engine and find SOMETHING than NOT pulling her out and wait for real damage right?

No way do I want to continue to drive the car as is. There is a problem and I want to find it. Im not into waiting to see if it gets worse then fixing much more.

I already know its not a simple cold start piston slap issue even though it started out as that, things have changed. Shes noisy when warm. That should have been my clue to stop driving the car and investigate.

And with ALL the help from YOU guys thats whats gonna happen. My 62 is side lined till I make the garage ready for a full on looksee.

I really DO thank ALL of you for helping out. Great bunch of folks here.

Ill be sure to post some updates with what I find. It might help others down the road. Thanks SNS members!!!!! JR
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Old 26th-January-2013, 12:15 PM   #34
larrywalk

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Although diagnosis via video sound is hard to do, the first thing I'd check is for a blown exhaust header gasket - it's happened to me before and sounds similar.
To verify, at idle, I cautiously feel for exhaust gas puffing out around each of the tubes where they mate to the head - and try not to get burned!

Good luck!
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Old 1st-February-2013, 10:43 AM   #35
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Check the easy stuff first before you pull the engine.

True story: A mechanic I worked with showed up one day with a really nice sixties c series red and white pickup. I was struck by the absolutely beautiful condition. I said, "How much did you have to pay for this find?". I don't remember now the exact price, but it was too good to be true. I said "BS".

He said the guy sold it so cheap because after investing thousands into the restoration and engine rebuild, the truck had a persistent knock that drove him crazy. He sold it in disgust and anger to my friend at a tremendous loss just to get rid of it. I said, I didn't hear any knock when you drove in. He said when he checked it out, it was just a loose torque converter bolt! He tightened it up and it ran great.

You are going to kick yourself if you pull the engine only to find it was a leaking gasket or other simple problem as described in the posts above.

Rule everything else out first. If all those are good then you may still have to pull it, but don't be so hasty until you make a list and methodically check them all.
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Building a small, high rpm engine
with the perfect bore, stroke and rod ratio is very impressive...
like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.

Cubic inches is like Indiana Jones with a cheap pistol.
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Old 1st-February-2013, 10:59 AM   #36
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My first car was a 70 Nova 4 door and it started a knocking sound. I traced it to the converter like Paul said above. It had one bolt in it and it was loose, the other two had fallen out. I replaced the bolts and no more noise.
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Old 1st-February-2013, 04:00 PM   #37
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Quote:
Originally Posted by Paul Wright View Post
Check the easy stuff first before you pull the engine.

True story: A mechanic I worked with showed up one day with a really nice sixties c series red and white pickup. I was struck by the absolutely beautiful condition. I said, "How much did you have to pay for this find?". I don't remember now the exact price, but it was too good to be true. I said "BS".

He said the guy sold it so cheap because after investing thousands into the restoration and engine rebuild, the truck had a persistent knock that drove him crazy. He sold it in disgust and anger to my friend at a tremendous loss just to get rid of it. I said, I didn't hear any knock when you drove in. He said when he checked it out, it was just a loose torque converter bolt! He tightened it up and it ran great.

You are going to kick yourself if you pull the engine only to find it was a leaking gasket or other simple problem as described in the posts above.

Rule everything else out first. If all those are good then you may still have to pull it, but don't be so hasty until you make a list and methodically check them all.
Cool, Paul is back! Pay attention to what he wrote. Paul is the voice of reason around here.
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Old 5th-February-2013, 02:35 AM   #38
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Quote:
Originally Posted by larrywalk View Post
Although diagnosis via video sound is hard to do, the first thing I'd check is for a blown exhaust header gasket - it's happened to me before and sounds similar.
To verify, at idle, I cautiously feel for exhaust gas puffing out around each of the tubes where they mate to the head - and try not to get burned!

Good luck!
You are so right. I have had exhaust leaks that sounded like some major metal on metal issues.

Thanks for checkin in. The exhaust is sealed. JR
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Old 5th-February-2013, 02:47 AM   #39
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First off thanks for replying. Ive always been a fan of your technical skills Paul. Nice to see your voice again.

I agree. Im not in a hurry to pull the engine. Some of the points that might be the cause will need an engine pulling.

But that really is the LAST resort. If I yank the engine I will break it all down and do an autopsy on it.

I dont suspect any breakage and I wont pull the engine until I cant troubleshoot it from the engine compartment. Its just hard to work on the engine anymore while its in the car. Getting too painful. Sucks cause Im not that old.

Thanks for the input Paul and good to see yer name again... JR




Quote:
Originally Posted by Paul Wright View Post
Check the easy stuff first before you pull the engine............

You are going to kick yourself if you pull the engine only to find it was a leaking gasket or other simple problem as described in the posts above.

Rule everything else out first. If all those are good then you may still have to pull it, but don't be so hasty until you make a list and methodically check them all.
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Old 5th-February-2013, 02:53 AM   #40
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Originally Posted by sbc1320 View Post
My first car was a 70 Nova 4 door and it started a knocking sound. I traced it to the converter like Paul said above. It had one bolt in it and it was loose, the other two had fallen out. I replaced the bolts and no more noise.
Thats an easy check see for me. Ill raise the car and check the converter bolts. JR
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Old 5th-February-2013, 02:55 AM   #41
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Cool, Paul is back! Pay attention to what he wrote. Paul is the voice of reason around here.
Right? I missed Paul's interaction. JR
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