Help, unknown Knock driving me crazy.

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jun 24, 2009

#1

• Jun 24, 2009

• #1

So I have just installed a teksid 2V with a fresh set of heads.
I have a knock and I cant find where. It is a used shortblock but looked to have very few miles on it and rotated fine before I started the build.

Anyways, I have a knock just above Idle. As I ease into the throttle a little, it shows up. its there before it steps down to idle, then it goes away. when I press the throttle more than just partial, it goes away. It is always there kinda like on the edge of engine load where it is super low. Whenever I ease into the gas it shows up, as I press more, it goes away.

-I have listened with a stethoscope and cannot locate anything. It does not appear to be comming from pan area. Or, the valve covers.

-I disconnected the spark then fuel to each cylinder. I've been told it is the way to check for wrist pin knock. None had an effect on the noise.

-Hooked up a timing light and it seems to be in sync. with the valvetrain (1 knock per 2 rotations). I have tried retarding timig in case it was detonation, no response.

could it be a guide or tensioner problem? I can't get any sound out of the front cover really either.

It sucks to build an engine then have stuff like this. Anyone have an idea?

 

the98stang

Active Member

Aug 12, 2005

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Clovis, CA

Jun 25, 2009

#2

• Jun 25, 2009

• #2

how loud is it? Can you post a vid?

It could be the timing chain....

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jun 25, 2009

#3

• Jun 25, 2009

• #3

I could probably get it on film. I'll work on it.

 

trinity_gt

10 Year Member

Jan 31, 2003

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Canada

Jun 25, 2009

#4

• Jun 25, 2009

• #4

Sounds are the hardest thing to diagnose over the internet but here's another thought: piston slap?

Is it worse when the engine is cold?

Are the pistons factory hypereutectic or are they forged?

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jun 25, 2009

#5

• Jun 25, 2009

• #5

Hypers, not really that bad at cold, kind of constant throughout temp range.

 

Flghtmstr1

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Mar 31, 2005

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Springfield, PA

Jun 25, 2009

#6

• Jun 25, 2009

• #6

Piston slap and timing chain noise were two things I thought of as well, but here's an oddball suggestion: the accessory belt tensioner. Once, I was beating the crap out of my car, and when I stopped, I heard a knock. I thought I had done my engine in. However, it turned out to be the belt tensioner for the 8-rib setup. I replaced the tensioner with a new one, and the knock went away.

 

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D.K

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Jun 17, 2002

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MD

Jun 25, 2009

#7

• Jun 25, 2009

• #7

I had a similar knocking noise coming from my engine. It was only heard at low RPM and was quiet at idle. I thought is was the crank pulley so I replaced it with an SFI damper...no change. Hopefully it'll be something minor for you, but in my case I ended up being greeted by the unmistakable sound of a bad main bearing.

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jun 25, 2009

#8

• Jun 25, 2009

• #8

I ran it without accessory belt, noise was still there.
I listened again with a stetho and it is more predominant on the driver's side and more toward the rear.

Here's a video.http://www.supermotors.net/getfile/739666/fullsize/sany0008.mp4 Its almost 16mb so be patient please.

Also, would piston slap be snycd with the valvetrain speed or the crank? The noise is definitely the speed of valvetrain.

 

trinity_gt

10 Year Member

Jan 31, 2003

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Jun 25, 2009

#9

• Jun 25, 2009

• #9

bnmc98 said:

I ran it without accessory belt, noise was still there.
I listened again with a stetho and it is more predominant on the driver's side and more toward the rear.

Also, would piston slap be snycd with the valvetrain speed or the crank? The noise is definitely the speed of valvetrain.

Click to expand...

Listened to the vid: That's definitely not piston slap. If it was the valve train I wouldn't expect it to change in intensity with engine load or throttle position. Sounds like the makings of a rod bearing going bad...

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jun 25, 2009

#10

• Jun 25, 2009

• #10

Maybe I just don't want to accept a rod knock, but, could it be a lash adjuster?

 

the98stang

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Aug 12, 2005

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Clovis, CA

Jun 26, 2009

#11

• Jun 26, 2009

• #11

that's too quiet to be piston slip....I don't even think it's a wrist pin or rod bearing....however it seems too loud for a lifter noise or lash adjuster....

have you done a compression test? That is definitely in sync with the valve train...

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jun 26, 2009

#12

• Jun 26, 2009

• #12

accidental post

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jun 26, 2009

#13

• Jun 26, 2009

• #13

Posted via Mobile Device i have not run a compression check. what are your thoughts?

 

Intercoledc6

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Jun 19, 2009

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Jun 28, 2009

#14

• Jun 28, 2009

• #14

That my friend is a lifter or part of the valve train, pull the valve cover you should see the problem. Are they hydraulic lifters or mechanical?. To me it sounds like a loose rocker,Does not sound like nothing to serious, maybe just valve adjustment...

Larry

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jun 28, 2009

#15

• Jun 28, 2009

• #15

I will pull the valve cover soon. A collapsed lifter might pump up as rpm goes up and oil press. right? I am looking for excessive lash correct?

 

the98stang

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Aug 12, 2005

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Clovis, CA

Jun 29, 2009

#16

• Jun 29, 2009

• #16

put a stethoscope on the valve cover and listen for the noise...that way you won't have to remove them.

I would still do a quick compression test...

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jul 1, 2009

#17

• Jul 1, 2009

• #17

Did compression check. lowest was 173 highest was 185, no leakdowns.

I also replaced my whole drivers side with followers and lash adjusters I know work from my old engine. Did not solve problem.

knock is not present at startup cold and as engine starts to warm it appears.
Just put 1500 miles on it and it did not get worse. Only happens at 0 load on the engine. goes away at idle and goes away at about 1/3 load and up. I push the clutch in and it is still there. It is predominant at the back of the engine, and I can hear it in the oil pan area. But, still it is sync'd with the valvetrain as far as rpm.

I did have one problem with the oil pan scrapers getting hit by the rods at first, but I bent those out of the way. It should not be them, besides that would be every rotation not everyother, right? Unless the power stroke is pushing it into the scraper. I just don't know.
I am temped to just run it and let it get worse or maybe it won't do anything.

Opnions?

 

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Str8Kr4zy

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Jun 30, 2004

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Oklahoma

Jul 3, 2009

#18

• Jul 3, 2009

• #18

Might be a tensioner ..if there is any slack in the timing chain it will smack against the guide and cause a kind of ticking/knocking sound. Im in the process of replacing mine.

It wasn't heard at all at idle or even around 1500 rpm, but anything above that and you could. Also, if i had a gradual increase in speed, it seemed nonexistent.

If I got to a certain rpm above 1500 with out increasing my speed steadily, then the tick/knocking would pop its ugly head out and embarrass me in front of the chicks with the Honda civics...

I thought I'd be able to tell by just removing the valve covers and checking for any slack that way, but i was wrong, had to take the timing cover off to really get a good look at it.

Really worth looking into if you don't believe its anything else and you're symptoms are close to this. Hope this helps.

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jul 4, 2009

#19

• Jul 4, 2009

• #19

Yeah, I am going to check the tensioners out. I was looking at the left one when I changed out the valvetrain and when I would roll the motor over by hand, I could see the tensioner shaft extend at one point in the rotation and make a slight click. I used my 4V chains and tensioners, I thought I got all the gum out of them, maybe not. I have a set of tensioners sitting around that I know work. I'll give it a try. Thanks

 

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bnmc98

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Mar 24, 2009

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Bozeman MT

Jul 6, 2009

#20

• Jul 6, 2009

• #20

Not the tensioners or chains, just replaced them with ones from my old motor that I know work properly. Oh well, I'v had her up to 6K and haven't popped. Guess I'll drive it til it goes away one way or another.