how to diagnose knock

5.0TailPipeHump

Member

Dec 5, 2006

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Aug 12, 2010

#1

• Aug 12, 2010

• #1

Well problem is a have a knock in the engine , i had an ear scope on the motor

around the pan area and hear it from under there, the engine has 14 thousand

km on her . I was told if i remove 1 spark plug wire at a time and the noise

goes away that it would be a busted piston or a rod bearing, what about a

lifter or rocker ? i had the ear scope on the valve covers and i did not hear it

as bad as i did under the oil pan. Here's a video of the noise i'm dealing with.
Rod bearing :: AMBA0004.mp4 video by saw426 - Photobucket

 

will1992

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Aug 25, 2005

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Aug 12, 2010

#2

• Aug 12, 2010

• #2

man that sucks, my cousins car started doing that, and one day he ended up replacing it with a junkyard engine, it blew

 

fox2300

New Member

Aug 12, 2010

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Aug 12, 2010

#3

• Aug 12, 2010

• #3

If you remove a spark plug wire and it doubles in frequency, that is a piston skirt or wrist pin. A rod knock will be louder under engine acceleration usually, and I don't think you would confuse a lifter or rocker noise for a knock, that is usually described as a click or ticking noise. When did the noise start, and what are your driving habits? If you are 83+ years old and have white hair, you could have carbon built up on the pistons hitting the cylinder head, let your grand son "blow the soot out" and it will stop knocking. If you are the grand son, you probably have other issues.

 

BlackGT89

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Dec 16, 2002

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Huntsville, AL

Aug 13, 2010

#4

• Aug 13, 2010

• #4

Wow, I think you've got the problem right there on camera ! That crankshaft pulley seems to really be wobbling in time with the noise. Make sure it's tight. Maybe your damper / balancer is going out as well ? Are you getting any vibration ?

 

T

tiptopss

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Apr 27, 2009

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Aug 13, 2010

#5

• Aug 13, 2010

• #5

ya, good catch there blackgt89, ya it sure does looks like there is something with the harmonic balancer, something is outta whack there, also you can tell that the sound is externelly and not internal, so that is a good thing.

Just remove the serpentine belt, once the pressure is off of the harmonic balancer, you then will be able to tell if it is bad or not, well you should be able to anyway, it just looks loose to me.

 

BlackGT89

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Dec 16, 2002

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Huntsville, AL

Aug 13, 2010

#6

• Aug 13, 2010

• #6

Yeah, looks like there is just too much movement there. I know on the SHO we used to have you had to be really careful about the crank bolt working it's way loose and causing what was called crank cancer, because after you noticed the noise it was usually so bad it was almost terminal. YouTube - Yamaha SHO V6 Crank Cancer

Your noise sounds a little different though. Check the crank pulley first, the under-drive pulley bolts are usually really hard to get to and tighten properly.

 

5.0TailPipeHump

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Dec 5, 2006

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Aug 14, 2010

#7

• Aug 14, 2010

• #7

Thanks people, ill remove my serp belt and have a listen and update. Hoping its minor.

 

5.0TailPipeHump

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Dec 5, 2006

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Aug 15, 2010

#8

• Aug 15, 2010

• #8

BlackGT89 said:

Wow, I think you've got the problem right there on camera ! That crankshaft pulley seems to really be wobbling in time with the noise. Make sure it's tight. Maybe your damper / balancer is going out as well ? Are you getting any vibration ?

Click to expand...

Thanks abunch blackgt89, you hit the nail on the head , took off the belt started the car no noise , grabbed the crank and she was loose by 2 bolts , snugged em up and bam no more tappy tappy . Again thanks much!

Garry

 

BlackGT89

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Dec 16, 2002

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Huntsville, AL

Aug 15, 2010

#9

• Aug 15, 2010

• #9

5.0TailPipeHump said:

Thanks abunch blackgt89, you hit the nail on the head , took off the belt started the car no noise , grabbed the crank and she was loose by 2 bolts , snugged em up and bam no more tappy tappy . Again thanks much!

Garry

Click to expand...

Excellent. Glad to help !

 

madspeed

Colonel Mustard

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Nov 29, 1999

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a van down by the river

Aug 16, 2010

#10

• Aug 16, 2010

• #10

Wait, sounds kinda like mine. I can start it up w no belt?

 

BlackGT89

Member

Dec 16, 2002

774

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Huntsville, AL

Aug 16, 2010

#11

• Aug 16, 2010

• #11

Yep, just run it long enough to see if the noise goes away. But you might not even need to crank it up, just take the belt off and spend the pulleys by hand (maybe give them a shake) and see if anything seems loose or has roaring bearings.

 

madspeed

Colonel Mustard

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a van down by the river

Aug 16, 2010

#12

• Aug 16, 2010

• #12

Thx for the tip, i gotta check mine out