how to diagnose knock

[5.0TailPipeHump]

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]

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

 

[fox2300]

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]

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 ?

 

[tiptopss]

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]

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]

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

 

[5.0TailPipeHump]

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 ?

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]

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

Excellent. Glad to help !

 

[madspeed]

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

 

[BlackGT89]

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]

Thx for the tip, i gotta check mine out