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Engine knocking - possibilities

GR8racingfool

GR8racingfool

New member
Not my car for starters here, but one that came to me.

The '00 GTP sounds horrible. The knocking is too bad to be a coupler, its differently something metal. He says if you give it more throttle, the knock goes away, or quiets down. I have not done this yet to see, like on the open highway or what have you.

Thinking, if thats the case, wasn't the general rule on our 3800's if the knock is there and gets louder as you give it more throttle its probably a rod knocking, and if you give it more throttle and it goes away its probably a flex plate that's cracked?

I think that's correct, but we can always pull the cover off and look up inside and see if we can see damage to the flex plate or move it around and see if it moves more than it should...or drain the oil and see what surprises it has in that or even cut open the oil filter and look in that if its internal damage.

~F~
 


I would guess its the flex plate. The spinning force when it is going fast will probably hold it in its place.
 
Sounds just like the flexplate on my Camaro when it cracked. Made a real bad rattling sound at idle especially, then went away with throttle.
 
Cool.

Ya at idle...its baaaaaad.

I'll have to make time to look into it further. Planning on several mods anyway, so might just pull the engine out and do some needed service to it anyway like oil pan reseal and so forth, be a good time for a cam and headers too. :th_thumbsup-wink: If its the flex plate...then that would just be awesome for him and me. :th_thumbsup-wink:

~F~
 
Pretty sure if you put it under a load and it goes away its a main bearing knock. I had a bad knock though once and especially under startup, then went away slightly, turned out to be the harmonic dampener the rubber separated all around it.
 


It's the harmonic balancer. I just changed mine today with the same symptoms 1 hour job with the right tools.
 
It could be a million of things but on my car i got a great deal when i bought it because there was a knocking but when i was looking at it i noticed that a vac line on the supercharger was slightly broken and was starting to rot. Bought the car brought it home it was knocking in 2 or 3 of the cylinders went to autozone got a 2in line for free and fixed it. the car runs like brand new
 
Checked the SC coupler, nope.
Checked the flex plate, nope.

Checked the dampener...

Harmonic Dampener FTL!:th_crossbones1:

30673287471.jpg


Car was taken to a dealership, dealership said it was a bad engine, estimate for repairs was $6K or $7K total. Owners parked the car, put it on craigs list, and sold it for $1K. :th_biggrin2:

Had a extra dampener laying around so...donated it to the car, so only out time and labor, which was free anyway.

So I think dealerships are good for something after all. LOL

Thanks for your help ya all.

Now we know its not the engine, we can continue on as planned with a build to make it to the 12's. On a budget.

~F~
 
^me either.

I have always heard/read others posting they have seen them fall apart, this is a first for me. Never seen one ever posted online either...just "heard" all the time.

So here we go...broken balancer picture. :th_thumbsup-wink:

~F~
 


X2 on only hearing about it and not seeing it in person or a pic for that matter. How hard was that bolt getting out? mine took like 2 hours....
 
^about 2 seconds with a impact gun, easy as pie.

Takes more time to attach the puller to the balancer than it does to do the rest of the work in getting it off.

~F~
 
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