2004 GTP engine noise help please?

[cadltrk]

I am new to this forum and also am new to the Grand Prix world. I just bought a 2004 Grand Prix GTP that needs a little work. It starts, runs and drives just fine but has a NASTY noise that I originally thought was from the top end. I bought it cheap from a friend, he thought that it may be the supercharger. I looked and listened a little closer with another friend. He thought that it was an internal issue. We took the belts off and started it up for a quick second and still had the noise. I figured that this ruled out any of the front engine components including maybe the supercharger? The noise gets louder and quieter at idle and almost sounds like a flapping noise along with a knock of sorts. I have done my share of repair work on cars but definitely I am no pro.

My questions are:
#1 What are the potential issues I am up against?
#2 Is it possible for the supercharger to be an issue, even if the noise was there after removing the belt?
#3 Are there any other fairly simple checks I should try?
#4 What could cause a noise this bad and the car run and drive ok?
Thanks for your help!

[TheOtherNick]

could be a lifter. It is not the supercharger. Pull the plugs and see if any are bent that would be a chipped piston.

[mikedinthecity]

check the oil...any metal in there? sorry to say it might be the engine......probobly started with the chipping of the piston which i think strongly is due to long term regular 87 octane fuel.......or various other things. talking stock engine no mods etc, normal to light abuse...premium fuel is much better for the supercharged 1s.

[blueguy]

could be a lifter. It is not the supercharger. Pull the plugs and see if any are bent that would be a chipped piston.

this guys post.

[cadltrk]

I have pretty much figured that I will need to do some engine work. I am guessing that it might just be simple to buy a motor from the salvage yard and do a swap. Other than being time consuming, Is this a very hard job? Are there any tricks or helpful information that would make this easier? Will it come out from the top without lowering the subframe?

[OH4CompG]

If it's just a lifter, you're only out maybe a hundred dollars in gaskets and fluids to swap it....

[cadltrk]

I inspected the plugs and drained the oil last night. Everything checked out ok there. Has anyone heard of this bulletin about an inspection cover on the tranny making noise? I also see that the supercharger still turns without the belt, maybe it could still be the culprit?

[Bio248]

the blower will still spin without the belt since there is air still being sucked through the rotors. you can probaly hold it still if you want to.

[supercharged06]

I had the same problem....i got a new motor out of warranty. your connecting rod and or wrist pin is gunna go very soon. My # 5 cyl was the culprit

[cadltrk]

I think that it must be a rod bearing. I have found an engine and I am gonna try the swap on my own. Any tips or tricks that I would find useful?

[99GPGTP]

start the engine and and disconnect one injector at a time and listen for the knock noise to get quieter and that is the cylinder that is knocking.