My 2004 Pontiac grand prix has a steady clanking noise from the engine and gets worse with acceleration. Any ideas what it might be?

Asked by Jonathan Feb 24, 2014 at 12:33 PM about the 2004 Pontiac Grand Prix GTP

Question type: Maintenance & Repair

7 Answers

Loud? Thrown piston rod, broken valve stem or such,.....not so loud? Valve tappets, something on serpentine belt pulley, there is a LOT of guesswork here

2 people found this helpful.
10,635

Did it come on suddenly (cracked flywheel), or is it getting worse over time ? (rod bearing).

Happen suddenly. I was going 75 thru I95 from jackson mi to BC mi and back and it just happen

10,635

Piston rod bearing is a reasonable guess. There is virtually no test to confirm this without tearing down the engine. If the engine is running okay other than the noise, its worth fixing.

18,225

While I generally agree with Norm's advice I'd disagree on this one. It's 10 years old and not worth much. There's a ton of hours involved in a job like that plus the parts. I'd start looking for another car.

10,635

Thanks Munron, yes it is a lot of work. The 3.1 engine was very popular and is available all over the place. You can get a running engine for as little as $300. But the total labor to replace a rod bearing might not be worth it. Before trashing the car, I would pull both valve covers and make sure it isn't something easily fixable,such as no oil pressure, a stuck valve, bent pushrod or collapsed lifter. Just because 3 people say it "sounds like a bad rod" doesn't mean that's the problem. Dig a little. Good luck!

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