Knocking noise when accelerating,1996 Pontiac Grand Am.?

Question

Only when accelerating,as soon as I reach desired speed,the knocking quites.No matter what speed I'm going.

Answer 1

I had a 64 Ford it had a Ltd engine and tranmisson but it was doing the same thing.I am one of those people who say don't fix it if it ain't broke and my truck was still running so I kept going.Well I tried going from Flordia to Tennessee and my flywheel broke in Nashville.It sounds to me that your problem is the flywheel.When I pulled my tranmisson back away from the block I was amazed.The flywheel had broke in a jagged circle all the way around the bolts.I pulled it off in 2 pieces.Good luck I hope this helps.

Answer 2

It sounds like you are talking about spark knock.After mileage gets to a certain amount carbon builds up in the combustion chamber and make the cylinder smaller raising the compression ratio.One way to confirm this is to put a higher grade of gasoline into your vehicle and see if that stops the noise.If it does than carbon buildup causing spark knock is the problem.Depending on how sever the problem is the fix can be as easy as a can of a parts store chemical that is added to the gasoline that will break up the carbon buildup or if the buildup is severe then the cylinder heads and the top of the engine has to come off and the carbon removed by a machine shop.However if putting better fuel into the car does not stop the knocking then you have to have the vehicles ignition system checked to see if possibly that the timing has gotten advanced too far and that would have to be fixed.Sometimes the timing chain stretches and jumps it's correct position which will advance the timing which can cause spark knock.

Answer 3

This sounds like you are experincing preignition and your egr valve is at falt. If you are planning to do it your self, this is where I would start. it is accesable from under the hood and only bolted to the intake with two bolts and your year car with a single electrical plug. The egr helps lower combustion temps thus eleminating preignition. let me know how it turns out.

Answer 4

I have a '96 also, I've never had this happen. I'd go first with checking the basics, like oil, fuel filter/fuel pump, or just take it in somewhere where you can get a cheap inspection if you don't want to do it yourself...

Answer 5

It could be rod knock (bad wrist pin or crank bearing) -- very expensive.

Or it could be just preignition, which could be solved by switching to intermediate grade or high octane gasoline. If you are already using premium, you could be in trouble.

Good luck. I hope it's just the gas.

Answer 6

I've been told that's a sign of cheap gas. Don't know if it's true or not, but it could mean that water had leaked into the gas tank at the gas station.

Answer 7

Sounds to me like a main berring ,DON'T BEAT ON IT,or you could throw a rod.