What is making this really bad knock on my 2003 Grand Am G.T.?

Question

I all the suddon one day i started my car and it has this god awful knock but it stops once my car gets running for like 2 min or so i have know idea what it is. Lifters? Beats the Heck Out of me and how much will it cost to fix. Its got the ram air 3.4 L

Answer 1

I had a similar problem in the past, but with a Ford. All I can remember is every time I stopped it got louder and louder. Finally I took it in and it cost over $800 because the part was hard to get to.

Answer 2

One persons knock is anothers tap, so I would need to actually hear the "knock" to be able to tell you, and that is exactly what a mechanic will tell you. So, before you throw a rod or chew up a camshaft, take it to a shop and get an estimate. You will not get a good estimate over the internet. Sorry, it just does not work that way in this case.

Answer 3

Knock is usually caused by timing or fuel issues. It could be bad fuel, or the timing. If it's a persistent problem (i.e. lasts through many tanks of gas) it could be a knock or O2 sensor. It sounds like it goes away once the engine is at operating temperature. Which would indicate to me that it is an O2 sensor. But since it does this for minutes, I think the knock sensor may be bad too. If it was operating properly the ECU would retard the timing to quell the knock a lot faster than 2 minutes.

Answer 4

You have got to be more specific. Is it a heavy, low knock, indicating a rod bearing going south? Or is it a ticking sound, frequent, and higher up on the engine, indicating a cam/valve issue? I can't tell you without hearing it.

Answer 5

you may have worn crank bearings, if you keep driving it that way, your crankshaft can lock up and break on you.