What is the knocking sound my 99 grand am is making

Asked by airforceguy21 Aug 09, 2013 at 08:43 AM about the 1999 Pontiac Grand Am 4 Dr SE Sedan

Question type: Maintenance & Repair

So I have a 99 grand am se v6 with
140 grand on it and its recently been
making a loud clicking/knocking
sound in the front of the car. When I
accelerate it goes away but when I'm
around 15-25 mph and decelerate is
when it's most noticeable. And it's
not soft it's loud. Like someone's
knocking on the window is what I
thought it was at one point when I
was driving haha. I can here it up to
about 35-40 mph then it kinda
dissipates or goes un-noticed. I
realize when I go fast around 50mph
and when I come back on base and
go slow again the sound isn't there
anymore and I don't know if that is
just a coincidence. I thought it might
be a bearing or ball joint or Somthing
in the knuckle but since it occurs
when I let off the gas and goes away
when I accelerate makes me think its
in the tranny?

8 Answers

"the front"....an auxilliary component such as power steering pump, power steering or an idler might do something like this~ check the auxilliary device belt~

2 people found this helpful.

if it's the engine sounds like a vacuum leak, PCV malfunction or vacuum lines fallen off (like on your fuel pressure regulator for example)~

177,545

It could be worm motor/transmission mounts allowing the CV joint on the axles to hit something. Get it on a lift and check out all the moving components in the front end.

1 people found this helpful.

could be the ac compressor cause i have the same issue and my uncle is a mechanic what he did was he took off the belt and the noise was still there cause he want to check to see if it was come from the engine but it wasn't when we took the belt off and i turn on the ac in the car the noise when away and when i turn it back off the noise came back.

I have a 2005 Pontiac Grand Prix and it has a loud noise like a knocking noise but only when I have it on drive while pressing on the brake can someone please help me out

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