Engine Knocking sound 2003 Impala LS 3.8L

josh · Post by **josh** » Mon Feb 10, 2014 11:38 am

2001 Chevy Malibu v6 is making a hissing sound and running a little sluggish.

butch · Post by **butch** » Thu Feb 13, 2014 10:06 pm

A hissing sound is usually caused by a vacuum leak. That would only effect idle. It would not effect the engine under acceleration or when driving at a steady speed. A vacuum leak causes the engine to run lean so it runs rough too at idle.
You could try to spray some carb cleaner around the engine. If the spray gets into the vacuum leak, it would cause the engine speed to surge.

Be careful to stay away from ignition sources like spark plugs, plug wires, ignition coils etc because the cleaner is very flammable.

Some common areas on the 3400 V6 are the upper intake plenum gaskets, a leaking fuel injector O' ring or a hose near the throttle body.

brad · Post by **brad** » Tue Apr 08, 2014 2:51 pm

I have a 2006 ,pontiac torrent...when u start it up it has a loud knocking towards the pulley side near top of motor....as ut idles the noise quiets dow but is still a constant knock or tick...im thinking a busted piston skirt...harmonic balancer pulley....or a loose rocker...what do u think it could be???

butch · Post by **butch** » Tue May 13, 2014 10:57 pm

If the noise is near the top, then it would not be from a harmonic balancer or piston skirt. It could be from a rocker arm. That would make a noise more like a tapping, not a knock.

Do the basics first- check you oil level. Next would be to determine which side of the motor the noise is coming from- front or back. Then take off that valve cover and look for a loose rocker arm. Better yet, have a mechanic listen to it to diagnose it properly.

julien · Post by **julien** » Fri Aug 29, 2014 12:16 pm

When I shift the car from park to reverse, and into drive the engine will begin to make a knocking sound. So far I have got an oil change and replaced all motor mounts. Any help please? It goes away when I accelerate but returns once the car goes below 1RPM or come to a complete stop.

Terry · Post by **Terry** » Sun Sep 14, 2014 10:28 pm

An engine knocking noise can be several things. Worn out main bearings, rod bearings, piston ring or wrist pins, etc.

Since it seems to be related to shifting gears, you may have a cracked flywheel in your Chevy Impala. They can act strange and give a knocking noise that can be mistaken for an engine noise.

michael22 · Post by **michael22** » Fri Nov 28, 2014 8:08 am

i have oil in the radiator fluid...where would that come from

butch · Post by **butch** » Fri Dec 05, 2014 5:06 pm

What make, module and year vehicle are having this problem with?

ArentDualt · Post by **ArentDualt** » Sat Oct 26, 2019 7:38 am

Ok if i grab the pipe leading into the muffler and give it a shake i can hear a squeek coming from towards the front of the car. I can imagine if its vibrating fast that squeek could be the screech i hear. What would squeek like that? A hanger? Would spraying with wd 40 help?

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Engine Knocking sound 2003 Impala LS 3.8L

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Engine Knocking sound 2003 Impala LS 3.8L

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