Last night, our WRX developed a knocking sound in the front of the car, presumably from the engine. It only happens at a partial throttle opening and between 3,000 and 4,200 RPM. If I floor it at those RPMs, it sounds and goes like normal. Same at lower RPM crusing. There is no knocking sound at idle. I changed the oil and filter on Saturday and it is still full and not leaking. Any theories?

can you reproduce the knock at will? Is it a deep hollow knock, or a tinny kind of knock?

USe a screw driver or wooden dowel as a stethoscope to try to trace the knock sound.

 

 

nipper

I was able to reproduce it yesterday, but when I started it up just now to drive four blocks to my house, I'm not sure it made the noise.

 

Not sure what the pitch of the sound is and won't have access to a stethiscope until Friday.

I was able to reproduce it yesterday, but when I started it up just now to drive four blocks to my house, I'm not sure it made the noise.

 

Not sure what the pitch of the sound is and won't have access to a stethiscope until Friday.

 

A long screwdriver or wooden dowel works just as well.

 

 

nipper

Are you sure it isn't piston slap?

Are you sure it isn't piston slap?

 

Piston slap goes away once the engine warms up, and not in that RPM range. Also a 2002 shouldnt have slap.

 

Unfortunitly in that RPM range, it may be something dreadful.

 

 

Thats why i want him to get a stethoscope test.

 

nipper

Can't really reproduce the sound while stationary, it seems that the noise is loudest under load. Also, the knock is not deep and hollow. It doesn't sound like rod knock that I've heard before.

After spending more time with the noise, I think that it is at most RPMs, can't tell down low though.

 

Any ideas? I'm thinking it might be a loose heat shield or something.

Dealer master tech took a ride with me a few months ago... Rod knock. We're just waiting until the engine lets go, or we get in a good enough place financially to take care of it.

The 2.0 wrx is well known for spun rod bearings. Sorry yours did it. You can get a used shortblock cheap, lots of these cars get wrecked and parted out or upgraded to the 2.5 shortblock.

I had no idea they were known for spinning rod bearings. Do you have a link to somewhere where I can read more about this phenomenon?

I had no idea they were known for spinning rod bearings. Do you have a link to somewhere where I can read more about this phenomenon?

 

 

I can't think of a specific link, but if you search for something like "spun rod bearing" on http://www.nasioc.com you'll get a lot of hits. I put an egine in one over the summer with a spun bearing.