jmca

Hi,

I managed to record the noise the other night in hope that someone on Scoobynet may know what it is or what is causing it or be abel to point me in a direction to solve and fix it.

Theres an odd noise from my car - a sort of muffled light knocking - I thought it was the downpipe but tightened around it and its still there.

Its there when cold and warm and goes away when you accelerate slightly and let it off.

I've done a good few searches and found posts on piston slap and big end problems would seem like and sound like and also some hints that would point it out.

I found the few posts about the piston slap sound file but thats not it from what I can hear.

If anyone can have a listen to see what they think - it would be greatly appreciated.

Download - engine sound sample - mp3 format


Regards

Johny.

Jolly Green Monster

iTrader: (4)

sounds like cambelt tensioner to me..

would expect the big end to increase as you revved it initially..

could be wrong mind.. is it a phase 2? (99 onwards)

Matt P

Where was the microphone? I would have said that unless the mic's at the front of the engine (in which case it might be the tensioner as JGM suggested) that sounds like some fairly unpleasant mechanical contact to me, and not piston slap either...

Having said that, I found a loose heatshield gave me similar symptoms when sat in the car, which surprised me as a heatshield is a relatively lightweight item, and the sound was quite deep.

Jolly Green Monster

iTrader: (4)

still think it would be quieter / no noise at idle if big end.. get noiser at higher rpm and increase with engine speed there after..

FB Tuning

iTrader: (30)

Easy to rule out cambelt tensioner by pulling off a belt cover and checking the belt tension. - You should really be able to hear the belt whirring if it's that loose

It's kind of difficult to pinpoint from a sound file. - It may be worth changing your oil and inspecting the oil for bits of brass coloured swarf - Ie. bearing shell!

Good luck!

Jolly Green Monster

iTrader: (4)

no so sure that the tensioner fails enough for you to notice the slack in the belt..

johnfelstead

sounds like the big ends to me.

willipdarling

If it is the big end the rattle will increase with engine speed. Def check oil first. Do an oil change also. Maybe add a heavier wieght oil, if that cures it then it is one of the bearings in the engine. If it doesnt it could be cams or something like that. Good luck

jmca

Hi All,

Thanks for all the input! Will have to investigate further.

Not very up on the whereabouts on investigating the cambelt tensioner.

Much appreciated.

Regards

Johny.

jurgen

any more info my mates does this noise too, doesnt run well either

easyrider

As said before-its hard to say exactly what it is on a sound file unless you hear it "in the flesh"-but it does sound like the big end to me.
What ever it is-i wouldnt be driving it without some serious investigation.

Gary

Turbotits

iTrader: (2)

Sounds daft,Have you checked all the plugs are tight?Sounds like its leaking compression.

ScoobyDawg

You may want to try removing all the belts (fan, aircon, power steering) and start the engine again, by removing the surrounding noises you should get a better idea other the noise origin. This is what my garage did, my knocking was from the left handside as you look at the engine from the front. I was told it was the usual impreza engine problem bearings probably No 2&3.
I would discribe the noise from my engine as a tapping which would on occasions get louder/firmer and then back to a tapping.

On stripdown the bearings on No2 were gone and it damaged the crank and conrod and No3 the bearings were worn down too.

Anyway nearly £1500 later I have managed to source new parts just waiting for the rebuild in the next 10 days. With a lighter/balanced rebiuld (sti9 crank, eagle rods, RA pistons, ect) I can't wait to see what it performs like when its run in. I'm hoping to photograph rebiuld for posting on projects. JDM WRX TypeR V-limited standard 300 bhp.

Da Dawg.

dieard

HI,

Just an idea, check your coloent level, i had a simialr noise, found out it was a head gasket which was knocking when the engine was pressuring, but did not affect the perfomnance of the car. check that the top coloent pipe (the one connected to the rad) is pressuring ok,

Im probably wrong, but just an idea.

Paul.