mikeg1981

Hi guys, have noticed recently a rattling sound coming from my engine. It sounds fine at idle but as i rev up it comes on about 1700 rpm and gets faster as i build up revs then starts to fizzle out as the revs get over 3000.
Its sometimes hard to hear from outside the car as its really loud car it is mostly noticable from inside. That is the only symptom really and I'm a bit concerned as some people have said it could be rod knock while someone suggested cam belt tensioner or idler.

The car is a 2002 bug eye wrx.

I just hope it isn't a rod bearing as i've heard its not a cheap fix

Fudgey

iTrader: (1)

no its not cheap.

rev it to 3k rpm and let of the throttle. if its the big ends it will knock as the engine slows down.

if it rattles while the revs are held it could be something like a vibrating heat shield, pulley etc.

good luck

Bristol98

Could also be piston slap or a sticky valve...

mikeg1981

Thanks for the info guys, i took it too see someone who knows a little bit and he says its the turbo, it does sound like its coming from the turbo more so when i listened through a screw driver! It is also a bit smokey if revved hard and has been a bit hesitant and jumpy on boost lately i just put that down to maybe needing a remap.

Does that sound right cause they wanna go ahead and fit a turbo they've got there for me.....

Fudgey

iTrader: (1)

Did they take the intake hose off and feel for play in the shaft?

should be able to see if the compressor wheel has been hitting the turbine houing, but that sounds more of a screech than a rattle.

if they diagnosed it as turbo, then it could well be bud.

id check all the heatshields on the exhaust around that area first tho so see if any are loose

mikeg1981

no they just listened and used a long screwdriver to listen into the turbine housing, i will go and see if i can check for play in the shaft, the heat sheilds have already been removed, thanks for your reply, i will keep you posted

mikeg1981

Been to see a few more knowledgeable people and they each conclude it is the dreaded 'rod knock' :-(
Gutted but I suppose it was always gonna happen sooner or later,

Thanks for your help.......

Fudgey

iTrader: (1)

watch this, skip to near the end when the chap starts it up

mikeg1981

Thanks for the vid, and to be fair it does sound very similar. You said earlier that it will knock as the revs drop back down. Mine does it when you hold on about 2500 and does get faster as te revs pick up then when the revs get high I can no longer hear it though it is a very noisy thing.....

Fudgey

iTrader: (1)

search youtube for impreza bottom end knock, its a loud thumping noise on deceleration, or if they are really shot on idle

so, when you get half an hour whip all the stuff off the front and do as matey has done lol to check

mikeg1981

it has been confirmed as big end bearing failure :-(

looks like its time for a rebuild then.........thanks for your help ;-)

Fudgey

iTrader: (1)

bugger!