I think the day ive been dreading may of came. I started up my 97 wrx classic today and to start with it sounded fine, after 2-3 minutes the engine started knocking is this going to mean the big end or could i be lucky and it be something more simple?

 

Doesn't sounds good, but could well be something more simple. Get it to a trusted specialist, the key word being trusted, as many companies will happily charge you a couple of thousand to do a rebuild you don't need.

Have a word with David at Api if you can.

Ns04

 

Its strange though because i went for a drive in it came back it sounded ok. Surely the big end would knock all the time wouldnt it?

 

Could be piston slap, there is a sound file on here if you do a search. Still best to get a reputable Ear to have a listen & make certain, Piston Slap does lesson or even disappera once the engine is hot.
Dean

 

Would piston slap knock loudly though? I thought that was more of a tap and this knock is new

 

Another possibility is the cambelt tensioner?
JohnD

 

funny you should say that,cos tonite after fitting the cambelt on a legacy turbo ive just put in a vw camper we noticed a slight tapping and held a plastic ratchet handle against the cambelt tensioner pully the noise noticibly went a lot quieter

 

Piston slap can be & is normally loud especially from cold, More of a Grrrr Donk

Look & Listen here (No it's not a road safety campaign!!)

https://www.scoobynet.com/general-te...ound-file.html

 

You wouldn'lt get piston slap starting 2-3 minutes after starting the engine. It would be there from turn over (assuming the engine is cold) and then gradually die off as the engine warms up.

 

Due to the different expansion rates of the piston and liner, it is possible that slap could be more noticable after the engine has been running for a short period than at cold start-up. I agree that 2-3 mins. is a fair time before it's heard, though.

JohnD

 

Thanks for all your advice. It turned out that the crank pulley was just lose and only need tightning so lucky escape this time