I've had the engine for 2 years now, bought second hand with paperwork to prove its rebuild. Since day one its had piston slap, which doesn't concern me, but its also got a noise when revving the engine freely with no load. Its pretty much a singular cracking noise around 2k when letting off, audible under the bonnet only.

I've had bearing/crank failure on other cars so I'm used to the sound. Its normally more than just a single knock though. For it to be like this and not have let go for 2 years would suggest its not the crank/bearings.

Any thoughts?

Standard v3 sti engine.

 

Remove the fanbelt and check the crank pulley. They are a two-piece unit with a rubber core separating the two bits. the rubber can go hard and disintegrate, making the two bits move. Mine did, Harvey replaced it with an alloy one.

 

Sounds like a plan. I suppose it's a case of trial and error.I did wonder about the timing belt tensioner too. Its the early type on my v3 engine.

Thanks for the advice!!

 

I thought mine was going, until Harve diagnosed it.

 

i think i know.
the piston slapped the crank.
the crank bit the piston in return.
and then there was a fall out in which the cams got involved and accused the crank of being a father.
dna test on jeremy kyle proved that the cam nor the crank were the dad and so the pistons claimed lots of benefits and smoked weed.
then the pistons were arrested for a robbery by the ecu police for being armed with ARP bolts and intent on power.
then the injectors got involved and employed the fuel pump to kill them all.
the fuel pump (who we will call Walbro) starved the pistons to death and then the government was overpowered by the td05 (goes by the name of gooshla)
now im being arrested by the fmic who have information on me using jubilee clips.
get me out of here bbbrrrlllleeeeeeeeeee

 

Now that's funny

 

Warm it up and drop the oil through some clean white cloth, if the bearings are worn enough to make a noise there will be plenty of evidence in the oil.

 

Update. No issue other than not tightening the pitch mount bolt on the bulk head when fitting the engine. I'm surprised the bolt was still there as it was held in by a thread, literally.