Hello,
I have a classic RB5 which has developed a strange noise, I was on my way home yesterday when a loud knocking noise started coming from under the bonnet, at first i thought my exhaust had burst or fallen off as the knocking was in time with the burble but once I got home I popped the bonnet and found that the sound is coming from behind the cam belt cover I think. It sounds like someone hitting plastic with a hammer. I recently changed the cam belt and tensioner so I wonded if something had come loose, I took of the N/S part of the cover to get a look as it seemed to be coming from behind there but I couldn't see anything wrong, the belt and tensioner seem fine and when i started it again the noise was still there.
There is no signs of smoke from the car and it was running fine apart from the noise, it was pulling and boosting ok when i was driving it home.
It doesn't really sound like something in the engine (i dont think) but i'm a bit stumped as to what it could be.
Any one got any ideas ?
Thanks
Martyn

 

Sounds like the dreaded big end, drain the oil through a fine clean cloth, if you have shards of copper in the oil, it's bottom end re-build time.