5th Aug 2001, 04:25
Big end problems usually produce no noise under acceleration at low revs, but will start to clatter at mid to high revs. If the noise seems to stop or lessen as you put your foot down, then its probably big ends. Main bearing noises are much harder to describe as they vary with engine design, but generally don't have the same rhythmic quality as big end problems. Just don't let anyone talk you into spending lots of money until you're sure the problem isn't some peripheral fault. I once heard a Fiat X1/9 engine that sounded like the big ends had gone, and I would have put money on it. Turned out to be the alty belt separating at its join and clipping a mounting! Beware...
1st Nov 2001, 09:26
I had a problem with my 200sx. The noise went away when I accelerated hard, went away when I came off the power, but that range in between putting on power and taking it off, ie maintaining the same speed, gave rise to a 'metallic' resonabce sound. This only happened above 2500 rpm.
The engine was a 'gold category recon' from Nissan, under warranty (for 2000 quid!!!) so I was worried as to its origin. I took it back to Nissan and convinced them that the noise WAS present. It turned out to be the heat shield of the exhaust. (on the down pipe) near the gearbox. It was about 2 turns of a screw driver to fix. It was free, under warranty, but it should cost peanuts.
See if you can get a mate to hold the revs at 3000 rpm, or whenever the noise becomes apparent, and get your head down, behind the front wheel, and see if it is coming from 'behind the engine' region.
Since then, no serious problems, but a hell of a lot of fun.