M40 Big ends ?

[E30Mike]

Just looked a Hreg 318i tourer going cheap as owner recons it needs a new engine.

As soon as you start the engine you get a very loud knocking sound which dies away quite quickly to a resonable idle.

I asume that its probably the big end bearings but may be wrong.

Can they be renew from below having removed the sump or could it be anything else?

Any input would be greatly appreciated as an engine swap is not practical for me.

[Brianmoooore]

Sure it's not the hydraulic tappets at the top of the engine? Unusual to find one that doesn't knock. The unusual bit about this one is that it stops!
If this is what it is, it's perfectly harmless, if you can live with the noise.
Experimenting with different oil grades may help.

[E30Mike]

Probably used the wrong term as banging would probably be more appropriate than knocking but thanks for the info.