Nasty knocking/tapping noise

[badrover]

I recently removed my v8 engine to replace the rear crank rope oil seal. I removed the big end shells, main bearing caps and crank to do the job properly. There were some signs of wear on the bearings but the engine ran a treat so I didn't replace anything, except the rope seal. It's now back in the car, oil pump primed and I've started it for the first time today. Disappointingly there is a very nasty and audible knocking/tapping noise now that rises with the revs. I shut it down after 30 seconds or so. Having removed the sump, there are small fragments of metal in the fresh oil. What have I done wrong? It ran an treat beforehand! The only diagnosis I've managed to do so far is that there seems to be a little movement (maybe only 0.5mm) on each big end pairing. I guess this is not good! Is it crank regrind, new main and big end bearing time?

 

[harveyp6]

If the noise appeared after you worked on it, then it will be something you've done, and if it is a really heavy knock (big end) then once they're that noisy then generally it will damage the crank.

All you can do is dismantle it all again and the damage should be obvious, hopefully leading you to find the cause.