One year on..... Here we go again .....

[Dragrad]

Finally picked up the old engine bits today. Had a look at the crankshaft and with a metallurgist with me arrived at the following conclusion.... Its broken!!

Seriously though it does look as if there had been a weakness developing for a long time, maybe even from manufacture with a pitted area comprising nearly half the diameter of the shaft. So it was a case of when would it go as opposed to if. The other half was good clean shear

[JohnDotCom]

Yes definitely scrap!
What bits (if any) did you reuse from engine Andrew?

[Dragrad]

Originally Posted by JohnDotCom

Yes definitely scrap!
What bits (if any) did you reuse from engine Andrew?

Nearly all of them. Need to see what the garage left for me, I think that there are a couple of bits still at the garage. Will check on the 'morrow.

[Dragrad]

The area as shown in the pic is the pitted area showing the extent of the pitted fracture area. To the right is the shear, when it finally went.

On the left in the ringed area the metal was bashed around a bit when it broke. Same applies to the piston pic in the earlier post

So with only half of the required metal being used it's no wonder the darn thing snapped!!

Apologies on the pic quality - mobile phone!

[GreyGhost]

Thanks Andrew, nice to know I was 100% correct in my non technical diagnosis.

http://www.the75andztclub.co.uk/foru...&postcount=177

[JohnDotCom]

Looks like it could well have been faulty for some time? (I think GG came to that conclusion some time ago?)
Pictures to BMW would be interesting for a response.

[Dragrad]

Originally Posted by Grey Ghost

Thanks Andrew, nice to know I was 100% correct in my non technical diagnosis.

http://www.the75andztclub.co.uk/foru...&postcount=177

Indeed GG - your assumption was correct.

My mate reckoned it could have easily have come out of the factory in a weakened state (ie bad casting) and as time went on a fracture started and kept on growing as time and usage went on. Until there was more fracture than metal, so when I dropped into Sports mode and floored it...... The rest is history

Anyway one job for the weekend- put back the Pierburg MAF and Synergy 2

[Dragrad]

Originally Posted by JohnDotCom

Pictures to BMW would be interesting for a response.

Thinking about that.. any contact details?

[Jules]

Don't forget chaps that Andrew's engine was "modified" and therefore any power upgrades do in fact "eat into" the 10-15% SAFETY MARGIN that engine designers build into components.

Who knows how much longer it would have lasted in a "Standard" state of tune.
We will never know!

It still strains my ear to rev a CDT/i diesel above 4000 RPM & will do so even more now

[Dragrad]

Originally Posted by Jules

Don't forget chaps that Andrew's engine was "modified" and therefore any power upgrades do in fact "eat into" the 10-15% SAFETY MARGIN that engine designers build into components.

Who knows how much longer it would have lasted in a "Standard" state of tune.
We will never know!

It still strains my ear to rev a CDT diesel above 4000 RPM & will do so even more now

So is there a different crankshaft in the 131bhp engines? I thought that they were the same engines, just that some were detuned to 116bhp?

If they are the same, does your opening statement mean that the 135bhp engines might be more susceptible to crankshaft shearing?