Engine failure - what is unrepairable

Poker2009 · 24 Nov 2017

mistake

Poker2009 · 24 Nov 2017

bazhart said:
Crankshafts used to be case hardened deep enough to re-grind smaller - but the process was time consuming. Modern production uses a nitriding process just to harden a thin top skin and this costs less but if you re-grind you go through the hardness and they will not last as long.

You can re-nitride harden them but that is also costly because you need to regrind first - then allow for the growth in diameter that occurs during Nitriding (requiring some experimentation) then polishing the nitride surface afterwards.

We have done this and the results have lasted several years - but it is not much less expensive than a new crankshaft and the teeth that the IMS chain runs on are usually worn, many cranks have a slight bend in them already and so it is a bit of a hit and miss process.

To make it viable you would probably need a lot of old crankshafts and after the process may well have to reject and scrap a few that still didn't come up to the quality required.

When we recently noticed an increase in the number of engines that have covered 80 to 100K failing through crankshaft failure, this is why we have advised owners to seriously consider a pre-emptive rebuild while their crankshaft is still OK. We took a lot of criticism and the usual accusations of scare mongering - but we said that tile will show our advice is right.

With cylinders going oval, pistons losing coatings, chains and guides wearing and crankshaft shells wearing - it can make sense to have a rebuild before the crankshaft fails - if you intend to keep the car - and of course - can afford it.

We hope that as our "oversized engines" become more widely publicised - this may also make a difference to those struggling with the choices when their engine seems to still be running OK.

These brilliant cars will IMHO bee among those valued in the future and having a reliable engine adds to their value and desirability.

Baz

Just so I understand, do you change the worn out crankshaft shells, which in turn would save the expensive crankshaft, if done in time?

Would it have to be re-done in another 80-100k miles, or do you strengthen it somehow?

wasz · 24 Nov 2017

maldren said:
I asked him about the exchange and he told me that the engines are brand new and Porsche only stipulate that the damage is inside-out not outside-in. In other words, if you crash your car and wreck the engine it is not covered but if, for example the IMS fails and the engine is destroyed, that is covered.

Thats interesting, but seems counter to Stoo.C above.

Stoo.C did yours fail internally or did you have some outside factor?

Engine failure - what is unrepairable

Poker2009

Suzuka

Poker2009

Suzuka

wasz

Paul Ricard

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