[trond]

thanks a lot. Much appreciated. I am now in the process of splitting the block. From oil flow diagram all debris is pumped back to oil tank, via oil filter. Yet I found no magnetic debris in oil filter. The failed cams (same brand as previous failed cams) were both welded up cams. My rockers were all rebushed and reground by a reputed machine shop, and they all had perfect contact with the cam. I checked this especially. The failed rocker is marked DP1120.

Question on rocker arms; is the pad surface hardened or not ?

Originally Posted by MoreGAS

You might weigh all the rockers, and if all the same type, get an average and see how much cast iron material is missing by noting the weight differences. You didn't share which rockers you are starting with. That debris is floating in your engine as well as what is missing off the camshaft lobe, it is very abrasive, like cast iron lapping paste.
We very recently pulled apart a clients extremely costly engine, where someone chose aftermarket "trick"rockers(Brand remaining nameless) , DLC coatedpads ... well all the DLC coating wore off in no time at all, and the rockers began eating the cams, one rocker was missing 7 grams of material and the cam a whole bunch more not determined but it had to be welded-up to repair. Long story short , I had to advise we pull the engine apart with all that debris circulating in the oil . ALL rod bearing looked critically wounded and one was flopping in the rod cap with zero press or retention as all crush was gone and I don't know how it didn't over lap the other 1/2. If car was not towed to our shop, it would have tossed a rod straight out the top of the new case I am convinced. It also damaged the Nitriding on the crank on a couple journals.

Realize also that changing cam brands may do nothing for you as I believe from talking to the Porsche cam providers, all the billet blanks come from the same source. Billets are less prone to these issues vs. the hardwelds and regrinds, we never take that path any longer.

Who resurfaced you rockers and rebushed them? We have seen the new OEM rockers recently, not run parallel to the bushing bores, and not touch flat on the pads to lobes, Brand new. They also are senselessly heavy. Pass on those.

BeST

Kevin
GAS Motorsport