A failure like this can only come from 1) bad design, 2) bad alignment or load on the bearing, 3) bad installation or 4) parts problem. 1) can be ruled out since this is a first for this failure, that leaves a choice of those other three. That shaft [42] is suspended by those two bearings, the front one is fixated axially, the rear is not - which makes sense as the aluminium of the engine will grow more than the shaft. But does the rear bearing run into a stop somewhere? And is there a way to check the shaft alignment? I would also be interested to know where the debris of the bearing went. The damage while bad now could have been worse. Hope for the owner that that head is recoverable. Nice pictures of the innards by the way, that crank looks the part.
Is this damage due to the failure or is this wear characteristic of mileage like on 348's How many miles on this motor?
It looks to me as if the chain guide damage is due to the failure. it would have created much more slack in the chain and the pull from the chain would force the gear upward, also toward that tensioner. but I am sure Bradan has seen more of these chain guides to definitely answer that. With such a low mileage, it could be that the bearing failed very early on in the cars life due to misalignment or another reason, and it simply went undetected till now.
I originally thought a bolt backed off the lower timing drive or cam gears but this was not the case. The last major was not the reason this engine failed.
Coupler is fine so is the pressure spring. I've seen them get stuck on other cars when something gets inside but this one was fine.
Honestly we will never know what exactly happened but a few people I respect agreed the bearing fell apart and a domino affect was a result. Parts just fail sometimes. You have to think in any manufactured part in the world from paper to Ferraris there is a certain percentage of failure or defect. It just happens.
It's from the chain slapping around during the failure. I've seen other 550 chain guides and all show basically no wear. On the 348 I only really see the early style pads wear out.
Is the item in the foreground pic in post #54 the coupler? It's not focused but looks cracked. I still feel that this was caused by resistance from the pump(s) and not a bearing simply falling apart on its own. If there was high resistance to drive the pump, the torque from the chain and sprocket would put very high side loads on that bearing which doesn't look like one that can handle high loads. it would pull the sprocket right up against the guide. Something would have to give, either the chain breaking or the coupler splitting or teeth shearing.
Great (if painful) thread. Thanks for sharing the details and responding to the questions posed. Philip
I understand your theory and it makes sense. I just have to disagree based off what we see later in the thread. More updates to come.
Yes keep in mind thats what we believed caused the failure. They F*ck you being to expensive and f*ck you being to cheap. Can't win either way.
Measuring out clearances for bearings. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Installing oil squirters. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Fitting crank bearings. The black coating is Teflon coating. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Laying the crank in and checking tolerances after assembly Image Unavailable, Please Login Image Unavailable, Please Login
Fitting pistons and rods. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login