GTS liners cracked, not pretty
11-16-2012, 09:58 PM
#31
Former Sponsor
I agree.
I have seen similar damage on other motors when foreign objects had entered the combustion chamber. It appears to me that the only explanation here is that the piston wasn't able to compress all of that build up in this event. Something had to give. I would follow GB's suggestion to closely look at the rods if you plan on keeping the rotating assembly for use in a different block.
I have seen similar damage on other motors when foreign objects had entered the combustion chamber. It appears to me that the only explanation here is that the piston wasn't able to compress all of that build up in this event. Something had to give. I would follow GB's suggestion to closely look at the rods if you plan on keeping the rotating assembly for use in a different block.
11-16-2012, 10:02 PM
#32
Former Sponsor
Maybe all the carbon fell off when the head was taken off ... and that's just a red herring. You can still see it hanging precariously on in one bore, and it wouldn't take much to dislodge it.
Considering the state of the gasket I think hydrolock is still a possibility ... it wouldn't take much. The lack of coolant in the bore after the 'event' and after stripdown could be explained by seepage past the rings or out the cracks.
Considering the state of the gasket I think hydrolock is still a possibility ... it wouldn't take much. The lack of coolant in the bore after the 'event' and after stripdown could be explained by seepage past the rings or out the cracks.
11-16-2012, 10:05 PM
#33
Rennlist Member
My thoughts are that I'd prefer the rod to compromise before the corresponding journal. I guess that is a positive way to look at this situation. Sometimes, though, it can be more like a catch 22 than one or the other. Not likely that the crank was harmed IMO.
11-16-2012, 10:31 PM
#34
Former Sponsor
The 928 crankshafts are so robust, it is very rare to see one damaged, unless there is a thrust bearing failure or a rod bearing failure. A little thing like the piston being stopped BTC, the cylinder breaking, and the rod bending wouldn't even begin to hurt one of those "truck" crankshafts.
11-16-2012, 11:54 PM
#35
Addict
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Got a block like that hanging inverted in my garage..powder coated in bright silver. The powder coat nearly covered up the crack in the cylinder. Thats how i would make it right.
11-17-2012, 05:38 AM
#36
Three Wheelin'
I started with a block like that for my 7.0 engine. That crack probably extends all the way down to the 'floor' of the water area even if you can't see it.
I can't imagine anyone being confident in a weld repair of that. It would be much more reassuring to drive a block with different numbers than wondering how the weld was holding up and wheter other cylinders are next.
I can't imagine anyone being confident in a weld repair of that. It would be much more reassuring to drive a block with different numbers than wondering how the weld was holding up and wheter other cylinders are next.
11-17-2012, 08:21 AM
#37
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The 928 crankshafts are so robust, it is very rare to see one damaged, unless there is a thrust bearing failure or a rod bearing failure. A little thing like the piston being stopped BTC, the cylinder breaking, and the rod bending wouldn't even begin to hurt one of those "truck" crankshafts.
