[quote=Crackshot;2843357]Less than 1% with 53 blocks had the cracking problems. Mainly because people did not warm up their trucks before towing. (Something that should be done anyway)
The 1% figure was an estimate Cummins put out. Actually a person in customer service told me 1-2% but that was what was fixed on warranty. Many cracked after the warranty and wouldn't show in the figure because Cummins didn't have to deal with it, so a better guess might be 5-10%. You must remember also that two foundries in Brazil cast these blocks, according to Cummins, but one had no problems because their castings were 11mm thick in the area that cracks whereas the others were 5-6mm hence the weakness. But even there not all the thin ones cracked either. I wouldn't say that it isn't a good idea to warm these motors up before putting big loads on them but they shouldn't crack with the load either. You may feel comfortable buying any 53 block engine but given a choice I wouldn't. I would also add that I put over 100k on my 53 block without cracking but I never had confidence in it either.