Cracked block cause?

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Freezerman

Freezerman

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This is a 5.9 I prepped for my truck. Replaced cam bearings, tested oil pressure with a drill. Installed engine, ran for 3 minutes, wouldn't build oil pressure, started instantly, ran smooth no higher than 1500 rpm. Stripped engine, cam bearings loose enough to pull out by hand. Yes all 3 center webs are cracked from top spider bolts all the way through the mains. Just trying to figure out what the hell could cause that?

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Here's another possibility. All three cracks are at the lifter retainer holes. Stress from those possibly being overtightened, or the wrong size bolts being forced in. This is one I have never seen before. That block is totally worthless now. I sure am sorry.
 
OK, yeah freezing didn't happen. I got it from a junkyard, supposedly 130k miles, hadn't been open before. After I installed the cam bearings, cam turned nice, 50psi oil with a drill. Had zero visible cracks.
 
Thanks, yeah at first I thought it maybe overtightened the spider bolts, but I torqued to 15 to 20 ft lbs. I'm glad you guys aren't sure either because it has me puzzled. I don't even care if it was something dumb I did, just be nice to know what caused it.
 
Dang brother! I’m real sorry!!

Hopefully you can find another block and just move everything over!!
 
Thanks, I fortunately had some cash saved and got a rebuilt shortblock with cam bearings installed already!! I will work on putting that in over the winter.
 
Freezerman said:
Thanks, yeah at first I thought it maybe overtightened the spider bolts, but I torqued to 15 to 20 ft lbs. I'm glad you guys aren't sure either because it has me puzzled. I don't even care if it was something dumb I did, just be nice to know what caused it.
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Well, keep this in mind. It might not have been something YOU did. In other words, it could have existed beforehand. Who the heck knows at this point? That's just depressing.
 
Freezerman said:
Thanks, I fortunately had some cash saved and got a rebuilt shortblock with cam bearings installed already!! I will work on putting that in over the winter.
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Good! Post up some pictures of your progress. At least you can put it behind you.
 
Thanks! Yeah it did suck. Had it all installed ready for some fall cruising...oh well.
 
did you strip the block bare to fit the cam bearings? if you didn't pull the crankshaft you almost certainly wouldn't see those cracks. as for it hadn't been frozen, it came from the junkyard with 130,000 miles so who knows it's history before that. maybe it was there as it had no oil pressure once warmed up?
neil.
 
Wrecking yards typically will replace bad parts, might be worth a check.
 
That is very interesting, and I would venture a guess that the only force strong enough to crack a (stock unmodified) block in that direction would be freezing. I don’t even think you could split one like that with the wrong cam bearing tool or being overly aggressive with one. Regardless, it sucks and it’s junk.
 
TT5.9mag said:
That is very interesting, and I would venture a guess that the only force strong enough to crack a (stock unmodified) block in that direction would be freezing. I don’t even think you could split one like that with the wrong cam bearing tool or being overly aggressive with one. Regardless, it sucks and it’s junk.
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Only problem is, there's nothing "to" freeze there. If it was submerged in coolant on those areas, then yeah, but it's not.
 
RustyRatRod said:
Only problem is, there's nothing "to" freeze there. If it was submerged in coolant on those areas, then yeah, but it's not.
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I agree. Hence the “very interesting” part. Someone would have to actually try to break it like that.
 
Possibly a major collision, could have contributed? But that's the first SBM I have ever seen cracked like that
 
Glad you guys are all stumped too. Long out of warranty period for the junkyard. It was dry when I got it, kept it in heated storage. No sign of cracks before. I guess always will be a mystery. I will take it to scrap next week with some other stuff, get a few bucks ..
 
replicaracer43 said:
Possibly a major collision, could have contributed? But that's the first SBM I have ever seen cracked like that
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My money is on a strong collision directly into the balancer, or maybe even has been used in a youtuber's truck involved in some sort of jump competition. Just curious, what did the bearing shells and crank look like? Any signs of a bent crank?
 
No physical damage that i saw. Although there was probably a reason the truck with engine had been in the junkyard...accident maybe
 
That is a vibration crack from spinning up a severe out of balance motor. Seen it on other engines that came in. That engine probably had a internally balanced converter in the past and was abused. We just got a fresh 440 race engine in that had an off center torque converter pump hub welded on. The engine was fresh and lasted to week ends . Same crack up through the center. Big blocks and 360's are weak. one reason the Hemis had side bolt mains. We offer that application to all BB customers.

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Interesting, it must have already had some damage. I never had above 2k and less than 5 minutes.
 
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