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snapped crank

Posted: Tue Oct 04, 2005 9:42 pm
by scrappy
My beretta broke the crank @ a rod journal. It was completely stock a that time. it did it while backing out of a parking spot and putting it in drive(I was told, brother was driving it). It didn't lock up, just knock real bad. It ran for about 1.5-2 hrs like that while I was trying to figure out what was wrong. it didn't lock up until I reved it to 3 K. rpms and locked after i released the throttle. What can cause the crank to break like that? It was relatively low miles, it still has crosshatching in the cylinders.

snapped crank

Posted: Wed Oct 05, 2005 12:36 am
by I-GOT-BOOST
Read your post. I think you answered your own question.

snapped crank

Posted: Wed Oct 05, 2005 12:11 pm
by Ryan from Ohio
Take it out and have a look at it.

How many miles were on the motor?

Its probably a defect in the product itself. It may have got Heat Cracks during the grinding process. Likewise the material could of had a crack in it from handling or from the actualy forging/cast piece. Lastly porosity. If it had Porosity you should be able to see it with the naked eye or a magnifying glass.

At any rate it should of been caught @ Magnaflux at the factory... Well if any of the above is true.

Im not sure if thats a heat treated crank or not... Or what material it is...

All looking at it from the component point of view. Im sure it could be other mechanical matters... Not exactly easy to snap a crank- well in a motor. I see a few snapped ones here at the shop though  

snapped crank

Posted: Wed Oct 05, 2005 5:41 pm
by scrappy
The motor broke it when it started knocking, it just didn't finally lock up until I revved it up. When I bought the car , it had a blown head gasket that I fixed. I drove it for about 6mo. before it died so I don't know how many miles but I doubt that it had 30K. on it

snapped crank

Posted: Wed Oct 05, 2005 9:01 pm
by wicked-irocz
my guess is oil starvation to that rod bearing caused by a plugged oil passage in the crank.

snapped crank

Posted: Wed Oct 05, 2005 11:34 pm
by Guest
I've heard of a few 60 degree V6s doing this...