Broken rod in a 360

[Saltwater Cowboy]

I picked up a 360 from a friend that was siezed. I pulled the pan off and found a broken rod (pass side rear cylinder) and spun rod bearings in the back two cylinders. I am thinking of going threw this motor and putting it in my Jeep but am curious as to what happened. This block has the lifter valley oil line mod and had good oil pres. up until it seized. It has maybe 10-20k of mileage but was making a knocking noise prior to the failure. I am thinking that it spun the rod bearing and then that weakened the rod. Is this common on these motors or could this be an assembly problem. What other things should I be looking for? The bottom of the cylinder has a small chunk missing now but it stays well away from the rings so I am thinking it should be ok.

[ironman_gq]

probably starved for oil. if the oil line wasnt done right they can reduce flow to the back of the motor by partilly blocking the oil passage. I think that it has been determined that with some of the new parts available here that a valley line is not needed and could cause more problems than it solves.

[Saltwater Cowboy]

What should I look for to make sure that oil line was done right?

[tufcj]

Remove the factory plugs in the oil passages. Shine a light down them and make sure the valley line fittings don't extend into the oil passages. When replacing the factory plugs, make sure they don't do in too deep also, especially the ones behind the cam gear.

If you're going to rebuild, be VERY careful to clear all the passages of metal shavings. Open everything up, pressure wash and brush all the passages.

Bob
tufcj

[AMX69PHATTY]

Could be what broke the Rod, after it spins a rod bearing, usually the one in the cap doubles over onto the one in the rod, so now on the rod cap side there is metal to metal contact between the cap and the crank rod journal, and if one continues to run the engine, eventually the rod cap offset grinds the crank journal enough to allow the piston to hit the head, and whamo, busted piston and possibly a broken rod.

[Saltwater Cowboy]

The piston looks like new. It snaped the rod where the rod meets the crank, the cap is still in one piece. I was talking to the guy I bought it off of and he told me that it was overheated a couple of times. He forgot to turn his electric fans on. It was also burning oil and I think it got low on oil and he went down a steep hill and the oil went to the front of the pan and lost suction on the pick up and fried the bearing and then broke the rod. The rest of the motor looks good. Thanks for all the info guys, it is appreciated.

[ironman_gq]

rod probably welded itself to the crank or piston pin. had that happen to a go kart but that was just a little 5hp briggs engine. still made a pretty spectacular mess in the crankcase.