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  #16  
Old 05-26-2005, 11:07 PM
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dan_j_b dan_j_b is offline
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Yeah I know I got the parts all where they came from, but I musta missed a nut or something when I torqued it all down. the counterweight parts of the crank around where the rod was are pretty scraped up. more pics to come.
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  #17  
Old 05-27-2005, 02:59 AM
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Quote:
Originally Posted by dan_j_b
I took the motor apart today and I think I found the source of the noise. My guess is I either didn't get all the main caps tight enough or a wrist pin clip came out. Luckily, although the spark plug was smashed flat, the valves and head otherwise looks perfect. So I guess I am shopping around for a short block assembly. Anyone have one in the Sioux Falls area?
I reckon you got it on the first guess, except I think you meant 'rod caps.' In the pictures, the cap bolt on the right looks fatigued where it broke. The threads on the left cap bolt are a bit chewed up, but no apparent stress marks. On the rod's crank bearing race, both sides of the race are broken off, but one side looks like a fatigue failure while the other side appears to be yield failure.

I speculate that one nut worked it's way off the [left] rod bolt. The [right] side of the bearing race held on as long as it could, flexing back and forth, which caused the wear marks on the threads of the [left] rod bolt which no longer had a nut to stop movement. The [right] rod bolt and [right] half of the bearing race flexed until the metal fatigued and failed, leaving the clean break characteristic of a brittle alloy. The bearing race of the rod, being aluminum, probably failed right away, but was held together by the rod bolt until it also failed in the only place it could flex: where the bearing race had previously failed. When the [right] side failed, the cap simply slid off the [left] bolt, which appears to be pressed in, and functions more like a stud. In this scenario, the other half of the broken bearing race was sheared off on the next revolution of the crankshaft as the remaining cap struck the stationary rod, still protruding from the bottom of the cylinder. This explains the bent rod and deep scarring of the [left] failure point. Alternatively, the cap did not simply slide off, but rather came off in a twisting motion, causing the [left] half of the bearing race to fail instantly. The bent rod and scarring would have happened on subsequent passes of the crankshaft.

...at least that's what I think happened. Did you see anything that reinforces or diminishes my theory?

Anyway, sorry about the luck. Sometimes dotting your T's and crossing your I's can be as dramatic as throwing a monkey wrench into the works.
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  #18  
Old 05-28-2005, 11:06 AM
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Yeah that sounds like a good theory to me. I'll let the real experts deliberate over the exact details. I'm just going to put that whole thing behind me and swap in a diffrent used shortblock. Yeah I meant rod caps, not main caps. It looks like the shape of the piston saved the head. It smashed the spark plug flat, but doesn't look like it touched the valves. I'll have the head checked out by a machine shop before I reuse it, but I think it looks fine.
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  #19  
Old 06-14-2005, 10:06 PM
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Carnage continued...

I took the engine all the way apart and got some good shots of the insides. I also found out that the other rear piston broke and bent the rod.

I am getting a whole used engine so I will have everything from this engine minus the block and a few rods and pistons left over so let me know if you need anything. After I get the other engine in the car and running, I will start selling some of theseextra parts, but feel free to PM me with questions for the time being

Dan
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  #20  
Old 06-18-2005, 03:02 AM
NeedForSpeed NeedForSpeed is offline
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That's some major trauma for sure. Thanks for the pictures!

Quote:
Originally Posted by dan_j_b
I took the engine all the way apart and got some good shots of the insides. I also found out that the other rear piston broke and bent the rod.

I am getting a whole used engine so I will have everything from this engine minus the block and a few rods and pistons left over so let me know if you need anything. After I get the other engine in the car and running, I will start selling some of theseextra parts, but feel free to PM me with questions for the time being

Dan
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  #21  
Old 06-19-2005, 01:43 PM
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TomsSVX TomsSVX is offline
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Hey Dan, I am thinking of rebuilding one of my extra motors. I wanted to know if you were doing a full rebuild or just something minor. I need to find main and rod bearing kits, along with some other parts. I know I can find them on Subaruparts.com but for the prices of the parts, I can pick up 3 junkyard engines... That doesn't even factor in the machine shop work i need to get done. Anyway if u could pm if u have any info on aftermarket parts, that would be great

Tom
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