What broke and how to fix it
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This is a scan of an article that originally appeared in Car Craft in September 1998. It is very informative, and deserves to be shared with the world. If you don't subscribe to Car Craft already, reading this should be incentive enough to go do it - now. Their articles and tech sections kick ass and they understand the whole "performance on a budget" thing better than any other car magazine out there.

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(Page 1)

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(Page 2)

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(Page3)

(My vote for the best item is the one of the hashed short block assembly on the bottom left of page 2. :-)

 

I've also collected a few pictures of failures in stuff I've owned or worked on.

This is what happens to a slant six rod after the engine is severely neglected for, oh, saw, 30+ years. Eventually the rod bearings wear out and seize up, then spin, then all sorts of bad stuff happens in rapid succession. This is from the rearmost cylinder. Note that the rod is bent in two different planes (aka, it's twisted two different ways), hit the piston skirt, and broke off completely at the big end (!). Once the big end came free, it also punched a hole in the side of the block. Sadly, I didn't take any pics of the window in the block.

SlantSix_ThrownRod1.jpg (2299412 bytes) SlantSix_ThrownRod2.jpg (1886367 bytes)

This is the oil pump drive rod out of a 1979 Ford 302. It was a "Shuck's Special" rebuild long block and ran OK for about a decade. One day there was a snap and then no oil pressure. The cause was this. Note the twisting in the rod - it was being torqued slowly until it finally gave up and snapped. Why'd it get like this? The oil pump used in the rebuilt engine was a cheap-o unit and had a sticky spot in the gears. My best guess is that the sticky spot caused a high torque to be placed on the oil pump drive rod once a rotation. Eventually, it couldn't stand the strain and started to twist along it's length to absorb the strain. Once it twisted enough, it was all over. When I tore down the engine, the oil pump had finally seized and wouldn't move. Once I took it apart, it started to move again, but had one sticky spot in the gears that I could barely turn by hand, even with the pump cover off. You'd think that because the pump gears are always bathed in oil, there'd be no problems. You'd be wrong. Luckily, the motor wasn't run long after oil pressure went away, so it's a rebuildable core. All this because someone wanted to save $10 on the oil pump when rebuilding the motor. Any guesses on why I rebuild my own motors and don't go with the super-cheap-o rebuild special at the auto parts store? This is one good reason why.

1979FordF100_302_OilPumpDrive_Broken.jpg (1763136 bytes)

 


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Page last updated 04/17/2011 04:13:36 PM