Water pump bolts

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05-31-2019, 03:14 PM

ScubaSteveCA

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Water pump bolts

Just did another water pump, last was in october due to similar failure.

Bottom bolt sheared off with about 1/4" of threads sticking out of the block. Thats a new grade 8 bolt. Top bolt held but the casting cracked.
Is this a thing? Am I just unlucky (over torquing)?

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05-31-2019, 03:25 PM

oliver foster

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I have seen this before on a few motors.
Over torquing could easily be an issue as IIRC it is only 18 FT #s on that bolt.

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06-01-2019, 01:26 AM

thrashingcows

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As Oliver has said...Probably a tad too tight and then with the thermal expansion it is slowly break through the machining on the bolt?

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06-01-2019, 03:40 AM

ScubaSteveCA

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Thanks. Yeah figured both broken bolts had me in common. I'll keep em snug and add a little loctite for peace of mind.

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06-01-2019, 10:35 AM

j_martin

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Quote:

Originally Posted by ScubaSteveCA

Thanks. Yeah figured both broken bolts had me in common. I'll keep em snug and add a little loctite for peace of mind.

What's the big worry. Total outward pressure couldn't exceed a few hundred pounds. That force would be contained by 1/4 ft/lb of torque on 3/8 " bolts. A drop of LocTite blue is great insurance.