Another little trick on copper sealing washers

junkyardhero said

great idea, let's hit a bolt that's hollow. just fantastic. I foresee a whole bunch of core returns with broke off banjo bolts and tons of customer pay for R&R broken bolt, flush and bleed system.

If a leak is that much of a concern there's washers with rubber impregnated in them that work wonderfully.

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The impact is in tension, not shear. Hollow or not won't matter.

A quick rap will put more load on the washer and ensure a good imprint. Hitting the same load with axial bolt tension risks the bolt more than a quick pop with a hammer..

The only real risk comes from hitting it without some adequate preload on the fastener to take the slop out of the threads. But with a couple grunts in the wrench, a pop on the head of the bolt won't hurt a thing. Knuckle draggers are more likely to hit it off center and screw up the hex, or miss and hit their fingers..