by Howard
(Lake forest ca)

I have an almost new but hardly ever used Husky 0.8 scrum at 90psi max 125 psi. Model # 10228.

Wanted to get it up and running to sell it.

Everything was working fine until the oil fill cap kept blowing out of it? It’s not much of a cap. It slips into top above the oil level indicator. It looks like it’s made to blow out if the crank case gets to much pressure? Why am I getting so much pressure in the crank case below the piston?
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Well, Howard, simply, the typical causes of an oil fill cap blowing out are:

1) vent hole in cap is plugged

2) overfill of oil

3) a small amount of wear on the piston seal(s) is now a large amount of wear, allowing larger amounts of air to bypass the seals and pressurize the oil sump