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its8up t1_ja90xuh wrote

Edit for all the people downvoting:

Excessive air coming from the oil fill is an obvious sign of a problem with the rings, cylinder, piston, or valves. My guess is broken rings or a fault with the intake valve. Such a defect will also prevent a compressor from intaking as much air as one that does not have such a defect, thus explaining why the air leak is deemed excessive yet assumed to not be the problem.

My bad for being tired and not breaking it down properly the first time. I get that most people lack the mechanical understanding necessary to have reached this obvious conclusion, especially considering how scattered my earlier trail of bread crumbs was.

Feel free to get back to downvoting. I also have a comment below for your downvoting enjoyment.

Original reply:

Get back on that original note, pal. Compressors work like internal combustion engines in that they have a crank shaft, pistons, and rings. Some leak through the rings is acceptable, but bear in mind that any air coming out of the oil cap is air not making it into the tank. Ergo, a lot of air coming out of the oil cap equates to a lot of leak. This is to be expected of a worn out unit, not a new one.

Granted, I do not know @op's gauge of what comprises a lot of air leaking out.


DCOutlaw620 t1_jab7pnd wrote

You took my downvote at pal.


its8up t1_jabe7uq wrote

No worries, pal. You choose to be a douchebag, and I totally respect that.


SatanLifeProTips t1_jaamgzm wrote

I don’t know why this got downvoted, this is actually a really solid answer for cheap piston compressors. Ring blowby and a lot of pressure behind the oil cap or air / oil shooting out the breather is a sure sign of ring failure. You check used car engines like this too.

You can also check the valves to make sure they are sealing properly.

Ex car mechanic, current industrial mechanic here. I work with big boy compressors.