by Bob
(Hobe Sound, FL)

The plastic combo oil filler/dipstick with crankcase breather on my little 2.5 gallon Harbor Freight compressor was cracked and falling apart.

I put a collar and epoxied a reinforcing cap on it, then I re-drilled a new breather hole to intersect with the old.

Central Pneumatic 3 gallon air compressor

Central Pneumatic 3 gallon air compressor

I ran the compressor, later noticing a growing puddle of oil underneath.

I can’t see where from just yet. In re-examining the repaired cap (since that was the last thing “fixed”) it seems possible that the new breather hole was inadequate or blocked by drill swarf. If that is the case is it likely that oil leak came from the crankcase oil seals due to a build up of crankcase pressure?

If so, are these seals easily replaced or should I just get myself a new $89.00 compressor?

This compressor has not seen much use and should have lots of life left – normally.


Bob, “easy” is in the eye of the doer. What’s easy for you might be hard for another, and since I don’t know your capabilities, I don’t know if re & re seals would be easy for you or not.

Certainly time consuming, and you will make quite a mess as you pull the sump apart to find, and replace seals.

Your premise about seals may not be correct. While there is some migration of air into the sump past a leaking cylinder seal, I understand that the vent hole is there to allow outside air into the oil sump to replace oil that has been “used” and stopping a vacuum from being formed.

You will have a time trying to get Harbor Freight air compressor parts too.

However, if I had the time, and the workshop, then I would certainly tear it down if for no other reason that to see what’s what.

Odd that the oil fill dipstick cap cracked on an air compressor with so little use as yours did???

$89.00 compressor, when we buy one of these, we get exactly the value we paid for.

I could not find any compressor of 2.5 gallon tank size, though I did find a 3 gallon shown in the photo. For what it’s worth, in early 2019 this one’s selling for $60.



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