Is the oil sight also the oil drain?

by Sonny
(Los Angeles, CA)

On the Central Pneumatic 67501 Air Compressor – is the oil sight also the oil drain?

Central Pneumatic model 67501 Photo:

Central Pneumatic model 67501 Photo:


Are you talking about whether or not the sight glass is the drain? Not normally Sonny, though there are some brands that require that. Not typical for Central Pneumatic, though.

Typically the drain plug is at the bottom of the sump, often below the sight glass.

I looked at a couple of photos of this compressor but neither showed a clear shot of the pump end.

I have uploaded a photo of the compressor with a couple of annotations showing where the oil fill and oil drains are typically.

The oil goes in via the fill tube which is located over the sight glass. Usually the oil drains from a plug installed at the bottom of the oil sump and often in line with and below the sight glass.

To drain the oil you have to unscrew the plug.


Where do you add oil? Compressor is making a loud noise.

by Tom
(Agua Dulce, TX)

Lost the instruction manual. Think it needs oil. Where do you add it?


Hi Tom. Bit hard to figure where to add oil to your Central Pneumatic air compressor since you haven’t included model or HP, and there are many, many Central Pneumatic air compressors on the market.

First of, make sure your compressor model is oil lubed?

If it is, there should be a fill tube or oil fill cap near the bottom of, or adjacent to, the pump housing, and usually, below that, there will be a nut or bolt that can be removed to drain the oil sump.

The loud noise, if new, would suggest to me that you may be developing a vale problem, or that an internal gasket may have let go.

The model number and photo or two of your air compressor would sure help me help you too.



How do I properly use the oil dipstick?

How do I properly use the dipstick on my central pneumatic compressor?

I have Central Pneumatic Compressor but am unsure if I am supposed to screw in the dip stick all the way to check the oil level or just put it in until it stop without screwing it in. There is about 3/8″ of threads so it makes a big difference. The oil is so clear I can’t tell anything from the site glass.


Good question. I’ve never read anything about this in any air compressor manual, but I can tell you that I screw the dipstick in all the way to take an oil level reading on my air compressor.

To me, not doing so would be like NOT putting the car dipstick all the way into the car engine to get a reading on that oil level.

Since the air compressor is meant to operated with the oil dipstick threaded completely into the hole, I suspect it is a safe bet to do the same when testing your compressor oil level.