Hey! This site is reader-supported and we earn commissions if you purchase products from retailers after clicking on a link from our site.
by Richard Swenson
(Wareham, MA USA)
I am new to compressors. I just purchased a used 30 gallon/5.5 hp compressor (craftsman compressor 919.165310). It is working fine, but I notice that it will lose all it’s pressure if shutoff and left alone for about 2 days.

Is this normal? obviously there is a very small leak(s), but i don’t know if this should be expected or something i should address.
Any input would be greatly appreciated. Thanks.
_______________
Compressor hold it’s pressure
In theory, once the compressed air gets to the tank, it should remain in the tank indefinitely.
The reality is that the tank check valve may leak a bit, a fitting on the discharge line may leak a bit, if the hose is plugged into the discharge coupler and whatever it’s attached too leaks a bit, over time, the tank pressure will dissipate.
That yours loses all air pressure in two days suggests a bit more than a small leak, and with the tank empty of air and the power off, I would pull the tank check valve and check it / clean it to see if that resolved the leak.
_________________
Thanks…
Thank you for the help. i found the leak, and the system is holding pressure well now. thanks again.
New comment? New question? Please add it here along with photos to help others help you with your compressor and equipment problem!
My Craftsman Compressor fills and holds but once I start using my tools, the pressure drops continuously until it is almost empty. I have my tool setting at 100psi and the tank is 165psi. This is a new problem. What could be causing my pressure to drop rapidly and continuously within a minute or two. Help !!!!!!!!!!
What if you just set up to use tool(s), but don’t actually start?
Or are you saying that the the compressor does not *restart* to maintain the pressure?
The machine will hold the pressure if I set up the tools but do not start. Once I start using the tools, the pressure drops and the compressor will restart. But even though it starts, the pressure just drops continuously. I have to shut off all tools and even then the pressure builds back soooooooooo slowly. I have to stop working for about ten minutes before it (the compressor) builds up and stops and then within a minute I am dropping again once I start using the tools.
Well, if I assume you had this setup working in the past, your compressor is sick.
But if you have not used this setup before, perhaps the compressor is just too small for your tools.
You say you have to stop for ten minutes? Does it take the compressor 10 minutes to stop at full pressure when you first turn it on?
Please answer the above and give us the model/make of your compressor, and ditto for your tool(s), if this doesn’t give you your answer, or you’re unsure.
Maybe some pix, too.