Air compressor problem

[311Hemi]

I have an old craftsman air compressor thats probably at least 15yo. Well, I got it from my old man a year or so ago and the oil at that time was in need a changing because it was getting tight after running a few min (I know it was too late already). The oil had not been changed in YEARS. Anyways I put fresh oil in it this year and after running for a few minutes everything gets real tight, enough so that the motor cannot turn it. I did not really use it since I got it from him, but he said it was getting tight when he gave it to me. Doh!

Is there anything I can do to save this machine?

[Macgyver55]

Is it building air pressure when it does run? Does it sound/act like it is "getting tight" from lack of lubrication, or could it be building to much pressure to keep turning? If it is a lack of lubrication, chances are it will cost more to fix than replace. The crank shaft, rod and piston are similar to that of a small engine so they would need replacing if they are scored.

If it is a case of over-pressure it could be the pressure relief valve or the pressure cutoff switch or a combination of both. I guess its kind of hard to tell without seeing it.

[Christopher Quast]

Hey Hemi I had the same problem with mine and I was told to run ATF in there and now it will start up no mattter how cold it gets and I've heard of guys running kerosene in them or diesel fuel with no problems try tranny fluid and let us know if it worked for you.

[311Hemi]

 Originally Posted By: Macgyver55

Is it building air pressure when it does run? Does it sound/act like it is "getting tight" from lack of lubrication, or could it be building to much pressure to keep turning? If it is a lack of lubrication, chances are it will cost more to fix than replace. The crank shaft, rod and piston are similar to that of a small engine so they would need replacing if they are scored.

If it is a case of over-pressure it could be the pressure relief valve or the pressure cutoff switch or a combination of both. I guess its kind of hard to tell without seeing it.

It is building air pressure, I guess it's possible it could be building to much. I did not think of that, but also not sure what pressure it would start to do that as there is a pressure gauge on it. If that was the case then I should be able to release the pressure and it should run normal again...correct? Otherwise most likely an internal issue?

I did just put new compressor oil in there, so I am not sure if the ATF would make much of a difference at this point. It was not cold out when I was running it. It turns on an runs fine at first, but then I turned it off and then turned it on and it was much harder to turn the compressor part by hand.

[Macgyver55]

The pressure would have to be pretty high AND the tank relief valve would have to be stuck closed in order to slow or stop it while running. The tank relief should pop well before the pressure ever got that high.

Now, if the problem is that it just wont restart after shutting off, it could be the relief valve is not opening to relieve the head pressure. If there is pressure left in the cylinder when the motor stops, without being released it wont be able to restart it, and it would be hard to turn by hand. I had this problem with a small compressor I have at my cabin. (Coincidently its a Craftsman) Replacing the valve solved that for me. This would definitely be your best case scenario.

I guess I would run it until it shuts off. (if it will) There should be a hissing sound if the relief valve is working. If not, drain all of the air quickly, then see if it will restart again. If it does the relief valve is suspect. On mine the valve is located right where the tube from the compressor head enters the the tank.

[captainstevo]

I have a Craftsman that was starting to act similiar, it ended up seasing up after I had tried a couple of simple fixes ( ATF, and a couple others) I ended up replacing it and using the tank as a pressure carry tank. I would have cost more to fix everything than buy a new one. I am a contractor so I use mine every day, which may have had a part in why mine didn't last as long. Basically I am saying it might be wise to start keeping your eyes open for anouther compressor. If you shop around you can find them on sales and offers with free nail guns or air tool.

[311Hemi]

I will check the things out mentioned above, but I do get a hissing out of it already....just not sure where it's coming from (if it is the relief valve or not).

I will probably just start watching for some sales for a new compressor at some point. I don't use it a ton right now, but I could be looking to sometime soon.

Thanks for the input guys!

[Surface Tension]

I just retired and old Craftsman that did the same thing.