Craftsman Air Compressor wont pump over 40psi

[red73mustang]

Hi folks, I purchased a used Craftsman 3HP 15 gallon potable compressor model 919.167240 that is supposed to be rated for 150 PSI, but it wont get over 40 PSI no matter how long I run it.

I should point out that I connected a "cheapo" Harbor Freight regulator to it that is supposed to be rated up to 200 psi

Any ideas?

Thanks, Chet

 

[G_P]

Remove the regulator and check pressure directly at the tank.

Does it leak down or will it hold pressure?

sent from the toilet via tapatalk 2.

 

[red73mustang]

Tank seams to hold pressure and no sign of leaks. will try another regulator

 

[LEVE]

I'd be removing and examining the piston/rings and gaskets on the compressor.

 

[red73mustang]

I changed the regulator, same result, wont go over 40 PSI. It's an oil-less type pump so I wouldnt know where to beging to look for gaskets or pistons.

 

[Gary S]

Oil less pump says it isn't worth fixing. That is why almost everybody here recommends you get one with a real piston pump with oil in the crankcase. They don't last long.
Your life will be easier if you dump it and go out and buy something better rather than throw more money into a bad design.

 

[G_P]

If you junk this one save the tank. You could make a sweet portable air tank out of it!

Sent from the toilet using charmin ultra

 

[c7fx]

I just fixed one of these and the gasket at the pump shredded. Easy fix and cost less than 10 bucks

 

[RVDan]

likely a bad intake valve

 

[SGKent]

I've seen replacement regulators that had different configurations on the ports even though they look identical so it may be dumping air as fast as it pumps if the regulator is weird like that. I know that because been there done that.

 

[red73mustang]

Thanks C7fx, can you elaborate on how you fixed the gasket at the pump? Im considering getting a piston/rings and gaskets kits and maybe the sleeve.

Thanks, Chet

 

[c7fx]

The one I fixed I took the top of the cylinder off and it had a gasket and two small metal valves. The gasket separated the valves and was blown out. So the compressor would work but would not carry too much pressure.
Pull the top of the cylinder and see whats going on.

 

[shoot summ]

My 20+ year old Sanborn had a similar issue, would run constantly and never get above 30-40lbs. I was going to junk it and couldn't bring myself to do it. I pulled the head off and everything looked good. In the process of removing the head I also had to disconnect the feed line to the tank. The aluminum line had cracked right where it attached to the head. Cut the line, new ferrule and it works as good as it ever did.

 

[PWC Repair]

Sounds like a bent or warped reed valve. Go ahead and take it apart, you can't mess it up as it's already broken. It should seal off and lay dead flat, I'm betting it's warped from overheating.

 

[marinusdees]

Oilless use Teflon rings and brass cylinder liners. The Teflon sacrifices itself to the brass. It runs hot and when it is worn out, it is worn out. It does not take long. They are throwaway units. I won't even buy a new one.

 

[cityhick]

I have one of those "junk oil less compressors that you should just throw away". That seems kinda stupid to me but whatever. Anyway I got on Craftsmans website and ordered a complete rebuild kit that came with everything I needed including a new sleeve. Works good as new again for around $50.00. Just think, if I would have thrown it away that would have been dumber than someone even suggesting to throw it away

 

[PWC Repair]

I was thinking this valve may be damaged. My buddy had one doing exactly that and this was his issue. http://www.searspartsdirect.com/partsdirect/part-number/Z-AC-0032/0009/919

 

[cj7365]

Oil less pump says it isn't worth fixing. That is why almost everybody here recommends you get one with a real piston pump with oil in the crankcase. They don't last long.
Your life will be easier if you dump it and go out and buy something better rather than throw more money into a bad design.

Wrong, I just wrote a thread on this, I bought the rebuild kit for $42 bucks and my compressor is good as new.

take the compressor head off and inspect the piston sleeve and ring if they are chew up

this is the kit I bought

http://www.ebay.com/itm/Air-Compres...438?pt=LH_DefaultDomain_0&hash=item3cbd685a46

For $40 you cant go wrong unless Gary is going to help you buy a new one

Here is my thread about my crapsman 30 gall compressor, It has pics of the chewed up cyclinder and ring

 

[38Chevy454]

It could be the ring is worn, but if this started happening relatively recent, my bet is the reed valve is not sealing. Like they said, pull the head apart and it should be pretty obvious if the valves are the problem. I have an old Devilbliss oil-less I keep around as it is handy for traveling to get dead car projects and 120V. It had a reed valve actually split and i put a new one and good as new. Never have put any ring or piston in it. As a back-up it serves the purpose fine. I put the valve plate similar to what PWC linked.

If you do decide it is too much to repair, keep the tank, but get an oil-lubed compressor. WAY quieter and should outlast 5 oil-less models.

 

[kams1973]

Chances are it's the pistion and cylinder. Occasionally you'll get lucky with a blown gasket or debris under a valve.

 

[red73mustang]

So I finally took my Craftsman Oil-less compressor apart and was happy to find that only the reed valve plate had one of the "reeds" with a chunk missing from it. Parts are only $10 shipped on the auction site.

Piston and sleeve look good, no scratches and tight fit. While I'm in there should I clean anything, modify or oil anything? Looking forward to getting this unit up and running!

Thanks, Chet

 

[nadogail]

Glad it worked out for you.

I have a Devilbis oil less upright, and the tube to the pressure switch developed a hole in it. I used 12 inches of quarter inch copper tube and two compression ferrules.

 

[Fixnair]

Don't oil anything on the inside. It has been designed to run W/O oil ant the introduction of oil can have a negative result.

 

[rayra]

OP's post doesn't make it clear if the motor / pump cuts off at 40psi, or if it just pumps continuously and never reaches above 40psi indicated.

High-pressure cutoff could be the trouble if the former. Bad rings or seal somewhere, otherwise. Are there any leaking sounds? Was it bought used, previous user might have slagged the piston / bore.

eta nevermind, caught the rest.

if the bore is clean, not much to do.

 

[red73mustang]

Update: So I replaced the read valve plate assembly, the tube seal at the head, the air line and now it won't pump over 15PSI!!! There are not audible leaks present and the piston has no slop in it. I should note that the new read valve plate differed from the original in that it was not "recessed" for the piston and did not utilize an O-ring like the original. I just assumed that the replacement unit superseded the old design. Really starting to hate this thing, but now its become a matter of principal.

Just noticed that this thread is in General Garage, Can it be moved to General Tools??

Thanks

 

[red73mustang]

So I know the tank is getting minimal air pumped to it (approx 15PSI) because it blows off when I pull the relief valve, but it won't go any higher. This must be some type of assembly error on my part after replacing the reed valve plate, seal at the cylinder head and the air tube going from the head to the tank. I should note that I have 2 regulators installed in series (don't remember why). Hoping for an obvious error that someone could help with?

Thanks, Chet

 

[finn]

Another vote for a cracked reed valve.

Take the head off and inspect the valve, and look for obvious leaks as others have described before ordering any parts.

You have nothing to loose.

 

[gungatim]

pics would help. though I hate those oil less compressors, they are super simple to fix. sears parts direct has the entire drop in cylinder, rod/piston/ring assy fairly cheap. the cylinder is not brass, never saw one that was, just steel or with a coating on it.

 

[LS6 Tommy]

It's an oiless pump. IMO, it's not worth rebuilding, but here's the parts list:

http://www.mastertoolrepair.com/air-compressor-pump-parts-a04714-p-22886.html

Take note that the rebuild kit is only for screw top pistons.

Tommy

 

[Speedfreak11]

I had a similar problem with a small bostitch oilless. Replaced nearly everything, and every time I put it back together it wouldn't build pressure, and would stop and some random psi. I finally figured out it was the unloader valve. $6 later, perfect working compressor. See if the unloader is closing.

 

[red73mustang]

Thanks Speedfreak, just to be sure on terminology, the Unloader valve is it inside the pressure switch, is it another name for blow off calve or something else?

Chet