2 stage puma air compressor

[1957hd5]

Hope it is ok to ask air compressor questions here.
A friend of mine has a garage and recently his air compressor starting blowing oil out the breather and really slowed down. He doesn't have time to fix it so he bought a new one and I bought the old one for $500.00.
Usually would not have gave that much, but he just put a $700.00 7.5hp Leeson motor on it. New the compressor is $1900.00.
I assumed it was just the valves. They were carboned up really bad. Then I noticed the high pressure piston would drop about a 1/4" on the downstroke. I took all three cylinders off and the low pressure cylinders and piston look ok. But the wrist pin on the high pressure had eaten through the bushing and put an groove in the rod.

The crank looks a little rough on the bad rod area, the bushing (bearings) were not ate in two. Should I polish the crankshaft in that area? The crankshaft looks fine in the other areas. BTW it will not see even a fraction of the use that it has been used for.

A new rod, piston, new high pressure valve and all new gaskets and air filters is going to cost about $250.00.

[KE4AVB]

Don't much at all about air compressors but I would if the crank journal is a little rough (which subject to opinion) would consider replacing the compressor. It all depends if you planning to push it back to factory max compression or not. From what I gather the Pumas are setup to go to 175 psi max but this may not the spec on the one you have. Its the tank design safe pressure limit and condition you got to worry about.

If I was not going to be using it under medium to large shop conditions I might consider just dropping in a 145 psi dual stage compressor from HF and set it at that limit if the tank can handle that pressure. That is if there is enough room and mounting is isn't a problem.

I have been doing a looking around for a potential upgrade to my air system and have found that carefully shopping you can find a 60 to 80 gal system fairly reasonable priced; actually just a little more than what you paid for the Puma but I don't know the tank size of the one you brought. I even found a 60 gal 3 hp system that could deliver more CFM than my current 25 gal 5 hp system. I just haven't made my mind up yet.

Now this just my opinion as I am on a very tight budget here but still got to have reliable equipment so I don't just buy what ever just because it cheap either. It takes careful consideration but I make a purchase.

[Arkie]

IMHO:
If the crankshaft throw looks rough you need to get a opinion from a crankshaft machinist. (probably needs replacement crank or machinist attention)
If that is the 7.5 hp 3 cylinder 2 stage it was originally built for industrial use, and if you don't really need a compressor that large in HP you would probably come out better parting it out. A 7.5 hp motor will usually bring close to $250 with the starter contactor control box and motor.
Sounds like the unit was rode hard in the other shop, has new motor and now bad valves and piston. Most likely they did not do proper preventative maint. Need to change the NON detergent oil in those quite often.

I had a 5 hp 2 stage (2 cylinder) with a 80 gal tank with a bad compressor (bad crankshaft) and after careful shopping I looked at Northern tool and HF 5hp single stage 2 cylinder compressor and bought the HF compressor for like $135 and a 2 yr warranty. (I did not need the industrial 2 stage for my shop and it would cost as much or more to overhaul the bad compressor as it would to buy a new equal industrial compressor pump, and I like to overhaul stuff and like to work on compressor pumps. The 5 hp HF pump has been in use for 4 years with no problems. (It had good reviews but could blow any minute.???(and not be a surprise)
If you need a industrial use compressor pump get industrial eq, don't expect HF or NT to operate as industrial eq on a constant daily basis, it's part time residential useage.

[1957hd5]

If I hadn't already ordered the parts, you all would have convinced me to replace the pump with the hf. I looked at it a long time...
They only have single stage pumps now.
If the parts I ordered fix it, I will be tickled to death. Right now I have the valves in my ultrasonic cleaner with some utterly fabulous cleaner and it seems to be working.
Other than needing some cleaning it looks brand new. Still bright shiny blue. He hasn't had it all that long just ran 10w30 detergent oil in it . According to the guy at Puma that is what caused the build-up and failure of the high pressure piston and rod.

[1957hd5]

Btw plan to drop the pressure to about 150 lbs. Right now I have a sanborn 60 gallon single cylinder. That can't keep up with anything. My son in law wants it, told him $100.00. Think that's fair? He needs to air up tires, blow out filters etc .

[KE4AVB]

I figure there was a reason you want that size pump which I mention CFM volume was a determining factor on replacing the pump. Small shops like mind don't need the same CFM that larger shops needs but there times it would nice to have a little more reserve here too.

I have started replacing some my tools more powerful versions that actually use less CFM. Take the AirCat 1150 I just purchased runs rings around my Campbell Hausfield. It has more power, less noisy, and uses less air. My compressor would come on every time I used the CH impact but even after hammering on a nut that was already tighten to 151 ft-lbs the compressor never came on and that with a 25 gal tank. It finally came on the third nut. That CH couldn't even remove my truck's lug nuts without kicking in the compressor.

It hard to say what the value would be but when its family it does help to sell at a lower price and even sometimes just give them a used piece equipment especially they are struggling to make it. As someone once said to me "Charity starts at home".

Good luck on your rebuild and let us know it turns out.