So a while back I picked up an air compressor from a sketchy body shop for $75. It always pumped slower than it seemed it should, so I figured that it had just been run hard and needed a hone and re-ring since I seemed to be getting a lot of blow-by.
Today I opened it up to rebuild it, and, well:
This part appears worn beyond specification:
To be continued...
Personally, I would not rebuild a $75 air compressor with a thrown rod. I would consider it the price of a lesson not to buy shit out of sketchy body shops. $75 goes a long way towards a disposable harbor freight air compressor. My grandfather bought a 6-cyl schramm for $1000. Theoretically, it would have sandblasted a 5/8" nozzle. Practically, we never got it running either.
Here's a picture of the compressor in question: Don't believe the 7 HP marketing bullshit; it's a 4 HP motor. The pump itself is an oiled iron-body USA-made model that's supposed to last a good long while. Nothing else in the pump has any axial play. The reason it was so cheap is it was sold to me in almost-running condition; the guy had robbed the pressure switch and some plumbing to fix up a beast of an old Qunicy 2-stage compressor. (I in turn robbed a pressure switch and some plumbing off another air compressor that well and truly shit the bed.) I've been trying to figure out how the conrod failed; there's a burr on the crank journal, but I'm not sure if that's what caused the failure or if it's a side effect. The rod looks like it got twisted and then it grabbed the crank and shattered. (Behind the compressor in the picture are two 25 gallon tanks that put me at 110 gallons of air storage, which is quite nice when running a die grinder or the like.)
Die grinder is about throughput. I guess you can make that up by storing a hundred gallons of air. Certainly cheaper. It probably failed because the guy raiding it for parts let the oil out. At least, I would consider that a keen possibility and recognize that the rod isn't the only part to fail as a result, just likely the first. A 7hp replacement pump looks to be about $750. That kind of money gets you big boy toys. I would save the motor, take a zipsaw to it and put it in the recycle bin.
There are only about 4 other moving parts in the whole compressor, and they're all in good shape--no axial play at all. A new con rod and one crank bearing (that I need to remove to install the conrod, plus it has a wee bit of wobble to it) is under $50. I think I can deal with that. I can replace this pump new for about $300...$750 would get me into a very nice 2 stage pump. I'd love to do that but I have other things to spend that money on...
I'm buying 100 psi air compressor from harbor freight this week, on sale with the coupon for $39.99. I need it to blow the gunk out of cooler radiators at the shop. Blowing those radiatorsout can double the time between service calls. Getting ready for summer.
Buy one of these instead. I bought it to use instead of canned air on photos but ended up using it a lot more often as a leaf blower. Thing is intense and is designed for sensitive work. Comes with a buncha nozzles. Made in the USA (which Harbor Freight definitely is not). Use it more often and keep those coils immaculate.