Air compressor taking longer to recharge.

[atikovi]

I have a 15 year old Craftsman 60 gallon 2 stage 175 psi compressor that's taking longer to recharge than it did a year or two ago. It kicks in at maybe 150 psi and may take 4 or 5 minutes to get to 180 psi and stop. Before, it probably only took a minute or two. The motor itself seems to run fine. Are there any valves that may wear out and cause this? Thing has run flawlessly except for something external was replaced under warranty the first year.

 

[jonesg]

repaired mine with a reed valve kit, came with new gaskets for less than $20.

Order a kit and fix it.

Craftsman air compressor parts | Sears PartsDirect

Craftsman air compressor parts - manufacturer-approved parts for a proper fit every time! We also have installation guides, diagrams and manuals to help you along the way!

www.searspartsdirect.com

 

[Schurkey]

Agreed.

My "Industrial Air" compressor took longer to charge, and wanted to vent out of one of the safety valves. The inlet valve sealing ring for the second stage was damaged, so second-stage air pressure was filling the intercooler, blocked only by the first stage exhaust valve. The valve was OK, but the sealing ring was broken.

Took me awhile to figure out how the valves came apart, and I had to borrow a "special tool" from the compressor-repair people to unscrew the valve assemblies.

 

[atikovi]

This is my model number, https://www.searspartsdirect.com/model/6683df407o-000247/craftsman-919165612-air-compressor-parts
I assume you mean #14 and it takes two. Over $100. Maybe if it gets worse.

 

[jonesg]

I wouldn't assume, I took mine apart first and found the problem .
Its usually fairly obvious, I'm no mechanic, just a retired baker here.
Before wrenching on it, spray some soapy water around the heads, unions etc, could just be a rubber seal/gasket.
then I took the part number and ran it through google to find alternate or even OEM supplier.

With the example you posted, I see those parts anywhere from $18 to $30ea just by googling.
Cheapest will be from ebay for Part #Z-AC-0032
Sears wouldn't be where I'd buy the part. They're for lookup only.

Google Search

But until you find the exact problem first its impossible to have an intelligent conversation.

 

[Bayday]

Is it an oil-free model? It looks like one I recently repaired. The piston seals are a (notoriously frequent) wear item, and sometimes the (fortunately replaceable) cylinders too.

 

[atikovi]

Yes an oil-free model.

 

[Citation]

#14 is a head/valve plate. That is likely good. The part you would need is the one that isn't available at your link, the cylinder and ring kit.
You might pull the head and see what condition the cylinder is in. If the cylinder is in good shape you might just need some new rings
https://www.walmart.com/ip/Uxcell-6...r-Replacement-Piston-Ring-Dark-Grey/891037065
Note - I have no idea if this fits your compressor, just an example

Else you would need a kit more like this

Devilbiss Compression Sleeve/Ring Kit K-0650 | Zoro

Order Devilbiss Compression Sleeve/Ring Kit, K-0650 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.

www.zoro.com

I suspect most of these parts are all the same sizes even if they don't say as much. However, guessing and checking would certainly be a crapshoot.

 

[redmondjp]

Honestly, these consumer-grade oilless compressors are rarely cost-effective to repair. You could spend $100 to replace the valves and gaskets, and then find out that your teflon piston rings are shot, and have to take it apart again and spend even more money (assuming that parts are even still available).

I'd put that same money towards a new compressor. 15 years is a pretty good lifespan for an oilless unit.

 

[The Cobbler]

2 stage oiless? or 2 cylinder oiless?

probably the teflon ring(s) are bad and possibly the cylinder(s) scored . both can be had for reasonable $$$$ sometimes, sometimes not. replacement rings can be found on ebay for several common sizes, if yours is field replaceable on the piston. sometimes they are crimped on and not easily replaced.
I would also look at all connections, piping , gaskets etc for leaks while under compression. could be an easy repair bad seal , cracked pipe etc .

 

[atikovi]

2 stage 2 cylinder oiless.

 

[Bayday]

The piston seals are a (notoriously frequent) wear item, and sometimes the (fortunately replaceable) cylinders too.

I wish to clarify the above. It seems to be a generally held belief that oiled air compressor pumps (particularly the heavy, non-homeowner-oriented models), that are both a) run at the correct speed, within duty-cycle & pressure specifications, and b) maintained on a reasonable basis with air filter & oil changes (of the proper type), will likely operate trouble-free for a very very long time. In comparison, oil-free air compressor pumps have issues sooner; their operating costs are higher. Issues with receivers (tanks) are another matter (drain them frequently!).

The value of oil-free compressed air has to be judged by the end user. A slightly involved analysis can be done to determine whether requirements of the compressed air are best achieved with an oil-free pump or an oiled pump followed by some number of filtering mechanisms. A direct replacement of the OP's oil-free, 2-stage, 60-gal, upright, wheeled air-compressor looks to be $1000+ new at this time. Depending on situation specifics of course, it may be cost-effective to repair. If the oil-free air requirement is unnecessary, the decision to repair is more difficult.

I concur with the advice that diagnosis is the proper course of action; a number of leaking things could be the issue. However, my bet is on the 15 year old piston rings (and cylinders if you're mildly unlucky). If you take the shroud off, you can look into the bottom of the cylinders and see much of their walls (manually turn the motor if necessary) and I think you may be able to see some of the piston rings (and possibly a glaring issue if lucky). From that Sears link, one each of kits K-0648 & K-0650 will allow you to change both cylinders and rings. I'm familiar with the K-0650 kit, but the K-0648 kit I see on ebay has far more items.

Is the compressor louder than it was years ago? I feel like mine became quieter after replacing the cylinders & rings (a chunk of ring was missing on mine).

I believe you likely have a rebranded DeVilbiss air compressor. Do you see "AC-0782" somewhere on your unit? See here for more info: https://www.garagejournal.com/forum...or-craftsman-devilbiss-air-compressor.482736/

 

[Schurkey]

I know some folks with oil-less compressors. They're louder than kicking a half-full box of marbles down the stairs.

Just getting rid of the excess noise would be worth upgrading to a oiled compressor.

 

[Citation]

I know some folks with oil-less compressors. They're louder than kicking a half-full box of marbles down the stairs.

Just getting rid of the excess noise would be worth upgrading to a oiled compressor.

This always depends on the specific compressor. The oil free compressors from 20 years ago were typically quite loud. The "quite" compressors from California Air Tools and the like are typically significantly quieter than a low RPM belt drive oil lubed compressor.

 

[atikovi]

Ordered two of these ring and cylinder kits https://www.amazon.com/gp/product/B008X0J9KG/?tag=atomicindus08-20 Says made by DEVILIBISS which I hope is just a typo and is actually Devilbiss, not some Chinese knockoff.

This is down in my basement and there was no way I could have brought a 500 pound oiled compressor down the stairs. If this is all it needs in 15 years, oil-less seems the way to go. The only maintenance I do is drain the tank every year or so, and it's been trouble-free.

 

[Schurkey]

2 stage 2 cylinder oiless.

Ordered two of these ring and cylinder kits https://www.amazon.com/gp/product/B008X0J9KG/?tag=atomicindus08-20

Seems unlikely that a two-stage compressor would have two identical pistons.

[Edit] Never mind. They change the crank stroke instead of the bore size-- About 1.5" stroke on the low-pressure side, about .5 stroke on the high-pressure side.

 

[atikovi]

Seems unlikely that a two-stage compressor would have two identical pistons.

I didn't buy pistons.

 

[The Cobbler]

Seems unlikely that a two-stage compressor would have two identical pistons.

[Edit] Never mind. They change the crank stroke instead of the bore size-- About 1.5" stroke on the low-pressure side, about .5 stroke on the high-pressure side.

I didn't buy pistons.

he was refering to the fact that both rings are the same OD, usually 2 stage compressors have a smaller diameter second stage piston.

 

[PoorUB]

One man and a healthy teenager could get a 500 pound compressor down your stairs. It just takes some thought and planning.

Two of us loaded a 500 pound compressor in the back of my pickup with no lifting tools. You just need to be creative.

 

[atikovi]

Maybe so, but the oil-less type seems to need much less maintenance with fewer parts to wear out, and when they do wear out, they are simple to replace.

 

[VolvoRyan]

Let us know how you make out. I'm always curious to hear how these repairs work out. There's definitely risk of chasing your tail. There are valves, piston/cylinders, seals, and check-valves. A lot of these wear in concert in these units. Leak detection can get tricky since everything runs hot enough to boil off soapy water very quickly.

-Ryan

 

[atikovi]

I don't have any problem with leaks. Tank pumps up to 180psi and motor cuts off and it will still be around that pressure the next day if I don't use it. It just that it takes a long time to get there.