KOBALT Quiet Tech 26 Gallon Air Compressor FAILS AGAIN! Watch this long term review before buying!
The KOBALT Quiet Tech 26 Gallon Air Compressor has failed for the second time. The first air compressor lasted about a year before it became very loud (sounded like it was leaking air from compressor cylinder area), and would take longer to refill. I returned it (under the 3 year warranty) and replaced it with another, hoping that it was a fluke. Since then, I've learned more about oil free compressors and how they can be serviced. Companies like California Air Tools off rebuild kits for their compressors, which includes the piston cup, cylinder and reed valves. Generic piston cups and cylinders can also be purchased, but the size has to match the original.
So when the second KOBALT Quiet Tech 26 Gallon Air Compressor started exhibiting the same symptoms after only 6 months, I first called KOBALT service to ask if they had rebuild kits. The only replacement parts that they offered were components external to the compressor motor, like air line fittings and parts. KOBALT's only solution was to return the compressor and get a new one, which is a huge pita and wasteful. I can take apart the cylinders and replace the parts far faster than the time it takes to return and buy a new one of these compressors.
Therefore I've purchased some replacement piston cups that fit and worked great (so far). I'm still searching for replacement cylinders, although mine are still in good shape.
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DIMENSIONS
The cylinder ID measures 69.8mm. Cylinder height = 40.5mm
The piston ring ID is 54.36mm. Thickness = 1mm
PISTON CUPS
The original piston cups have an ID of 54.4mm and thickness of about 0.85mm (they must have started out at 1mm thickness and then compressed/worn to the 0.85mm I measured.)
The replacement piston cups I found are sold for a 1500W compressor, and the dimensions are 72mm (2.83 Inch) OD, 56mm (2.2 Inch) ID, 1mm (0.04 inch) thickness. The ID is not a tight fit onto the piston head, but if installed carefully and centered, works perfect.
A heat gun must be used to remove the screw from the piston head part that clamps the piston cup. The screw is held in with a very strong threadlocker that has to be broken down by heating it up with the heat gun. We used 600F setting. A cordless impact driver is also very effective for removing the screw easier once heated.
Threadlocker must be used when reassembling to prevent the screw from loosening. We tried using Red (high strength) Loctite 271, but it failed to keep the screws tight, causing the piston head part to loosen and causing a lot of noise. Loctite 271 has a max temp rating of 350F, so the heat inside the compressor head may be causing it to break down. 271 failed twice, so we switched to Loctite 272 (high temp, up to 450F) and it has continued working without fail.
The new piston cups can be installed without removing the piston and piston rod. Before installing the cylinder, bend the edges of the piston cup upwards and as close to the piston as possible. Slide the cylinder on at an angle (Watch the video), and rotate into position to prevent damage to the piston cup.
CYLINDER
The original cylinder ID measures 69.8mm. Cylinder height = 40.5mm. The cylinder doesn't appear worn, so it should be OK to continue using it. I can only find taller cylinders with that diameter. Worst case I will need to buy the taller one, and use the lathe to shorten it.
