My 15 year old Kobalt air compressor has been dying over the past few years & some media blasting today really didn’t help. It’s a single stage, 60 gallon upright unit. I’m wondering if anyone has swapped to a different pump all together either single or two stage & what they can advise me on? I’d also like to know if rebuilding the unit would be worth doing. Symptoms: oil leaking, takes longer to fill, starts fast but drops off in a second or so.
Don’t buy a harbor freight pump. My old standup compressor pump went to **** and I bought a comparable pump that was on the unit from harbor freight and although it ran it would not keep up with running a grinder let alone sand blasting. I bit the bullet and bought a new Quincy.
I "helped" a friend of mine with his ailing, ancient compressor. New rings and checkvalve discs and seats, new gaskets. No scoring or appreciable wear in the cylinders. Even had an air compressor repair shop verify the work. Still no joy. It will eventually build pressure but volume is still low. The compressor has sentimental value to him, as it belonged to his dad. Perhaps the compressor is performing as it was designed to but as he is now considering a blast cabinet I KNOW the old compressor will never keep up with the volume needed. My friend spends money freely at times and I keep urging him to bite the bullet and spend some money on a compressor that will meet his needs. I can only speak for myself, but I have better uses of my time than messing with an ailing air compressor. Lynn
I went through this with a friend. He asked me to help him fix his older Craftaman compressor. I looked into getting parts for it and was going to do it when I received some excellent advice from a guy in the shop equipment repair business. He said that if the compressor is that old the tank is probably not in the best of shape either. That can be a safety issue. We decided a new compressor was the best way to go since he had a new blast cabinet and did a lot of painting. Long story short is that when we s****ped the old unit I found that the bottom of the tank was paper thin and very unsafe. ALWAYS BLEED YOR TANK DAILY or get an automatic bleeder.
Is that pump even rebuildable? Kobalt compressors have been manufactured by Campbell & Hausfeld, and also by Coleman/Powermate, and it would be up to you to figure out which yours is, and whether or not you can get parts. Is your air cleaner plugged? That'll make them perform poorly. Sometimes an air compressor can be rejuvenated by cleaning the valve section of the unit. Simply taking the top of the head off where the poppet valves/valve discs are, and making sure they are clean and the springs aren't broken is where you need to start. They are not complicated at all, just keep track of how the springs and discs are installed. Oil leaks can usually be fixed just by dis***embling, CAREFULLY removing gaskets so they can be reused, cleaning, and then putting a thin layer of sealer on both sides of the gasket, re***emble. Don't get any of the sealer on the valve discs. They're just poppet type valves operated by air, and will stick easily. My favorite sealer for this kind of stuff is Permatex Aviation Form-A-Gasket #3. If your compressor needs to be bored due to bad cylinder wear, you might want to consider looking at those available from Surplus Center, or other sources. Here are a couple that are sized similarly to your Kobalt. The RolAir is a Made in Wisconsin unit, and is easy to get parts for later on if you need them. They have been around a while, three generations.
No experiential advice but this should be a great thread. You could take the head off the pump and examine the reeds, check the cylinder wall for scoring, inspect gasket to see if the oil is coming through that, check the ferrules on the tubing... I have a compressor that was leaking from the tubing and I replaced the ferrule and problem solved. It was also making a racket that kind of kept up on me and therefore didn’t realize it. It was also taking longer to pressurize. Removed the head and found that the screws holding one of the reeds had backed out. No damage to the cylinder wall but the screws had been pounded so hard by the piston that they left their impression on the top of the piston and the bottom of the head. New screws and some Loc***e and back in business! Maybe that is “experiential” experience after all!
I’m not at all concerned about the tank. I live in a low humidity climate plus I have a built in cooler & drain both before the tank. I don’t get much more than a few oz each time I drain it, which is the fluid in the metal drain line not even the tank. I’ll probably pull the thing apart & see if I can determine how bad of condition it’s in. I’m ok throwing a couple hundred at it but any more is a waste of money that I can use to buy a 2 stage compressor. I primarily use my compressor for media blasting, but occasionally a few air tools. Quincy has always come up as a top unit but I definitely need a quiet one as it’s in the garage with me. Here’s a video of the compressor running: https://youtube.com/shorts/7YY_3Xy0M84?feature=share
I am a big fan of auto drains. I run them on both our extra-large primary compressor, and on the just large backup compressor. No water collects, because it is shot out the bottom, at timed intervals.
I've got a huge old two cylinder Develbiss that I'll probably have to rebuild or replace pretty soon. Rings and gaskets seem to be available for it but I am in that same dilemma of what's better, rebuild or replace. The dealership I worked at in Waco in the 70's (Frank Weaver Pontiac) had a standing policy that sometime between 4:55 and 5 pm one of the Service writer's jobs was to go out and shut the compressor off and open the drain valve. We never had trouble with our air tools when we worked in that shop and quitting time was quitting time. Back around 2000 I was working as the mechanic on a 1600 cow dairy farm and as much as I fussed the owner would not allow time at the end of shifts to drain the air tanks even once a day and it was a constant battle with water in the airlines and air cylinder failure. It would have been easy enough at least once a day after the milking shift had been finished and all the milk was in the tank. I'd drain as much as 20 gallons of water out of a tank at a time. As far as blast cabinets go or sandblast guns they are just about the same as cutting an air hose in two and letting it blow as far as the compressor is concerned. Real hard to keep up with the air flow.
How is that compressor piped between the pump and the tank? In the video, it looks like there could be a regulator in the line. The only devices that should be in the line would be a water separator at the outlet of the aftercooler and a check valve. Any device that creates a pressure drop affects the flow rate from the pump to the tank, and could create the impression that the pump is worn out when that's not the case.
It’s hard to see but the regulator is right before the air hose after it comes out of the tank. I set up the after cooler (****** cooler) behind the pump flywheel which pushes air through the cooler. Air from the pump goes directly to the cooler. From the cooler it goes to a fluid separator with an automatic drain (thus the bucket) & then into the tank. From the tank it goes into another fluid separator then the regulator, then the hose. It’s worked quite well but took a fair amount of time to create it.
What transmission cooler do you have that is rated for tank pressure, plus a safety factor, on an air compressor. Both of my compressors have after coolers, and each is made of cast Iron. The fluid separator between the pump and the tank is causing a flow restriction.
Sounds like it’s time to toss it all! Compressor only goes to 150PSI max. B& M trans cooler information; 11" x 8" x 1-1/2" racing model is rated at 20,500 BTU, and pressure tested to 200 PSI
Opened the top but gotta run for a while; How does one go about opening the rest of it, anything specific to know?
For things like this, the general rule is a 2:1 safety factor (often 3:1 for life-safety equipment. Think elevators with 3 cables.) If B&M abided by that, then this cooler has a maximum safe operation pressure of 400psi, but they will never tell you that. You too should be after a 2:1 safety factor. In the case of your compressor, that would be 300psi, or 75% of the theoretical safe maximum for that cooler, ***uming that it has a 2:1 SF. That is a 1.33:1 safety factor. You would not catch me doing that. Now, if they only really did test it to 200psi, then you still only have a 1.33:1 SF at 150psi. If your shutoff switch sticks, and you make 51psi before you get to the switch. What happens then is anyone's guess. While it might be ok, pressure wise, it is a fluid cooler. Not to get into esoteric arguments about how air can behave like a fluid, but fluid coolers do not often make good air coolers. Did I mention that mine are made of cast Iron? If it presents any restriction to air flow over just a line from the pump to the tank, it's not doing you any favors.
Agreed, I should have gone bigger air lines instead of staying with the same size lines it came with. I stopped in a local place to look at the Quincey air compressors they sell & I was surprised to see this large of a hose to the tank. Tearing into the pump further shows no real signs other than oil which is probably rings need replaced. Need to pull the cylinder piece off next & see what it shows.
Hello, As much as an air compressor works, recycles and is usually inside of a garage or workplace, it might be time for a new one. We had a giant tall Kobalt unit inside of our house recently. It was a new model and was relatively quiet versus my old one that I had in the garage. The tall compressor unit owner had replaced a 10 year old unit because it was, well dinged, up, pushed around and well used in his construction business. He is into safety and a new one paid for itself in his business. Normally, if it is stationary in the corner of a shop, it might not be bad to replace the motor unit. But, if it is 15 years old, well it may be time for a new one to sit in the corner doing its thing. I was amazed at how big the unit was and how much quieter it was than my old one. I did not have to shut the door when he fired it up to finish the work. Jnaki The contractor said it is one of those things he used everyday. While the old one was still working, he could just feel it getting old and the cost of a new one was in the books. Plus, he was in client's houses with the compressor and he did not want a major incident with any old compressor. Better safe than sorry... Plus, our house contract job, probably paid for it...HA!
I wiped out the cylinder walls & piston tops, they look pretty good. I also moved the crank around & really didn’t feel anything loose in the crank to piston, not piston movement. ***uming I could feel play in things. Looking things over I did find a few issues elsewhere: 1) the belt was loose enough that I could slide it on the two pulley’s. 2) 1/2 the bolts holding the motor on were loose. 3) the bolts holding the head on were also a little bit on the loose side when previously removed. Thus I went over everything, tightening things down hood & tight. I’ll also throw some Loc***e on the bolts when mounting the head. So I decided I’m going to put it back together & see how it runs.
I too thought that when I first saw the dark lines but it doesn’t appear to be & I can’t catch a finger nail on it either. if I’m going to up the size of the lines I probably should drill out the hole on the head while it’s off & re-tap it but I’m not sure I want to do that extra right now.
I'm thinking this could be the reason the pump slows down almost immediately after starting. There is very little plumbing in between the compressor head and the tank, which means very little volume. The compressor fills that small volume to a high pressure quickly, and then has to continue to pump at that pressure to force air through the separator. I'd try removing the separator as a test, plumbing the outlet of the cooler directly to the tank and see if that doesn't have an effect. A compressor running at near maximum pressure all the time is using a lot more electricity, and wearing out much faster. As far as tearing it down further, you have the "head" off and can see the pistons, correct? How do the walls of the cylinders look? The reeds hitting the steel stops aren't going to make much noise. Loose pistons or worn rods are more likely to make noise. Sometimes the noise is just loose bolts that hold the compressor to the tank.
Good idea & that’s what I was thinking of doing, putting the line directly to the tank & see what it does. I can always add one thing at a time back in between & see what it does. I put the pump back together tonight with a little Loc***e on the head bolt threads as well. A buddy was telling me tonight that he had a check valve that was hammering & the sound was fixed when replaced. Should be interesting, I’ll give it a start up tomorrow morning & see what happens!
Finished ***embly & fired up the compressor a few minutes ago. I had to run the lines like I had it, although I will change those lines up to at least 1/2”. At that time I’ll byp*** the water separator & see if it makes any difference. Overall it’s running well, back to good working condition, just still loud. https://youtube.com/shorts/BLAw6VEpxdo?feature=share
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