Kobalt pump 040-0431 struggles and shakes

8 years 10 months ago #1042 by melvinlassere@gmail.com
Kobalt pump 040-0431 struggles and shakes was created by melvinlassere@gmail.com
My Model KV5248069 Kobalt compressor will not get to the 175 PSI tank pressure. The pump does spit oil out the crankcase vent while running (not a lot). Everything sounds OK until tank pressure reaches about 80 pounds and then the struggling and shaking gets violent. I turn off the pressure switch at that point. Changed compressor oil. Don't know if the motor will shut down if I don't shut everything off? I guess I want to be sure the pump is bad before dishing out the money. The air compressor is about 4 years old, probably has less then 1000 hour. Label states compressor life of 15,000 hours. I did notice Lowes doesn't sell this unit anymore, Not a good pump????

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8 years 10 months ago #1043 by MTR-Admin
Replied by MTR-Admin on topic Kobalt pump 040-0431 struggles and shakes
I would look at a couple things:

1. Make sure the Belt isn't too tight or loose. When pressing down on the center of the belt (in between the pulley and flywheel) you should have no more than 1/2" deflection.

2. Make sure the motor pulley and pump Flywheel are aligned.

3. You have defective Valves in the pump. If the valves don't open and close as they should you'll get too much back pressure in the crankcase and oil will leak out of the vent, and you'll also get the shaking and rattling you're experiencing.

Feel free to reply once you've checked these few points and we can go from there.

- MTR

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8 years 10 months ago #1048 by melvinlassere@gmail.com
Replied by melvinlassere@gmail.com on topic Kobalt pump 040-0431 struggles and shakes
Thanks MTR.

- I tightened the belt, it had about 3/4" of deflection. Actually had to put a scissor jack between the compressor pump and motor to tighten the belt enough. The pulley alignment was OK.
- I had some air leakage in the tube from the check valve to the pump. Removed the tube and check valve, the check valve checked OK (was not stuck). Assembled everything and got rid of the air leaks.
- Drained compressor oil and cleaned crankcase by removing the fill site glass (pretty gritty stuff). Filled with Kobalt Synthetic Blend oil.

Fired up unit and runs great. The tank pressure gauge lags behind the Regulated pressure gauge. The regulated gauge reached 170 PSI and the unit shut off. The tank gauge was reading around 60 PSI. I'm assuming the tank pressure gauge is defective??? After unit sits (fully pressured up) the tank pressure gauge will climb slowly to around 160 PSI. The crankcase venting is pretty heavy but no oil coming out like before. I did tap with a hammer around the pump valves, couldn't resist doing that.

I will order a new fan belt and 300 PSI gauge. I did notice the compressor had dual belt grooves but the electric motor is a single groove pulley. Is a dual pulley available for the motor and do you think this is necessary or helpful?

Any advise besides what I plan to do would be appreciated. I think your advise on the belt tightening was the major problem and fix. Thanks, Mel

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8 years 10 months ago #1056 by MTR-Admin
Replied by MTR-Admin on topic Kobalt pump 040-0431 struggles and shakes
I would say replacing the Belt (if old one shows sign of wear or is shiny slick on the inside of the V area) and a new pressure gauge would be my recommendation since changing the oil seems to have fixed his shaking problems.

Not sure why the motor does not have a dual pulley, since the pump has as dual-belt flywheel. I would honestly ask a technical rep at the manufacturer by calling them directly at 888-895-4549 (Coleman Powermate made this unit for Kobalt) as they can shed light on this. I would imagine it won't hurt anything if you run one belt, as long as the pulley and flywheel are aligned.

- MTR

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