Craftsman 33 gal Air Compressor 6 hp Horizontal k Oil Free Pump - Answered Questions & Fixed issues

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Hi, I need a manual for Sandborn B165B500-25 air compressor too. Did you have any luck finding one?

Sounds like part #27 is worn. Replace # 24 24 A 24 B and 24. the cylinder may be worn. Perhaps depending on the age and time and labor replace with new comp. maybe Dewalt.

Check the circuit feeding power to the compressor. These conductors may be too small. Conductors have a degree of resistance. Resistance consumes power. The power conductors consume is dissipated as heat and present a voltage drop to the equipment being served. Length and size of the conductors determine power loss. An electric motor momentarily needs up to six times the running power and this power loss is squared ( PxP) at start up. The bottom line: Shorten the length of the conductors or increase the conductor size to avoid voltage drop.

Some of the craftsmen compressors have pistons that are coated on the top of the dome. Once the coating wears off, they have severe loud piston slap. If you continue to run it the way it is, it will snap the connecting rod in half or break the piston and possibly the cylinder.

most likly the regulator is no good, some can be serviced, some are sealed units.

Some pressure switches have a valve that reliefs the compressor head pressure when the motor stops and closes the head pressure relief valve when the motor runs.
There is a check valve that keeps air pressure from coming back to the compressor head and the relief valve.
I think the check valve is leaking tank pressure to the relief valve and compressor head.
The check valve is where the pressure switch mounts on to and it mounts threaded on to the compressor tank.
Try replacing the check valve

Take a spray bottle and put some soapy water in it; spray it on the path that air flows (line from pump to tank, pressure regulator, air line fitting) to find where the leak is. Once you find the leak will determine what has to be done to fix it. **the soapy water spray will bubble wherever air is leaking**

Some motors will work with 120 volt or 240 volt You have to remove the small cover on the end of the motor & see if there is a diagram, where you move the wires for different voltages

You have to drop the oil pan . Since it's 4wd you won't need to jack it up. The pump has 2 bolts. The shaft has a slot in it that engages the distributor so when going back with the new one be sure you line up the shaft before tightening the bolts.

remove shroud and see if fan is broken but may be piston is shot

Just fixed my compressor. It would start ok when the tank was empty but trip the breaker if it tried to start with pressure. Searched and read about weak caps, or problem with check valve or pressure switch leaving pressure in the pump head, etc. Turned out that the black plastic box which holds the 2 start up caps and is attached to the end of the motor with 2 screws had cracked on the bottom. The black box had tilted out enough that the start up caps switch was not engaging. Pushed on the lower part of the box and it started perfectly. Fixed it for the cost of some 2 part epoxy. Maybe not your fail, but definitely worth checking out first.

Broken reed valves- assuming the regulator is adjusted to maximum air pressure.These are located on the face of the pistons and require partial disassembly of the compressor head to serivce.When installing the new ones, add a drop of light duty thread locking compound to the threads to insure the screws do not fall out in use.

i would look at the head gasket

More then likely it is either in the valve plate (bad flapper valve or gasket) or the piston and sleeve have worn out which is usually from scoring. You will see that when you take the head off to inspect.

I would check the capacitor since it appears that the motor is not locked up. Here is a how to on testing capacitors;how-to-check-capacitor

I would think that is is actually coming from the crankshaft seal and running down. Does it leak when you are not using it, or just when it is being used? If it leaks even when it is not being used then it could be the drain plug. If it only leaks when being used then I would look at the crankshaft seal. And yes it would be very feasable to repair it, because like all things they don't make them like they used to.

Your tank check valve is stuck/broke. It's on the tank end of the line from the pump to the tank. It is supposed to close when the pump stops to keep air in the tank and let the system bleed pressure out of the pump so the motor can start when there is pressure in the tank. The part you need is CAC-437-2 and is available through searspartsdirect.com.

I just bought a few my self , try "Drillspot" good service and prices.

Don F

Hi,
This is usually a sign that the motor capacitor is bad.. and then it trips the overload...first thing to do is to replace the motor capacitor with a new one of identical rating...


heatman101