My air compressor a, 2 stage is over heating on the one cylinder that is the 2nd in line to the tank change the oil checked the filters and has good ventilation. One of the cylinder`s hotter than the other one

ASSUMING THIS IS AN ELECTRIC MOTOR DRIVEN SINGLE STAGE COMPRESSOR, IF THE COMPRESSOR USES OIL IN THE CRANKCASE, THE PRESSURE SWITCH SHOULD CUT OFF AT 125 PSI AS THE ACT OF COMPRESSION HEATS THE AIR QUITE HOT. THERE IS ALWAYS SOME OIL THAT PASSED THE PISTON RINGS IN THE COMPRESSED AIR. IF THE COMPRESSED AIR GETS HOT ENOUGH, THE OIL VAPOR CAN IGNITE AND THE FLAME CAN CARRY TO THE TANK FOR AN IMPRESSIVE EXPLOSION. THIS ORDINARILY DOES NOT HAPPEN BELOW 175PSI OR MORE.

OILLESS COMPRESSORS CAN BE SET TO 150 PSI. WITH EITHER TYPE OF COMPRESSOR, THE HOSE SHOULD BE ATTACHED TO THE REGULATOR OR THE REGULATOR STACK, NEVER TO THE COMPRESSOR, AS THE COMPRESSED AIR LOSES MUCH OF ITS HEAT WHILE IN THE RECEIVER. IF THE WHOLE TANK IS GETTING HOT ENOUGH TO MELT A PROPERLY ATTACHED HOSE, YOU HAVE A DANGEROUS SITUATION, CHECK THE OPERATION OF THE PRESSURE SWITCH, UNLOADER VALVE AND RELIEF VALVE. THE RELIEF VALVE SHOULD OPEN AT NO MORE THAN 150 PSI, THE UNLOADER VALVE OPENS WHEN THE PRESSURE SWITCH SHUTS THE MOTOR OFF, AND SHOULD ONLY HISS FOR A FEW SECONDS AS IT DUMPS THE PRESSURE ONLY IN THE COMPRESSOR AND THE LINE FROM THE COMPRESSOR TO THE TANK INLET CHECK VALVE. IF THE UNLOADER VALVE HISSES MORE THAN A FEW SECONDS, THE TANK INLET CHECK VALVE IS LEAKING AND NEEDS TO BE SERVICED, CLEANED OR REPLACED. IF THERE IS CARBON BUILD UP IN THE VALVE, THERE IS EXCESS OIL PASSING THE COMPRESSOR PISTON RINGS, REPLACING THEM MIGHT FIX THAT IF THE CYLINDER OR RING LANDS ON THE PISTON ARE NOT TOO TAPERED OR WORN.

1st ck to see that the internal cooling fan is running
2nd ck to see that air/oil heat exchanger is not plugged off with dust
3rd make sure machine has proper oil level as provided by sump level gauge , this should be ck'd while running as oil level will drop as machine is running .

if all these conditons are good , there can be only two other problems to cause this (1) outlet pressure setpoint too great
(2) air/oil heat exchanger has internal blockages

The motor will run until the pressure switch detects approximately 150psi in the tank. If it never gets to 150psi, it will continue to run. If you are not getting over 50psi in the tank check:
1. that the drain valve on bottom of the tank is fully closed. Don't use a wrench on it but it must be tightly closed by hand.
2. that you don't have any air leaks on the top end of the compressor or on your lines going out of the tank.
If these are OK, your problem lies either in a damaged valve plate or cylinder/piston. You can remove the head and check the condition of both the cylinders and the valve plate. All reeds on the valve plate have to be in good condition with no bends, cracks or warpage from over heating or debris from using the compressor with no air filter. The cylinders should be smooth with no scaring. If a cylinder is damaged you will have to also replace the rings or piston assembly. None of the air compressor companies make an oversized ring set so you can lightly hone cylinders but you cannot have them bored out oversized to correct any damage to the cylinder walls.

YOU MAY HAVE TO REPLACE YOUR REED PLATE AND OR YOUR PISTON AND RING AND CYLINDER.YOU CAN FIND THE PARTS RIGHT AT SEAR WEB SITE

I will need more info on this. What is the model of compressor. Is it oil free or a 2 stage oil flooded. From the info provided it sounds like an oil free unit. These units have alarms for 1st and 2nd stages. Suggest inspecting the discharge check valve with out more info.

Problem sounds like valve plate /reed valves or worn cylinder /vinyl ring. Easy to check, push piston to top position and examine cylinder neer top looking for scratches. If scratched, most likely vinyl piston ring/s are worn and allowing pressure to leak past. If cylinders look good /shiney all the way up to top, remove head/s and examine reed plate/s for missing/broken reeds and or torn gasket/s. If your reed plate is missing one reed and your are good at being creative, you can seal individual hole by threading and plugging with thin piece of bolt. Good luck and good holidays

You suspect this unit as being a two stage because of the unusually high cut off pressure. It is a single stage and the motor really has a difficult task and is being pushed to the limits. to reach this pressure. We usually reset the pressure to lower setting ~~ say around 140. Your pump probably has a leaking intank check valve (brass fitting at tank) or leaking valve plate in pump. Simple tests : with pressure in tank unplug compressor from outlet and listens for air leak around pressure switch. As you unplug the running compressor from outlet you should hear air leaking from pressure switch for just a moment as air is let out of airline from pump to tank. If air leaks out till zero pressure then change the valve. If tank holds pressure then valve probably ok. Next test, with no air in tank and air filter removed, plug in compressor and feel intake port for strong suction. If the valve plate is bad, suction will decrease as pressure neers the 120 mark till the point of feeling that air is actually blowing out of intake. With good valve plate there will be strong suction untill unit reaches set pressure. If valve plate is bad also change the cylinder and piston ring. Good luck with your repair.

The compressor should pump into a final check valve where the pressure switch is located. Check the condition of that valve. If the compressor itself is not pumping, the cylinder heads need to be removed and the valves in each head checked. Check the condition of the cylinder walls which should be smooth without any lengthwise grooves. Is the tank rusted through? Any leaking safety valves? Make sure you have proper oil level in the crankcase. Make sure the intake filter is clean. Check the tubes between the cylinders and the tank for leakage (splits or rust throughs). Just work from intake to tank in a progression, checking output at each point.

hi is your machine reaching full pressure? if so maybe your problem is with your tool?