Frequently Asked Questions

  • How much oil does my compressor require when I change it?
    Most Bostitch portable oil lubricated compressors require approximately 6 to 7 ounces of oil; however, the only positive way to know if the unit is at appropriate levels is to use the dipstick provided with the compressor. All of the dipsticks have a distinct notch or marking for the max/min. at the BOTTOM of the dipstick to measure oil levels. If you do not have a dipstick, do not use the compressor. Call Stanley-Bostitch Customer Service at 800-556-6696 with the appropriate model number and one will be sent to you.
  • My compressor does not shut off; it continues to run and pump air and the safety relief valve leaks air very loudly.
    The pressure switch (on / off switch) must be adjusted or has failed. A qualified Bostitch Tecnician can determine if the switch can be adjusted or must be replaced.

    To locate a service center near you, click here.
  • How do I change the oil in my compressor?
    Most Stanley-Bostitch compressors - portable compressors have a small drain screw at the bottom / middle of the crankcase cover. The crankcase cover is the plate that the dipstick inserts into. To drain the oil, remove the drain screw and dipstick and allow the oil to drain until the oil no longer flows. (Most Stanley-Bostitch portable compressors have approximately 6 to 7 ounces of oil so this process will not take long). Replace the drain screw (be sure not to over-tighten) and add fresh oil in the top of the crankcase at the dipstick hole. Check the oil level with the dipstick often; it is full when the oil level reaches the notched area on the dipstick. If too much oil is added, it mut be drained to proper levels.
  • Does my compressor have to be on level ground when running?
    If you have an oil lubricated compressor, the compressor MUST be run on level ground at all times. The oil level in the crankcase is very low at normal levels and it is spread throughout the crankcase using splash pins located on the bottom of the connecting rods. If the compressor is not level, the splash pins can not reach the oil and the compressor pump components will heat up and seize. If you own an oil free compressor, it does not have to be on level ground.
  • How do I clear water that has built up in the bottom of the tank of my compressor?
    All compressors have drain valves at the bottom of the air tanks. These are used both for relieving pressure from the tanks at the end of the day, and to expel the water that builds up due to normal condensation. Allow the compressor to run up to top pressure and shut off automatically. In normal conditions, you may then shut the compressor switch off and open the drain valves. The air pressure that is released will carry excess water out of the tanks. (Note: Open these valves outside; as any rust or oil buildup will be expelled as well, and can cause staining to floors or carpets.) In extreme circumstances, where a lot of water has built up, leave the compressor switch on, so that it will kick on and and continue to pump pressure until the water stops draining. You may then turn the compressor switch off.
  • My compressor will not start when plugged into the electrical outlet.

    Check the power at the outlet; compressors require a 120V / 15Amp unloaded circuit to start properly. Check the tank pressure gauge; if the tank is already filled with compressed air, the pressure switch (on / off switch) will not activate because the pressure is above the recycle level. Check the pressure switch (on / off switch). To turn on most units, the red button is pulled up for on, and pushed down for off.

    To find a Factory Service Center in your area, please click here. 

  • My compressor pumps up to pressure and shuts off at the desired rating, but no air comes out of the airline to my tool. What is wrong?
    The air regulator / pressure reducer has failed. Replace it with a new one. The air regulator / pressure reducer is the last item coming off the tank that the hose connects to. It has a guage attached to it that should indicate the line pressure. Often when the regulator fails, it will initially read that it has pressure, but immediately drops to zero psi as soon as the hose or the tool is hooked up.
  • What will happen to my compressor if I add too much oil?
    Generally, no harm will come to the compressor, but oil will spray out of the dipstick in a mist. The dipstick is also a breather that allows normal back pressure to be relieved out of the crankcase. Excessive oil blowing back through the dipstick can cause damage to walls, floors, and carpeting if used indoors. It is recommended that oil lubricated compressors be used outdoors with hoses going inside whenever possible. It is normal to have some low level oil residue at the dipstick and crankcase cover even when the oil is at proper levels.
  • My compressor is difficult to start in cold weather. Can this be repaired?
    If the compresssor works well most of the time but will not start in cold temperatures, there is most likely nothing wrong with the unit. Just like automobiles, the moving parts are a little harder to move due to contraction of the metals combined with and much more importantly, the thickening of the lubricating oils. An SAE 30 weight oil that provides excellent protection in high heat can become as thick as molasses in the winter. Synthetic oils are far less affected by temperature extremes and provide easy starting in the winter and appropriate protection in the summer. We recommend synthetic 5W-50 oil.
  • My compressor runs but does not pump air into the tank. What's wrong?
    If it is a brand new compressor, be sure that all plastic shipping plugs are removed and replaced with the proper components, such as Oil Dipsticks or Air Filters. (This varies from model to model; some models will not require this step.) Be sure that the drain valves at the bottom of the tanks are closed. Check for leaks at all tubing connections and under the pressure switch (on / off switch). Pump components inside the pump, such as gaskets, valve plates, and pistons can cause this failure. A qualified Bostitch Technician should handle these repairs.

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  • My compressor and hoses fill with water that eventually gets into my air tools. Is there something wrong with my compressor?
    No. Water in the compressor tanks and hoses is a result of natural condensation that can then form into pools. The severity of the water buildup can vary greatly depending upon working conditions; specifically high humidity or cold temperatures. With humidity, the moist air passes through the pump, and the water will slowly collect at the bottom of the tanks. Cold temperatures are the most difficult. Cold air is drawn in through a very hot pump and heated. This hot air is then pumped through hundreds of feet of very cold hose to reach the tools. The result is excessive condensation inside the hoses that is carried on through the hose and settles in the air tools. During the downtime for the air tools, the water will pool in the low areas of the hose and freeze, causing severe air flow restrictions that will choke the tools. The water vapors that made it all the way to the air tool will freeze in the head valves and cause sluggish cycling. The compressor tanks and hoses should be drained several times per day in these conditions.
  • Can I use a spray painter with my Bostitch Compressor?
    This question can not be answered without knowing specifics. The only way to know is to compare the CFM (Cubic Feet Per Minute) capabilities of the individual compressor you are using and match that to the CFM requirements of the spray painter. Bostitch pneumatic nailers and staplers are very air efficient air tools and do not require high CFM in many applications. However, most spray painters require high levels of CFM to operate, even though they are low pressure (PSI) tools. The requirements usually exceed the capabilities of most small portable compressors. Compressors with larger tanks and pumps such as the wheel barrow type are often required.
  • My compressor only hums when it is turned on; it will not start.
    This often means that there is not enough power getting to the motor to start it. Check the power at the outlet, compressors require a 120V / 15Amp unloaded circuit to function properly. If at all possible, do not use extension cords. There is a significant current drop in long extension cords. If extension cords are absolutely necessary, refer to your Operators Manual for the proper extension cord lengths and proper wire gauges. Do not vary from these recommendations. Low current can cause extensive damage to the compressor motor. It is recommended that if you need to work a significant distance from the power supply, use longer hoses from the compressor to the air tool. Generators are not recommended for use with compressors. If the compressor starts okay at 0 psi and shuts off at its target pressure range, but will not restart and hums when you have approximately 95 psi, the unloader valve in the pressure switch or the check valve in the tank could be failing.
  • Can I run my Bostitch compressor from a generator?
    We do not recommend using a generator for compressors. The power supply fluctuates considerably -- especially if other power tools are being used at the same time that the compressor re-starts. This can cause severe damage to the compressor motor and can affect warranty coverage. However, if a generator must be used, be sure that the compressor is the only electrical device on the circuit and that the generator has a minimum output of 6500 watts.
  • Is it ok to run my compressor with the oil level low for a short period of time?
    No, the oil sits at the bottom of the crankcase and is "splashed" around the entire crankcase to lubricate the cylinder, piston, and connecting rod pivot points and bearings by pins at the bottom of the connecting rods. If the oil level is too low for the splash pins to reach the oil, severe damage will occur very quickly.
  • My compressor runs well, but it does not keep up to my tool like it used to. Does it need to be rebuilt?
    When a compressor takes longer to rebuild pressure, it can be a sign that the piston rings or cylinder are wearing. However, first check the intake filter. Dirty filters are the most common reason for slow pump up times. The restricted intake of air can also potentially create increased stress on the motor and cause it to overheat or ovrload circuit breakers. Clean or replace filters first.

    To find a Factory Service Center in your area, please click here. 
  • Air leaks from the drain valves on the bottom of the tanks of my compressor. Do I need to replace the drain valves?
    Most likely, the drain valves must replaced. However, contaminants can sometimes build up at valve seats that does not allow them to seal properly when closed. Attempt to clear the contaminants by allowing the compressor to reach top pressure and shut off automatically. Leave the switch at the ON position and open the drain valves fully; when the pressure drops, the compressor will restart; allow the compressor to run with the drains open for a few minutes. This will clear all loose particles in and around the drains, as well as all built-up fluids from condensation. If this fails to solve the leaks, the valves are damaged and must be replaced.