20 Most Recent Hitachi EC12 Portable Electric 2hp Air Compressor, Oil Lubricated - Page 4 Questions & Answers

SAE 5W50 and if available use full synthetic.

This link will take you to the EC12 owners manual if you would like.

http://www.hitachipowertools.com/product/files/pneumatics/compressors/EC12__OM.pdf

You are correct in suspecting the regulator. Easy fix however. Remove the safety pop valve and install a tee fitting. Reinstall the safety on one port and install a quick-connect fitting on the other port. Now you will have access to full tank pressure when you need full power. In the process of regulating pressure, the 1/4 inch port size adjustable regulator will restrict the air volume. A 3/8 port size (larger air regulator ) is less volume restricting however more expensive. You can install a 3/8 port size regulator on your compressor in place of the small one installed now. Other possible trouble areas are too small inside diameter air hose , too long of a hose and air hose that has inner liner torn and is restricting airflow. Good luck

Usually, oil at the fill plug indicates too much oil in the crankcase. Fill to top of notch cut into dipstick. The dipstick should have two orings that seal in oil and makes for firm fit into body of compressor. If oil and dipstick are ok, then suspect compressed air leaking past rings. Remove cylinder with head attached to check condition of cylinder / piston/ rings. Easy fix and low prices on parts. Go to www.toolpartsdirect.com Good luck

It can be some mist between valves.

If you are getting the same pressure on the outlet side of the regulator as you have in the tank, regardless of where you set the regulator knob, it's possible you have the regulator on backwards. The inlet and outlet on the regulator are on opposing sided and the third hole is for the output gage. Try turning the regulator around. If that doesn't fix the problem, it is possible you got a bad replacement.

Your infeed valve is stuck/broke in the open position. As you are looking at the motor/pump side of the compressor, on the right side of the top tank there is a brass valve that has leading into it a copper tube from the pump and the small black tube from the pressure switch. This valve lets air into the tank from the pump but should close when the pump turns off. When the motor turns off the black tube lets air bleed out of the pump and copper line so the motor can turn over when the pressure switch turns it on again. You need to contact Hitachi or one of their service centers to find out which infeed valve you need, they ahve different part numbers depending on what year your compressor was made. Go to http://www.hitachipowertools.com/index.aspx and use either their contact us page or the search for your nearest service center page and they should be able to tell you what part number you need.

There should be a pressure regulator set to a certain psi make sure it is not set too low or the pop valve will release the remaining air for safety.

Pull the dipstick and notice the notch cut into both sides at bottom (push dipstick all the way in to check oil level). Fill to top of notch. Lowest safe oil level is bottom of notch. This unit does not hold much oil. Always use the compressor on level ground (tilted compressor could cause a lack of lubrication). Good luck

With no air in the tank and amp meter connected to one leg of line, start compressor and note amp draw thru cycle. It should draw low amps at first then reach rated amp draw close to end of cycle(most likely 12-15 amps). If amp draw is normal then replace thermal breaker. Older compressors have thermal breaker incorporated within winding and may not be easily replaced (but not impossible). If amp draw is higher than rated, check capacitor for proper rating and make sure that the in-tank check valve is not leaking pressure back to pump. Good holidays

This compressor draws too much power to run efficiently with an extension cord, however, sometimes one does not have a choice. For best results, connect directly to outlet. The problem that you describe could be caused by the extension cord or the check valve leaking air which in turn loads the pump making it difficult for the motor to start. Easy test. With air in tank (+100pse) remove air line at the checkvalve and test for leak with soapy water. If leaking, replace valve to solve problem of "grunt mode." If no leak and connected directly to plug with same problem, test start/run capacitor for proper valve. It should measure within 95% of printed value. Parts are available at www.toolpartsdirect.com . Good holidays

Hitachi EC12 Air Compressor Parts : MASTERTOOLREPAIR.COM

Here is a site that says:
1. Are the capacitors good? (They get the motor going).
2. If they are, replace the stator, ($245)

If you don't find a good solution there, I would try taking it to a local motor rebuilder.
Gary

Failed capacitor will result in problem as you describe. Remove capacitor and have test. It should read/measure to 95% of stated valve. If cap test good, remove rear cover and manually turn fan. If frozen of hard to turn, drain oil and remove cylinder where it is attached to body and pull it off. From here you will be able to examine the piston, rod and crank. Good holidays.

Hello,

Yes you can use synthetic oil in you compressor. Emglo just has their name on it. Its ok to use.

Hope this helps, Matt If you need further help, I’m available over the phone at https://www.6ya.com/expert/matt_8dbc24bf722649ac

Try at eReplacementParts.com : Power Tool Parts and Tool Repair Diagrams.

If you need more help come back.Post / thumbs / testimonial are welcome!

DEPENDING HOW OLD IS YOUR MACHINE IT WILL START COMMON LEAKS DUE TO HARD WEAR, BUT YOU CAN FIX IT IF YOU DO A MOTOR OVERHAUL BEFORE MORE WEAR AND MORE MONEY TO SPEND TO REPAIR.

Are you hooking within 5ft of the outlet? If you are running a cord, then the cord can't keep the amp rating needed to run the compressor. I have one that does the exact thing. Try plugging it in close.

It souds like a sticky "non return valve". See the fix below.
The non return valve is the chrome part with a hex cap adjacent to the upper tank. Remove the cap and make sure the piston moves freely. Slight resistance is ok, but if it sticks your compressor willl continually blow off air.

The check valve or "non return valve", as listed in the Hitachi parts manual is definitely the culprit here, but there is an alternative solution to replacing the entire valve that was actually suggested to me by a Hitachi Tech when I stopped by my local service center to pick up a new non return valve. Obviously, the rubber piston swells and sticks to the point that the spring under the piston can't over come the friction. I removed the piston and carefully reduced its diameter, by hand, with varying grades of wet or dry paper and it now operates perfectly. If one is uncomfortable with such a repair, at least keep it in mind for a quick jobsite fix. I have now been running my repaired compressor for several months without issue.

Running compressor without out oil generally will damage rod and deposit metal on crank lobe. Metal can be removed using 400 grit sandpaper cut into one inch strips pulling back and fourth untill lobe is clean as new. You will only need to buy the rod(about $20) and one sheet paper. Remove pump/motor from frame, remove two bolts holding cylinder to body and airline and pull up on cylinder to expose piston/rod. Usually the rod will slightly coat the crank with metal and seize. Remove or work rod off lobe. Clean crank area and add fresh oil. Parts available at www.toolpartsdirect.com Good luck

When the unloader leaks as you describe indicates that the check valve is leaking. Easy to check the condition of the valve. Follow air discharge line from compressor head to tank. The brass or steel fitting that threads into tank is the checkvalve. Remove all air from tank and remove large inspection cap to reveal the teflon seat. If it is cracked or swollen you will need to replace the valve. Parts available at www.toolpartsdirect.com Good luck