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Fixing An Air Pressure Regulator
Fixing an air regulator offers it’s own challenges, for sure. I am very happy to extend from all of us thanks to Ed Parks for these instructions on fixing an air regulator.
It is very kind of him to take the time to put this down and send it to me for inclusion on this site. Here are Ed’s instructions.
If you’re trying to fix your air compressor, or you’re wondering how to fix an air compressor problem that you’re having – check out my air compressor troubleshooting page for a detailed list of common air compressor problems and links to handy guides on how to solve your air compressor problems!
Step by Step Guide to Fix An Air Pressure Regulator
Step-by-Step Instructions to Repair Air Compressor with a faulty regulator that does not allow adequate air pressure to come out of air hose.
Steps to fix an air pressure regulator on an air compressor:
- Confirm the diagnosis of a broken air pressure regulator
- Keep some pressure in the tank and prepare for disassembly
- Make sure compressor is unplugged
- Release all of the pressure from the tank
- Remove screws holding cowling / compressor cover
- Lay cover to one side don’t disconnect wires
- Remove air pressure regulator with wrench
- Remove air compressor regulator knob
- Remove pressure regulator knob control piston
- Remove piston spring from inside air regultor knob
- Twist air regulator knob to prepare for reassembly
- Apply lubricant to cylinder walls
- Reassemble the air pressure regulator knob
- Unscrew brass tank pressure seal assembly
- Clean pressure regulator manifold
- Clean the spring and rubber seat
- Grind the rubber seat
- Review the rubber seat
- Reassemble rubber seat, spring and brass tank pressure seal assembly
- Reassemble and tighten the brass assembly into manifold
- Reassemble regulator control knob assembly
- Reassemble plastic cover onto compressor
1 – Confirm the diagnosis of a broken air pressure regulator.
When the air compressor tank has plenty of air but you only get a short burst of air pressure (only momentarily) out of air hose and compressor’s air hose gauge goes to zero – the compressor regulator is likely faulty.
2 – Keep some pressure in the tank and prepare for disassembly
Be sure tank is not empty and has some pressure in tank. Turn Regulator Control Knob counter-clockwise all the way and release all pressure from air hose connector. The air pressure in the tank forces the Control Knob’s plastic piston to move back into the Control Knob/Regulator’s housing thus preventing damage to the plastic piston when disassembling.
3 – Make sure compressor is unplugged
Safety first! Make sure you unplug the compressor, as we’re going to be dealing with some exposed wiring.
4 – Release all of the pressure from the tank
Now release all air pressure from tank using the water drain valve on bottom of tank.
5 – Remove screws holding cowling / compressor cover
5Remove (6) screws holding top half of plastic compressor cover on: (2) from handle and (1) at each corner of plastic housing cover. The (2) screws in the handle are Machine Screws 10-32 x 1″ Phillips and most likely will strip when reassembled – replace with 10-32 x 1 1/4″ Phillips.
6 – Lay cover to one side don’t disconnect wires
Lay top half of plastic cover over to side – no need to disconnect any wires.
7 – Remove air pressure regulator with wrench
Remove air pressure regulator by using Crescent Wrench and turning hex nut counter-clockwise. Will be tight but be gentle so as not to damage o-ring seal. There will be just enough room to get wrench on at an angle with bottom plastic housing still in place when the Control Knob is completely screwed out.
8 – Remove air compressor regulator knob
Regulator Control Knob removed.
9 – Remove pressure regulator knob control piston
Turn the red Control Knob clockwise and the plastic piston with post in the middle (in above picture 5) will be pushed out.
10 – Remove piston spring from inside air regultor knob
Remove plastic piston, compression spring, and metal disk from Control Knob housing and clean all parts with a paper towel or rag; don’t use anything in housing that will scratch inner wall of cylinder, but clean out any corrosion. Do not remove the (2) o-rings from the plastic piston unless you plan to replace them.
11- Twist air regulator knob to prepare for reassembly
Turn red Control Knob counter-clockwise again to screw knob out for reassembling.
12 – Apply lubricant to cylinder walls
Apply a thin film of lubricant (would not recommend grease as it will gum up with time) – Teflon or Silicon lubricant or o-ring grease to the cylinder walls of the control knob’s housing, to the metal disk, and to the o-rings.
13 – Reassemble the air pressure regulator knob
Reassemble the above parts. Be sure the metal disk’s cupped side is facing to the bottom / inside of the Control Knob. It is easier to get these parts reassembled if you hold the parts as pictured below (on the crescent wrench) in your hand and place the Control Knob on top of them pressing them into the Control Knob housing carefully, not to damage the o-rings. Press in until completely seated like in picture 5. Sit reassembled Control Knob aside until final assembly.
14 – Unscrew brass tank pressure seal assembly
With a large flat screwdriver unscrew brass tank pressure seal assembly. Do not remove o-ring unless you plan on replacing it.
15 – Clean pressure regulator manifold
Clean inside of manifold with a paper towel or rag.
16 – Clean the spring and rubber seat
The part causing the problem is the rubber Tank Pressure Seat. Carefully remove the spring with it’s rubber seat, clean both parts. What has happened, due to the type of material, from pressure and moisture the rubber has swelled to the extent that an adequate amount of air cannot pass around the sides of the rubber seat. No need to remove the rubber seat from the compression spring.
17 – Grind the rubber seat
Using a Dremel with a 1/8″ round carbide bit carefully grind a notch into the (4) sides (the center of the sides only, not the corners) of the rubber seat. BE VERY CAREFUL NOT TO GRIND TO DEEP.
Upon close inspection of the sealing surface of the rubber seat you’ll notice a circular groove that makes contact with the sealing / mating surface inside of the brass threaded hex bushing. Be sure to not grind any where close to this sealing groove in the rubber or your tank will no longer hold pressure when stored. Do Not Grind on the corners at all; the corners keep the rubber seat in place and aligned in the brass hex bushing.
18 – Review the rubber seat
Notice depth of the notches is just enough to create a gap for air to come around the rubber when it is reassembled in the brass threaded hex bushing.
19 – Reassemble rubber seat, spring and brass tank pressure seal assembly
Apply a very thin film of Teflon or Silicon lube or o-ring grease to the rubber and reassembly into brass threaded hex bushing.
20 – Reassemble and tighten the brass assembly into manifold
Apply a light coating of lubricant to the o-ring and screw brass assembly into manifold. Just tighten snugly – no need to overly tighten o-ring seals -, just good and snug (to tight will cut o-ring).
21 – Reassemble regulator control knob assembly
Apply a coating of lubricant to the Regulator Control Knob assembly’s o-ring and also to it’s mating surface of the manifold. This o-ring will be fairly easy to cut if not careful. Reassemble Regulator Control Knob assembly into manifold, again tighten snugly, but don’t over do.
22 – Reassemble plastic cover onto compressor
Reassemble top half of plastic cover to compressor.
This fix will now allow an adequate amount of air to pass around the rubber seat that had swelled over time.
If someone can locate a part number and a source for a new rubber seat please post it on the parts needed page, and refer to this page too, if you would.
Thank you so much for your repair instructions about how to fix a regulator on the page https://www.about-air-compressors.com/fixing-an-air-regulator. Now my Central Pneumatic 3-gallon pancake air compressor, model 95275, from Harbor Freight is working again. Yippee! I didn’t have the proper lubricant, so all I did was disassemble it, and used my Dremel to shave off bits of the rubber Tank Pressure Seat, as you showed. I wasn’t sure what you meant about the “corners”, since it was perfectly round, but I just shaved off a little from the four points of a cross, reassembled it, and now it releases air again. Before, it would only do one brief puff of air, and then the regulator pressure gauge would bottom out at zero, and have no more pressure, even though the tank was fully pressurized.
Note added: I didn’t have a screwdriver big enough to remove the Tank Pressure Seal, but a socket wrench worked very well. Putting it together, I just needed to push down on the head of the Tank Pressure Seal to compress the spring and start threading it in a little by hand, and then I could use the socket wrench to tighten it the rest of the way.
Fixed now, thanks to you! You have a very informative site, and I greatly appreciate your work.
Response: Well Dave, the originator of these instructions was Ed Parks, and we would very much like to send him your comment but have no way of reaching him. I hope he reads your kind words. Cheers!