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hhp_Tech
hhp_Tech, Technician
Category: Small Engine
Satisfied Customers: 193
Experience:  20+ Years in Industry - High Performance Technician - All around Enthusiast
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My Craftsman 3 gallon/1 HP portable air compressor model#921.153101

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My Craftsman 3 gallon/1 HP portable air compressor model#921.153101 will not go above 20# XXXXX in tank.
The unit is only 2 years old and very little use.I would like to fix it myself because if I took it to Sears for repair the cost would not be worth what I paid for the compressor.The tank does hold the 20# XXXXX air when I shut it off so I ruled out an air leak.

hhp_Tech :

Hi, if adjusting the regulator does nothing and it had no leaks the next thing is to pull the head and inspect the pressure plate and reed system

Pressure plate rebuild parts are about $25





remove the 4 bolts holding the head on top of the cylinder.
Remove the head.


Directly under the head is the pressure plate.

The pressure plate reeds keep the air from going back through the intake side of the compressor.
Check the reeds for warping or breaking.

If the reeds are damaged, you must replace the pressure plate with it.

Make good notes of how the pressure plate sets and the o-rings that seal around it.


Remove the pressure plate and inspect the cylinder walls for scratches or wear, if the cylinder is damaged you need to replace the cylinder, piston, and rings.

Piston/ring/rod rebuild kit $35

If a ring is worn or broken the air goes back through the intake filter and no pressure is built.
If you have to replace the rings, I would replace the piston and sleeve too.


If you do not feel confident repairing this problem yourself that is fine but I wanted to offer up at least how and what to inspect.




here is the breakdown of parts

Click here

Parts can be bought from sears parts direct website


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