depends on wether the machine is a 2 cycle
or a 4 cycle
on a 2 cycle yes it is the same
on a 4 cycle you have oil rings
below the compression rings

Most oilless compressor or most porter cable do have brushes. But it sounds like your check valve is leaking. next time turn it on and leave for a minute then try to turn it back on. If it struggles or pops breaker that's the problem.

Any more ? just post. I've fixed over 100 of the same model and type.

thanks for the reply
I proved that it was the check valve in the following manner:
1. I let the compressor fill to maximum pressure.
2. I unplugged it.
3. Then manually I tripped the pressure switch to release the pressure in the head.
4. When I noticed that the pressure continued to bleed for minutes at a time, and that the pressure in the tank was dropping, I knew the check valve wasn't doing it's job.

I await a new valve, confident it will solve the problem.

Hi, Yes your capacitor is most likely the problem.The only other thing that could make it do that would be if the unloader valve was not working right. once the compressor pumps up and shuts off you should hear a short hiss as it dumps the pressure of the head.Hope that helps.Good luck.
Tinker

This could also be an issue with the check valve that is between the tank and the cylinder. When the check valve fails it allows the pressurized air from the tank to bleed back to the cylinder. The motor usually can't overcome this pressure when it turns back on.

Good luck,

-UtahAV
-Mark

thanks guys
I don't see a check valve, if there is one it must be part of the valve plate, which is new.
The unloader valve is in the pressure switch, again it's new.
I replaced the start capacitor even tho' it tested ok...no change in performance.
could there be a problem with the motor?
I bought this in '07...
It does start and run fine some of the time, but does labor regularly.

What is the type number of your compressor? (located on the same tag as the model number) The check valve for the type zero appears to be discontinued. The Check valve for the Type #1 and #2 is part #A19996. On the parts diagrams for all of the types the check valve is item #13. I really think that it is the problem. I just hope that your machine is not the type zero.

I hope this helps,

-UtahAV
-Mark

Mark-
thanks so much. I was thinking I would have to replace the motor.
this part seems to be almost hidden to any one not knowing it's there.
I'll order this today and hope it fixes the problem.
I thought too, that the pressure wasn't releasing, but thought the check valve was part of the pressure switch...
thanks again
~Dan

I went down to the shop and took the check valve out.
To my surprise, there was a small chip of stainless steel (from the old valve plate) stuck in it.
I removed the chip, sprayed it with a light lubricant and put it back in the compressor.
The compressor cycled 20 times with no problems....
glad to have the internet, and especially please to have this forum...

Hello kdav,

I would suspect that the piston ring and cylinder are worn. Not allowing pressure pressure build up. Part number K-0650 should take care of your problem.

Hope this helps,
-WJA

Hi John,

The ring is no longer offered as a separate part from the manufacture. They do still offer a piston and cylinder kit which includes the ring. If there was damage to the ring the cylinder likely needs to be replaced as well. The kit is part #KK-4835 and is available from http://ereplacementparts.com.

Good luck with your repair!

-Mark

Hi hunt,

The Type number is used by manufactures as a way to signify that an update has been made to a tool. The Type number on your P.C. C3151 air compressor will be listed on the tag with the model and serial numbers. If it doesn't have a Type listed anywhere on the tag then you can usually safely assume that you have the Type 0 machine. The Type 0 would be the initial version that the manufacture offered before any changes where made.

Hope this answers your question!

-Mark

Hey bowhunter84,
Manufactures sometimes make major changes and sometimes minor or no changes between types..if you don't have any type on your machine it probably is a type 0..also check to see if there is a part # change or not to the specific part [between types] that you need and match up with the picture if available.:)
hope this is helpful?
cmoorejack

Hey ggarrett,
Usually the check valve replacement remedies this problem..A19996 [the check valve lets air into tank but not back out..when it leaks, air pressure stays in the head of the pump and bogs down upon restart.] It sounds like you may still have pressure remaining in the head of the pump and it is not 'bleeding' off..check the tube and fitting going to the pressure switch for kinks or some kind problem..[make sure the pressure relief valve on the p switch is lined up straight..]
hope this helps..?
cmoorejack

reworked the check value and pressure switch, but the problem remains. Gave up and dropped it off at a repair shop.

Were you able to get it repaired and what was it? I did the check valve/pressure switch/scratch my head routine too.
Thanks

I agree with cmoorejack

I would check the air line that goes to the pressure and make sure the pressure switch is bleading the pressure off when the switch shuts off. You should hear a ppppsssssssssssss noise for a few seconds after the motor shuts off.

Sometimes the connection gets bent when installing the switch. Make sure the lever on the pressure relief valve pushes on the little pin.

My checklist is

Check Valve
Pressure Switch
Relief Valve
Trash Can

I am in the US Navy and am deployed right now. We had the same problem with three of our compressors and no one could figure it out. But the problem was so simple. I took the gauge from the P-switch and replaced it with a plug. That fixed the problem for now. I am pretty sure that with another gauge it will run pretty good but it seems to be working fine now. I have been using a nail gun now for 6 hours straight and have not had a problem with it. Any questions just let me know

Thanks bec98x and raiderfan. Not check valve, compensator tube, press switch or relief valve so far. In the meantime I took the capacitors (one apparently helps the motor re-start under load, and the other balances the running- that's what the motor guys says) out of the motor cover to a local shop and both read dead. I ordered replacements, probably wasting $$ since I remember that the gauge is bad on the PSwitch (reads 0 fully pumped) and I can't plug and test it until I can run the motor again. I'll keep you informed...somebody may benefit from this post thread since it seems that this is a common issue with this unit.

Would like to hear what turned out to be the problem on both ggarrett and bbeef's compressors? My compressor starts slow when empty then speeds up and runs fine, then just boggs down and throws the breaker on its second fill. Don't see how putting a plug in the guage hole is gonna fix that, my check valve is fine, pressure switch tube is fine, switch hisses at turn off like its suppossed too. Pressure switch conections are looking black from arcing while in "bogg mode", I'm thinking its a capacitor problem? Help please!

Figured it out, was the Start Capacitor inside the motor. I melted it from running the compressor on too long of extension cord, the motor never got to full speed and the start cap stayed in charge mode and cooked. Porter cables $98 for the capacitor kit is a little over priced. Individual Capacitors can be bought for $5-$12 just about anywhere. (McMaster, Grainger, motor shop)

its simple replace your capasitors, its a extra juse to start your motor i see this alot! its like puting a hard start kit in yor ac

Hey edmoe,
It could be the regulator ..if the air compressor pumps up and shuts off ok..its the regulator [unless your gauge is bad.. if you can tell your getting the full pressure out and it still reads low]..part # Z-A13369 reg assembly available at ereplacementparts.com...:) as far as the air leaking out as it sits..you can use a soapy solution in a spray bottle to check fittings etc for air leaks..
Hope this helps..:)
Craig

Thanks cmoorejack. The regulator seems to turn down o.k. but doesn't go high. I have the same problen with a pancake compressor.

what i had on one was the compressor wouldnt turn off or go past 60 some lil metal diaphram thing was broke had it repaired 40$ on my regulator problem if it dont pump up past 60 i open the lil black box and adjust limit scews to get it up to about start 80 - 120 kick off very dangerous thing too do could blow tank if u dont adjust correctly

Where was the "lil metal diaphram"?