Air compressor won't build pressure

   / Air compressor won't build pressure #1  
Iplayfarmer

Iplayfarmer

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Massey Ferguson 1215, Case 801B
I got a used Harbor Freight compressor from a guy locally. It won't build pressure past 40 PSI. I'm suspecting that the guy let it run out of oil or ran it too hard and burned the rings.

I'd like some input from the forum here, though. What's likely to cause this? Anyone had experience getting parts from Harbor Freight? Is it pretty easy?

How would I do an overhaul if it is burnt rings? Do I have to hone the cylinder and put in oversize rings?

Any input would be useful. I know that these Harbor Freight things are pretty cheap, but if I can put a few dollars and a little time into this compressor and get it running again, it will be well worth it.
 
   / Air compressor won't build pressure #2  
You'll probably spend more money trying to fix it than you would going and buying a new one.
 
   / Air compressor won't build pressure #3  
Is the pressure regulator cutting it off at 40 psi or does it keep running, but never gets past 40 psi? Have any leaks?

Would hate to invest much in HF compressor.
 
   / Air compressor won't build pressure
  • Thread Starter
#5  
   / Air compressor won't build pressure #6  
Well either the piston/cylinder is not sealing properly, or the check valve is not sealing properly. There are several ways these are put together. If the compressor is compressing any air, the piston is moving air, so it now becomes a matter of where that air is going. One quick check is to put your hand over the air intake and see if there is any air being puffed back out the filter when the compressor reaches 40 PSI. A little smoke can help visualize this. If there is, it is the check/flapper valve plate. Does this compressor have a crankcase vent? IS there any air comming out of this vent? If so, that would indicate worn pinstn/cylinder seal. Any air leaking from anywhere else? Apply some bubble mix to all the fittings...
 
   / Air compressor won't build pressure
  • Thread Starter
#7  
RonMar said:
One quick check is to put your hand over the air intake and see if there is any air being puffed back out the filter when the compressor reaches 40 PSI. A little smoke can help visualize this. If there is, it is the check/flapper valve plate. Does this compressor have a crankcase vent? IS there any air comming out of this vent? If so, that would indicate worn pinstn/cylinder seal. Any air leaking from anywhere else? Apply some bubble mix to all the fittings...
Click to expand...

I got overambitious and already tore into it. So, it's a little hard to check for air leaks now. before I tore it apart, though, I did pressure it up to 40 PSI and it held pressure for at least the 3 hours I let it sit before I took it apart. That eliminates a bunch of the leak possibilities.

I had to get some red RTV for another project. I won't use the whole can, so I'm going to try some on this compressor. Worst case scenario it will still not build pressure, and then I will be in the same boat I am now with very little time or expense wasted.
 
   / Air compressor won't build pressure
  • Thread Starter
#8  
Drum Roll Please...

Tadaaa!! I fixed it!!

Thanks in a large part to the advice and input from all you knowledgeable and supportive folks here on TBN.

All I did was cleaned the surfaces of everything including the spring steel valves and applied a coat of red RTV to everything. I let it sit for a little while and then fired it up.

Almost 120 PSI before the pressure switch shut it off.

As a post script, I didn't wait long enough for the red stuff to cure, so I now have little red bits of silicone sprayed all over the immediate vicinity of the compressor. I took it apart and cleaned all the surfaces again. I applied an much smaller amount of silicone this time, and I am writing this post during the 10 minutes that the sealant needs to "skin over" before I put the pieces back together again.

I plan to tighten everything down to finger tight tonight and then tighten it all the way after it cures overnight.
 
   / Air compressor won't build pressure #9  
Thanks for the update. It helps all us armchair mechanics learn something.:D
 
   / Air compressor won't build pressure #10  
I wish i had got to you first before you used the red goo. I just redid mine last week.

I had a harbor freight pancake compressor that did the same thing.. built 40 psi.. no more.. turne dout it was bad gaskets.. I used generic gasket paper and put it back together dry.. runs perfect.

That gasket goo may dislodge and give you problems.. at least in one area, the clearances are kinda wide on the castings.. not having a solid gasket to clamp to may let the gasket move and blow out.

In any event.. you now know how easy it is to get back into.. so if you do have to remake the gaskets.. it's not much time lost..

soundguy



Iplayfarmer said:
Drum Roll Please...

Tadaaa!! I fixed it!!

Thanks in a large part to the advice and input from all you knowledgeable and supportive folks here on TBN.

All I did was cleaned the surfaces of everything including the spring steel valves and applied a coat of red RTV to everything. I let it sit for a little while and then fired it up.

Almost 120 PSI before the pressure switch shut it off.

As a post script, I didn't wait long enough for the red stuff to cure, so I now have little red bits of silicone sprayed all over the immediate vicinity of the compressor. I took it apart and cleaned all the surfaces again. I applied an much smaller amount of silicone this time, and I am writing this post during the 10 minutes that the sealant needs to "skin over" before I put the pieces back together again.

I plan to tighten everything down to finger tight tonight and then tighten it all the way after it cures overnight.
Click to expand...
 
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