Sanborn air compressor leaks

I have an old Sanborn air compreesor that I tried to use.

I went to the Casey's Store and filled it with air, but it would only take 40 lbs. I tried to use it when I got it home, but I couldn't hear the air going into my car tire.

The tire went down 10 psi at this point. I turned the dial clockwise and counterwise but still never heard air escaping.

It was empty by the next morning. How do I get it to release air when I want?

Bill says....

A few issues here, I think, visitor.

When you say that it would only "take" 40 PSI, I am not sure what that means.

Does the compressor run? When it does run, do you mean that when the compressor is running, the tank pressure only goes up to 40 PSI?

What tire pressure are you trying to achieve? Compressed air flows from higher pressure to lower pressure. If your tire pressure is 40 PSI, and the tank pressure is 40 PSI, then in theory there will be no flow.

But, cheap air gauges are notoriously inaccurate. So, even though the gauge shows 40 PSI, it might only be 35 PSI in the tank, and if the tire had 40 PSI in it, air would flow from the tire back to the compressor tank.

Please provide more info as a comment here so we can help figure out what's going on with your Sanborn air compressor.



Comments for Sanborn air compressor leaks

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Sep 21, 2013
27 gal. compressor
by: Mike

Does anyone have this unit, I need the factory settings.Please help ( mgentille2002

Dec 27, 2011
air compressor
by: Anonymous

I've been told that the Casey's store air compressor used for filling up tires, etc. doesn't have enough pressure to fill a compressor. It rebuilds its pressure after someone uses it, but if too many people use it in a row, it wouldn't work either. I need to go to a place with a higher pressure and see what happens. Thanks.

Dec 26, 2011
Sanborn air compressor
by: Jan Dickson

I don't know what the pressure is. I just filled it at a Casey's Store and someone told me that they didn't have much pressure like a good service station would. But, the gauge to the compressor stopped rising when it reached 40 lbs. It goes up a lot higher than that though.

Dec 23, 2011
air compressor
by: jan dickson

The compressor stopped filling up with air when the gauge read 40 lbs. The compressor doesn't run. I just turned the dial and thought it would fill from the compressor to the tire. I want 38 psi in my tires so that might be the problem.


Still puzzled, Jan. You are using the Sanborn compressor as just an air storage tank, and the tank will only hold 40 PSI? Something wrong with that. When you were filling it, what was the pressure in the line you were using to fill the tank?

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Coleman Powermate Black Max slow to build pressure

by Len
(Idledale, Co)

I have two Coleman Powermate Black Max direct drive single stage oilless 5hp compressors (27 gal tank) model# BL0502710.

They both were slow to build pressure so I rebuilt one with a new piston/cylinder assembly and cleaned up the valve plate and reed valves which cut down the charge time from ~20 min to 7 min.

However, after about 2 weeks of moderate use the charge time is back to 18-20 min.

The reed valves seem to be in good shape, no bends or cracks, I replaced the gaskets and still the same story.

I also tried swapping the valve plate with the other compressor's and no change.

When the pump is running there seems to be a lot of air coming out of the front (piston side) of the pump. The air intake sucks in air fine and no blowback is apparent.

Also, there is daylight around the piston seal inside the cylinder through the whole stroke when turned by hand.

My thought is this gap in the cylinder is what is causing all the problems but shouldn't the air pressure inflate the seal on the upstroke? Is there something else I can check, or do you know a way to better test the valves to see if they are the issue?

Bill says....

Len, I don't know what this means... "When the pump is running there seems to be a lot of air coming out of the front (piston side) of the pump" Where is the air coming from, exactly.

Depending on the type of piston seal, some will "inflate" with pressure. However, that you can see daylight all the way around suggests to me that you need new piston seals.

That cleaning the valves improved things for a while suggest to me, too, that the valves are part of your problem. Cleaning them might not be enough.



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Nov 29, 2011
by: Anonymous

Where can I buy the parts to restore the unit?


I believe your compressor is made by:

Start with them.

Aug 22, 2011
Piston Cup
by: Anonymous

I am having the same "slow to build pressure" problem with my Coleman, it just doesn't put out like it used to. I think the "piston seal" or "piston cup" is worn out. I've heard that's what wears out on these oilless compressors...

Bill, Any ideas on where to find just replacement cups?
Ive been looking for a while and I really detest buying the whole assembly for $90.


I can't find any info on them to share with you. Maybe go to the Buy/Sell page and post that you want to buy one for parts? And, of course, go to the parts wanted page and post there too.


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