Bostitch Compressor not building air

[Jlanman4]

Hey guys, I’m new to the site but hoping to get some advice on an air compressor I just bought. It’s an older Bostitch 6 gallon 150 psi compressor.

Seems to run fine, but it does not build air pressure beyond maybe 20 psi. Im hoping to get an idea of how to troubleshoot this thing. I don’t know much about these things so I’m not very familiar with all the parts.

I took the housing off and noticed this tube was not connected and looks like it has a hole in the side as well. Could this be the issue?

I’m also not wanting to put any money into it, so if it’s gonna need major service or parts, I may just invest in a brand new one for like $100. But any advice is greatly appreciated.

 

[The Cobbler]

take a picture of the tube you speak of.
sounds like a small leak somewhere, or the piston ring is worn

 

[NeubCont]

Welcome to GJ
Great info and stuff here!
Pictures always help here on GJ but sometimes can be a learning curve to get them on site
So I will just throw out there without seeing the pix,
sounds like the pressure switch has gone bad.

 

[The Cobbler]

pressure switch doesn't really have anything to do with pressure, other than shutting the unit off/on when the set pressures are hit. could be leaking tho.
it sounds like the pump keeps running but wont go beyond 20psi. so it's not electrical.

 

[Jlanman4]

Sorry about that, I thought I had it attached the first time.

 

[Jlanman4]

It runs from the pressure switch that turns the machine on and off, to the L shaped fitting that you can see in the picture.

 

[The Cobbler]

that's the culprit, it's the unloader line . need to replace it . probably 1/4 OD line . copper would work if you can route it in.

 

[Jlanman4]

When I took the housing off, the fan wasn't attached, nor was that unloader line which had a hole in it.

Can I find what I need at a Home Depot or Lowes? And just to be clear, you're suggesting I replace it with a copper line?

 

[The Cobbler]

you might be better off at a smaller hardware store, but you may find what you need @ big box stores. not sure if they sell tube by the foot or not.
I suggested copper as it will tolerate the heat better, but if you're not familiar with bending it, you may want to stick to nylon. but you probably want air brake hose so it withstands heat, regular 1/4" od for water may not be compatible with the high heat it is exposed to. did you remove the nut on that fitting or is it missing too>?

 

[Jlanman4]

I removed the nut. There was also a small metal piece that presumably went on the end of the tubing. It resembles the picture attached.

 

[The Cobbler]

yes the metal pc is called a ferrule / they are used in compression fittings . you will need a new one of those , some tube and probably a new ferrule for the unloader end .
if you don't feel comfortable bending the copper without kinking it , get some plastic air brake hose .
and you need to address the fan too, does it have a set screw or just a press fit/ will it stay on if you slide it on

 

[Jlanman4]

I’ve never bent copper so I’ll probably opt for the air brake hose

The fan is a press fit. I put it back on, but a couple blades did have some minor damage to them. I will post a picture when I get home. Do you think it will work with very minor damage?

Thanks for all the help thus far.

 

[Jlanman4]

You can see the fan damage a little bit in this photo.

 

[jask]

That unloader valve line looks like it burst ... the plastic looks like it got hot and the pressure blew it out. That makes me think it has been well used or even abused to the point of getting really hot for extended periods of use... the fan getting hot enough to fall off the drive shaft and rest on the HOT aluminum rigid line confirms that too. check the pressure release valve and make sure it works, make sure you have a known good pressure valve to read when it builds pressure, and if the P-stat does not cut out where it should you will need to replace it... without knowing what kind of compression it has I would probably put the time and money toward a bigger compressor as these things were really designed to be used with trim finishing guns.

 

[Jlanman4]

I haven’t been able to test the safety release, but it does seem to have its spring loaded pressure. From what little air does build, I’ve been able to release air through both the drainage valve and the safety valve...for what that’s worth.

Does anyone have an idea how to remove the unloader line that’s pictured? I’ve gone to three auto parts stores and none of them have had what I need, but I want to be able to carry that line around to show what I need.

 

[The Cobbler]

HMMM, might be a factory pressed . if you undo the small screws on that plat does that house the unloader valve itself? never seen one that can't be disconnected .
what model of compressor is it?

might just cut the line off where it's good & put a coupling on it if it's a strange connector

 

[Jlanman4]

So I got a new tube and ferrules, the guy at a hose shop showed me how he believed it was connected via a press and release style mechanism. I got home and pulled the old tube out with some force, and while trying to put the new tube in, I ultimately broke the unloader valve off. So, a new one will cost me about $10, I think I’m gonna order a new one, replace it, and see if it works. If not I may just count this as an idiot tax and look to buy a new compressor :/ Thoughts?

It’s a Bostitch, model number says C-pack 300, which appears to be a CAP2000P-OF air compressor, and it included nail guns. I’ve included a picture of a description I found online.

 

[The Cobbler]

if you can get a new one for $10 go for it. probably lots of life left in that compressor

 

[The Cobbler]

unloader valve on ereplacementparts is $4 plus shipping.
https://www.ereplacementparts.com/unloader-valve-p-403875.html

 

[Danglerb]

Replace the fan while you are at it, with that many fins broken off it will be way out of balance as well as not moving half as much air, maybe it was the original failure point?

 

[Jlanman4]

Thanks guys. I’ll give it a go and keep you posted when the parts come in. Thanks again for all he help.

 

[Jlanman4]

This photo makes it seem like there is a screw that should be placed over the fan too

 

[Jlanman4]

*UPDATE*

Ordered a new unloader valve and fan. It was able to build pressure. I don’t know all the correct terminology so bare with me here, but I pulled on the safety release valve and it worked fine, and I also checked the drainage valve at the bottom and it worked well.

My only concern was when I checked the drainage valve, there was some water in there and it was brownish in color. Should I be worried about rust on the inside? I tilted the compressor so I could drain all water out. I’ve also attached a picture of what came out.

Thanks again guys for all of your help and insight.