Restoring Old Compressor

[Pavedog]

Restoring BELL AND GOSSETT Oil-less compressor/Melben Tank

Could really use your guys help as to where to start with this.

This was my wife's grandfathers compressor that he used as a cabinet maker and painter with Bertram Yachts in Miami. It powers up and I have sealed everything that was leaking(tubing, loose connections etc) but it wont build pressure. The motor seems overkill for the tank and is a 240/115V motor wired for 115. The last time it worked was over 15 years ago. Just trying to figure out how to approach this.

Thanks in advance.

 

[Cruzan80]

Won't build pressure means there is a leak somewhere. When it is running, move your hand all around, trying to find where it would come out of. You did check the drain plug on the bottom, right?

 

[CGT80]

The other possibility is that there is a problem with the pump seals, rings, or valves, depending on the type of pump. It appears that may have an oil free pump mounted on each end of the motor. You could disconnect the line/s from the pump and see if you get air directly from the line.

 

[laser3kw]

Not familiar with that brand but have heard of Bell & Gossett.
But, most piston type compressors use a "reed" valve as the one way check valve to allow air in and then allow the air to be moved to the tank. Chances are, if your compressor has these, one is broke. The reed valves are usually attached to the head.
My Craftsman oil-less did that and would not build pressure.

 

[Pavedog]

Restoring BELL AND GOSSETT Oil-less compressor/Melben Tank

Thank you, all good ideas. Will not have time until Thursday to tackle it again.

TO answer one of the questions, yes I went around the compressor and identified several leaks(pin hole on copper lines) and replaced those, plus tightened some of the connections that had leaks.

I could find no pictures of a similar compressor on the web, not sure if they are still in business.

If I pull one of the heads it will expose the reeds?

 

[Pavedog]

Yes, all the petcocks were closed and not leaking

 

[laser3kw]

If I pull one of the heads it will expose the reeds?

If the air inlet goes into the head I would say yes.
you will see two sets of reeds. one allows the air to pass from the inlet into the cylinder then block reverse flow. the other allows air to exit the cylinder but block revers flow from the tank.
If you do find a broken on you will have to track down new oem or you can make them yourself. Or maybe a member here could help.

 

[laser3kw]

here is a picture of my C-man head and valve plate.
The tear drop shape part is the reed. You can see one is broke.

 

[Pavedog]

laser,

Yes, the air goes into the heads, if you look at the pictures the four round cans are air-cleaners with elements inside and they make a 90 degree bend into the head.

The reeds are made of sheet metal and attached to the inside of the head?

 

[laser3kw]

The reeds are made of sheet metal and attached to the inside of the head?

My reeds are attached to a "valve plate" which is sandwiched between the "head" and the cylinder block. That is a common arrangement. You can see the head and the valve plate in one of the pictures ^^^^^^
The reeds are typically made of spring steel. Some of the newer compressors taunt "high grade stainless steel reeds" Don't know if that is "better" or just different.

 

[laser3kw]

Also**
this applies to piston type. If it uses another form of pressure building you may have to do some more investigating.
Just from what I see, there seems to be 4 heads? 2 on each end of the motor - 4 air filters?

 

[Pavedog]

Yep, 4 total. Seems like a bit of overkill for painting, but I bet when it is working it would do a good job!

 

[Pavedog]

I finally got around to taking one of the heads off the pump. The head and the piston sleeve come off in one piece. I do not see any reeds, unless I am missing it(see pics). The piston rings are two parts, in inner spring, and an outer, some sort of bakelite or plastic. The outer looks broken, however if it was one piece I don't know how you would get it on the piston being plastic.

Any ideas?

 

[Larryjones]

There should be a check valve between the pump and the tank to keep air from leaking thru the pump, they can go bad and leak.

 

[Pavedog]

I will check for that. One thing I did have a question on, on the spacer that went between the head and pump there was a spring(on the pink plate above head spacer) that was crushed in the hole next to the screw hole. I could not figure out what the function of that was. Could this be the check valve? There are no outputs on this head I removed.

 

[laser3kw]

you can see in the last two pictures the "reeds". In this case, they are housed in assembly in a check valve fashion. You can see the threads in the port hole. That is the the clue on how to get them out. If you look carefully, you can see a "hex" socket in the center of the reed assembly. I would guess you use a hex key (allen wrench) to remove them. Be advised! Make sure you know which reed assembly one goes in which hole!
You can test them without removing them if you can blow and **** on them. Put your lips up to the hole and blow, then ****. Each one will pass air in one direction and block in the other. The opposing ports in (each head) will act opposite of the other. One will allow you to blow through it and block on ****. The other will allow you to **** air through it and block blow.

 

[Pavedog]

Alright, I think I may be getting closer to resolving this issue. I took apart each of the heads took out the reeds, none looked broken and each only seemed to function one way. I sprayed some liquid wrench into each of the pistons(a little) as it looked rusted. Now it seems to running quieter, and it is building pressure but not enough.

If I block one of the intake reeds with my hand it causes the motor to speed up and seems to build pressure more? Not sure why that is since there are 3 more open intakes. 2 hours after shutting it down there is still pressure in the tank.

Not sure if the issue is the electric motor which seems to be getting very hot too.

 

[Pavedog]

One more thing, if there is a check valve I can't seem to locate it, but I don't really know what I am looking for.

 

[Pavedog]

On further review I did find the check valve and it is stuck open, I assume these are rebuild-able(see pic)?

I have another question, I need to take the motor apart and likely replace the bearing etc. I spent 2 hours trying to figure out how to remove the small fans at the end to get access to the crank and rods for the compressor. Any ideas?

 

[Larryjones]

That looks like the safety valve, it's staked so you won't adjust the settings. If it is bad buy a new one, don't try a repair. Maybe the check valve is built in like others say. It would be between the pump and the tank, maybe even looks like a fitting in the tank. Maybe the ring around the fan hub is what holds the fan on the shaft.

 

[Pavedog]

Larry,

Thanks for the ideas. In this case one of the safety valves would leak air as the compressor was building pressure, I assume this is leading to it not building pressure. Will try and find a replacement.

Yep, you are likely right but I can't figure out how to get the ring off, doesn't look like a lock ring, or snap ring. The end of the hub is knurled, so I thought maybe it would allow you to spin it off but I have been unsuccessful with that too.

 

[The Cobbler]

yes, the part is a pressure release safety. if it is stuck open it's trash. replacements are available but be sure to match the pressure rating and cfm . new ones will likely have a pull ring on them so you can excersize it occasionally by pulling the ring.
looks like the ring on the blade is pressed on, as well as the fan blade . can you pry the ring off using a flat screwdriver ? if it comes off probably the tangs on the blade will loosen enough that it can be pulled off.

 

[Pavedog]

Re: Restoring BELL AND GOSSETT Oil-less compressor/Melben Tank

I was able to pry off the fan, broke it but I should be able to repair it.

As you can see when I open up the compressor there is rubber gasket type material on the inside, I assume this a diaphragm? Most of it is still flexible and not torn, about 2" of it is hard as rock.

I still can not figure out how to get the compressor ends off the electric motor. As you can see in the picture the crank and rods for the pistons connect to the ends of the motor but I don't see a way to separate it. There are 4 bolts that go through the motor and secure the compressor(s) but upon removing those all it will do is rotate but not separate.

Any ideas?

 

[Pavedog]

Restoring Old Gast Bell & Gossett Compressor

I went by an electric motor repair shop today and was told that even though it says it is Bell and Gossett motor and pump it is made by Gast. I have been searching on the internet and contacted the manufacture but can't seem to track down anyone that has parts for this model compressor DTO 315-S.

Any ideas?

 

[Pavedog]

I have been unable to find parts for the motor/pump so I am going to try and find a used or new 1 - 1 1/2 hp motor and pump to swap it out.

Any recommendations?

How do I bend the copper tubing once I have the new pump? Do I need to use anything special on the tube coming out of the pump into the tank due to the heat?