Bauer Utilus low interstate pressures

[wwunder]

Since you started this thread, my compressor was running really hot on the second stage so I dug in and replaced the 2nd and 3rd stage valves. Now it runs cool, but my second stage is only producing 300 to 400 PSI. The first stage is still up with 50 to 60 PSI range. The biggest problem is that the compressor is quite noisy and I'm thinking that the pressure isn't enough to keep the floating piston in contact with the drive piston.

I'm thinking that its got to either be second stage rings or the third stage piston/ liner, but any guidance would be appreciated.

 

[sealark]

I hope you have a tank hooked up when testing and the drains closed because that compressor needs back pressure to stop the knocking of the floating third stage. If it knocks while charging and pressure is building in tank you got other problems.

 

[CraigAClark]

If the unit has a PMV, why do you need to hook up a tank? If it doesn't have a PMV the filtering process might be a problem.

 

[sealark]

Yes a PMV will also allow a buildup. If the drains are closed. A tank hooked up would give you a little time while running to look for a problem.

 

[wwunder]

Ok, a few more details... I have two of the same block a k13 and a utilus u-1. The U-1 is set up with an interstage separartor, final separator, little filter with the OPV then a check valve, 16" mako tower and PMV. The compressor will pump all the way to the OPV (3200 psi) without issue other than the noise. The second stage was overheating so I dug into the valves and ended up replacing all of the second stage and third stage valves. Once the valves were replaced, the second stage pressure dropped from about 550 PSI to less than 300 PSI. The knocking is slightly quieter than the startup, but is still quiet noticeable. If i open the second stage separator, it quiets all the way down. I'm assuming this is due to the floating piston staying at the top of travel. I pulled the second stage cylinder last night and found the top piston ring jammed in the ring groove. I'm thinking a new set of rings on the second stage is in order. If i need to trouble shoot the third stage, i could swap the k13 3rd stage cylinder, sleeve, piston onto the U-1.

By contrast the k13 is currently only knocking for the first few seconds and then settling in and running quietly. It has its own second stage overheating issue as well, but I don't have insterstage pressure gauges on it to check yet.

 

[CraigAClark]

A new set of rings will only help is the cylinder wear is not out of tolerance. Unlike other types of cylinders they can't be resleeved (at a reasonable price) nor can you buy oversized rings.

 

[wwunder]

Thanks craig... I'll try swapping some parts back and forth from my other block. Would you recommend using feeler gauges in the ring gap or I have some telescoping bore gauges to check the cylinder wear? The walls aren't scored or anything.

 

[CraigAClark]

Hone the cylinder, place a new ring about an inch down and use a feeler gauge. Sorry, but I can't remember the max allowed gap.

 

[wwunder]

Haha, thanks so much... problem solved today. While I was farting around trying to check things I spun the flywheel by hand and detected a very slight deflection. The darn tightening bolt had worked loose and was obviously causing the knocking. She is now running nice and smooth and quiet.

Now I need to get some gauges onto the k13 and figure out why it is running hot.

 

[Scuba_Aaron]

I know this thread is a little old but I was curious on how you go about measuring interstage pressure? I did some googling but haven't found what I am looking for.
I have a Bauer Utilus that isn't building up high pressure, the 3rd stage valves are probably the problem here and I want to double check that the 1st and 2nd stages are ok.