Bauer Capitano will not retain oil in sight glass after shutdown

[scratchandskiff]

I picked up a used Bauer Capitano recently which was running fine. I changed the oil in the compressor and bled the air out of the system as directed in the owner’s manual. I filled a couple tanks and when I shut the compressor down I heard a metallic click sound after about 10 seconds and noticed the oil draining from the oil sight glass, and audible gurgling sound, and smoke (I believe to be atomized oil) from the intake tube.

After this, I bled the oil line of air and ran the compressor again and the same thing happened on shutdown but this time I unhooked the oil pressure line from the oil pump and air was coming out of the line (backflowing) towards the oil pump.

Before I changed the oil the sight glass held oil in the window and now as mentioned earlier after about 10 seconds it fills with air. When the compressor is running everything appears to work perfectly.

I suspect it may be what appears to be a inline check valve but I am pretty new to scuba compressors so hopefully someone can point me in the right direction.

Thank you!


The link below is a couple videos of what I mention above...

https://1drv.ms/f/s!AmloHgmFevsokW5br1qPaMK4i537

 

[iain/hsm]

The problem with your compressor is not quite how you describe it, but the good news is it is reparable. Your best solution is to find a local Bauer service repair centre in your area and have them repair the compressor for you.

 

[scratchandskiff]

The service technician said what I am experiencing was normal. I will post what he told me to help others who may experience this....

There are no check valves in the oil lines.

As the third stage floating piston wears, there will be blowby leaking past the final piston and pressuring the crank case which then air pressure can evacuate the oil line on shutdown.

He said atomized oil/ (evaporative water) vapor is part of the normal lubrication process for the 1st and 2nd stages and it was ok to have a little ‘smoke vapor’ out the intake on shutdown. (Especially when the compressor is hot and water evaporating out of the oil was a good thing)

He said to consider a rebuild if the air output starts dropping off. Right now I am getting more than the listed factory specs so unless I hear otherwise I will keep driving on.

 

[iain/hsm]

What he said would be useful, as there is insufficient knowledge to know whats wrong from your description.
Correct, The (check valve) you describe is probably a "wire wool" type filter. It looks like a 1/2" crimped bulge in the 1/4" oil line tubing.
I doubt you have piston wear, or blow-by, unless the pump is very old or worn out but this can be easily measured by the service folk or yourself if you have a flowmeter and a small hose to connect to the crankcase where the oil breather is located.
Atomized oil is OK and needed, replacing a busted or removed air intake filter will stop that steam
Surprised he didn't measure the oil pressure for you.

Instructions for measuring blow by enclosed below
Oil pressure can be found in manual
Threads are metric (not imperial) for connections

Bauer Blow-by Test.pdf - ScubaBoard

 

[iain/hsm]

We should write a self help service check list one day
But you stated you changed the oil in your post
You didn't change from mineral oil to synthetic?
These synthetic diesters can lift any carbon deposits from the original mineral based oils left behind
and cause havoc with the filters and interstage valve seats with the bits of carbon deposit breaking off
blocking up the valve plates open

Also check interstage pressures all stages is my first check.
Oil pressure second check
Charging rate next
Blow by is a check done much later or on old clunkers
A dead head test is also a cheap and useful test by charging up to pressure then switch off and see
if any of the interstage gauges creep up (valve leakage) or if no gauges fitted a cruder way is if a relief valve "pops" due to a build up of overpressure in a lower stage. Not as accurate a pressure test and a bit crude.
RPM check of the flywheel and a clamp meter over one of the phases is also useful to see if the Kw power needed is not exceeding the motor rating and a warning of something about to seize up before it does is also useful.

That said and I can't see your video post so it doesn't really matter what I say.
But your problem is probably going to be with your oil pressure or oil pressure setting regulator

 

[scratchandskiff]

Thank you sir very helpful information and makes sense.

I changed oil with synthetic oil chem lube 751 and the previous owner said he was running synthetic (chem lube 800).

Rpm is good (3600- With new electric motor) . Air output is about 5.3 Cfm

I don’t fully understand why but I think based on about 4 knowledgeable people telling me to check my oil pressure, I am thinking some of this is imy oil pressure reg

Getting a oil pressure gauge from August industries now as we speak.

 

[scratchandskiff]

Funny. I was researching Bauer compressor discussions and came across this. Read it and thought I need to reach out to that guy cause I had the exact same thing happen years ago... Then realized it was my original post from six years ago. I am happy to report after 6 years of use, there has absolutely been no issues with the compressor whatsoever and it continues to fill at the factory rated output. The problem above was that I did not dump the condensate drains on shutdown. Shortly after this post I started doing that and it "fixed the above issue". If ever I don't drain the condensates the backpressure will cause the oil to atomize as described. Posting this to help anyone else who may be experiencing it

 

[happy-diver]

I need to reach out to that guy

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