Air bubbles in the oil........

[pescador775]

Check the dip stick to see if the oil is frothy. If not, and oil press is above 50 bar, my feeling is that is OK to run it for a few days. I don't see how the 4th stg could be failing without anyone noticing decline in output, excess blowby or decrease in output press. A bad intake or discharge valve should be causing an OPV to blow or at least cause clicking sounds or similar. However, the increase in oil consumption could cast suspicion on the fourth stage piston regardless.

 

[CraigAClark]

If you increase the oil pressure and notice the fluctuation changes, becomes radical, then I would suspect the piston and sleeve. I'm assuming you know how to adjust the oil pressure.

Has the machine always run at the 4500 PSI shut-off pressure?

The oil pressure regulator has a "seat" which is a ball-bearing captured in a housing. Similar to a bullet crimped into a casing, but with the ability to rotate in the housing. Wear grooves can form on the bearing, which when contacting the sealing surface of the orifice, can actually leak by. This causes a fluctuation in the oil pressure if the "worn" grooves over-lap. Usually shows up as a 200-300 PSI pressure fluctuation.

I'm leaning to the final piston and sleeve as the culprit. Remove the final stage head and use a magnet to pull the piston from the sleeve. If you notice "scortch marks on the piston or it is not concentric and shiney, I would replace it. You will have to remove the upper cylinder to do a "drop" test, but if you see vertical wear (scortch) marks on the piston, you can pretty much consider it bad. If you do remove the upper cylinder, check the guide piston for fractures.

Craig

 

[widget]

If you increase the oil pressure and notice the fluctuation changes, becomes radical, then I would suspect the piston and sleeve. I'm assuming you know how to adjust the oil pressure.

Has the machine always run at the 4500 PSI shut-off pressure?

The oil pressure regulator has a "seat" which is a ball-bearing captured in a housing. Similar to a bullet crimped into a casing, but with the ability to rotate in the housing. Wear grooves can form on the bearing, which when contacting the sealing surface of the orifice, can actually leak by. This causes a fluctuation in the oil pressure if the "worn" grooves over-lap. Usually shows up as a 200-300 PSI pressure fluctuation.

I'm leaning to the final piston and sleeve as the culprit. Remove the final stage head and use a magnet to pull the piston from the sleeve. If you notice "scortch marks on the piston or it is not concentric and shiney, I would replace it. You will have to remove the upper cylinder to do a "drop" test, but if you see vertical wear (scortch) marks on the piston, you can pretty much consider it bad. If you do remove the upper cylinder, check the guide piston for fractures.

Craig

Craig, Pescador - you had it right, increasing oil pressure causes a bigger increase in the oil pressure fluctuation, over 200 PSI movement!!

Gotta be the piston and sleeve.

Took a "stiff whiskey on the rocks" in anticipation of the price shock before calling Bauer to order the parts, - $638.00 (Equivalent in our currancy) for the piston and sleeve,- so I took a few more deep breaths, and thought, while the head is off I will just as well change the final stage valves, another $160.00 - they will deliver friday.!!

They told me for an extra $390.00 (so $390 + $160.00 = $550.00 odd) I can have a complete overhaul kit, (ie) valves for all the cylinders and a few other odds I cant remember - must have been caused by shock.!

Is it worth doing all the cylinders guys, or should I just repair as it fails - of course Bauer claims if one part gos the rest wont be far behind, but they have a vested interest in getting my money.

We have only ever done the final stage valve overhaul, I cant see the piston change been difficult, but is there anything I should look out for, if we go the whole overhaul, is it possible to do ourselves effeciently?

Bauer here dos NO maintainance, they just authorise private workshops in the main cities and as we are very remote, the closest one is about 500 kilometers (300 miles) from us - there is no question I am going to lug the unit there, so its a "do it yourself business" here.

We have the Bauer workshop manuals etc.

 

[pescador775]

Some folks say, "if it ain't broke don't fix it". However, doing replacement engineering at this time makes sense. If it were me I would undertake the work during a slow period if possible. Get the kit with the "few other odds". Otherwise, in a year or two we'll be going through the diagnostic cycle again.

We are lucky to have Craig, an experienced technician, to provide some insights and neither of us are getting any younger. If you prefer someone to "sit in" or audit (from 10,000 miles away) the top cylinder overhaul, sooner, rather than later, would be a good time.

 

[CraigAClark]

Widget, did you actually look at the piston and sleeve? Remember what I said about the oil pressure regulator. Before I would have ordered the parts, I would have looked at the piston and sleeve as well as doing a "drop test" on it. I would hate for you to replace it and find out it is the oil pressure regulator that is the problem. The fact that when you adjusted the oil pressure the fluctuation became that significant, is telling me further investigation (requiring some disassembly) is needed.

Craig

 

[pescador775]

Words to the wise from Craig. Come to think of it, I'm still not hearing confirmation of a fourth stage problem based on performance of the machine, just bubbles and fluctuation. I would get the kit and tuck it away but that's just me. LOL, I tend to squirrel parts and stuff away like with my MIL surplus compressors. In anticipation of the day when NO parts or spares would be available I stocked up on enough of everything to last 50 years. My kids will auction a lot of stuff on EBay someday. No need to go that route with Bauer but stuff will never be cheaper. On the other hand, it requires a long term commitment to a particular brand and model.

Where are you, Namibia? Wait, that can't be right-- strong current and no divers. Are you in or near Mozambique?

 

[widget]

Words to the wise from Craig. Come to think of it, I'm still not hearing confirmation of a fourth stage problem based on performance of the machine, just bubbles and fluctuation. I would get the kit and tuck it away but that's just me. LOL, I tend to squirrel parts and stuff away like with my MIL surplus compressors. In anticipation of the day when NO parts or spares would be available I stocked up on enough of everything to last 50 years. My kids will auction a lot of stuff on EBay someday. No need to go that route with Bauer but stuff will never be cheaper. On the other hand, it requires a long term commitment to a particular brand and model.

Where are you, Namibia? Wait, that can't be right-- strong current and no divers. Are you in or near Mozambique?

Yeah, spot on, about 200 kms up the coast at a small place called XAI-XAI (Pronounced Shai - Shai) we are laying a pipe line and telecommunication cables, about 9 months into a 2 year contract.

I actually live in Johannesburg South Africa, but work two weeks here and two weeks back at the company in Johannesburg, so Yup, no chance in heck of getting the unit to a workshop.
The guys here subscribe to the idea that if it cant be fixed with some barbed wire, spit and a lot of hope - we dont want it. - just kidding, but it has its challenges out here for sure.

Well, the parts are a-coming - soooo, ............!!.

Craig, good point, I am stopping the unit and I will check the piston tomorrow, I think output is down though (although its difficult to judge as the two units work in tandem) and there appears to be excessive oil in the discharge.

Will heat have a lot to do with it ?, its around 40 degrees centigrade out here with no breeze, the compressor room has exhaust fans but inside it gets super hot.

I would really be most appreciative of assistance from 10,000 miles away Pescador and Craig, I dont profess to be anywhere near as knowledgeable on compressors as you guys, and here its a case of sort it out yourself.

 

[pescador775]

At that temp, it is a good thing that the compressors are four stage. Heated cylinders and oil can affect air purity. Just maintain them regularly and so long as there is air flow throught the fan things should be OK. With the DIY filter I assume that hopcalite is not being used. That is a catalyst for carbon monoxide which is normally included in a triplex cartridge. The Corena 150, a 40 weight synthetic oil, is the right juice for the machines. It has been shown that under certain conditions, break down of oil can produce toxic gas which is adsorbed by the charcoal. If the charcoal breaks down the bad stuff can be tasted by the diver. However, rarely, without catalyst, the CO can be "cleaned" but not detoxified by the filter and could present a silent threat. There have been documented cases, the most recent in the Maldives, or one of those other Indian Ocean Islands. Also, believe it or not, there was a case in Canada (fire dept) and in Georgia, USA.

 

[widget]

Yes, I have dived recreationally on some of those Indian Ocean Islands,- atrocious maintainance of everything is the norm.!!

I am not even sure its due to lack of cash, as these little islands bustle with tourists from Europe, I think its a lot to do with lack of experienced and capable people, not to mention its just such a logistical, expensive and buerocratical nightmare to get anything into and out of the Island.

........but yes, I read about the Maldives issue, - but I have to say it sounded like a severe lack of maintainance there - theres no excuse for that.

..............anyway, off to go start stripping the machine - already 35 degrees and its only 7.30 am.!!

Let you know later.

 

[windyairman]

a quick easy way to check your final piston is
Remove final cylinder head
clean top of piston with a rag.
then run compressor with head removed.
if you can see oil leaking past the piston / liner
then its worn out.
other posts on this forum,oil reg valve/ suction&delivery valves etc are also correct.
its a quick easy field test that can be done to save strip down time & a lot of -about