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

[widget]

Yes, sure it makes sense Pescador, I think I tended to look at the ball and it looked fine to a quick glance, when you and craig spoke about gouges, I sort of expected to see very visible marks, but I didnt, so I thought it was fine, but it appears under a glass the gouges are quite visible (okay probably a younger fella than me with better eyes would have seen them easier) but I have learnt now to look at everything very carefuly.

What do you think on the ball, can I use anything that size to test do you think.?

Although if the ball is damaged the orifice on the sealing disc is probably shot as well, so its not going to be a guaranteed result I guess.

 

[pescador775]

Widget, I feel that a substitute ball bearing of the correct size should work.

 

[CraigAClark]

Hey Pesky, it actually acts as a relief valve. The oil is pumped directly into the regulator and final piston. Once the set pressure (spring set)is over come the "poppet" (ball and carriage) separate, allowing oil to be vented back to the crank case. So the valve does not interrupt flow from the pump to the piston.


Craig

 

[pescador775]

Thanks, Craig. I slapped my head and deleted the post before I read yours.

Edit: Some aspects to this are making me a little miffed, move over Widget while I take a wrench to that thing, LOL.

It appears to me that as long as the regulator plenum stays full of pressurized oil that bubbles cannot intrude. If pressurized oil from the pump is leaking through the regulator valve and out the bypass it would seem that the plenum would not stay fully pressurized, not retain the designed volume and pressure of liquid when the pump is on the downstroke, and that some of this space could be filled by a gas bubble of higher pressure with some of the gas in solution. Oil is not compressible and a great deal of leakage would not be required to drop the oil pressure and allow intrusion of gas. Since the intruding gas would quickly assume equal pressure the oil pressure gauge would not always show a discrespancy. However, a gas does not act like a liquid being highly compressible and a bubble can pass through an orifice or leaky valve at a rapidly variable flow rate (sputtering). Once the micro bubbles passed through the valve and into the sight glass their volume would increase by a factor of 50 (50 bar/1bar). The build up and release of gas could cause significant fluctuations in gauge pressure and would be more noticeable as regulator pressure setting is increased. IMHO

 

[CraigAClark]

Pesky, would it not be possible that the space occupied by the gas, colapse once the liquid was introduced to the plenum. Thus being a repetative cycle of gas, replaced by liquid ending with the "Farting" of gas into the liquid resulting in the fluctuation of the liquid pressure?

Craig

 

[pescador775]

Yes, I think so but this is happening at 1200 rpm and so the fluctuations might not be noticed by the gauge. However, there might occur an overlapping of pressure cycles which could result in a kind of mathematical resonance causing a slower cycle laid over the more rapid cycles. The storage chamber (plenum) is small and subject to pulses from the cam driven pump and the 4th stg cylinder. IMO, either that regulator works near perfectly or some nasty variables are introduced into the mix because the regulated hydraulic pressure cannot abide intrusion of air (think brake lines). Flow from the pump would tend to drive oil and small bubbles fore and aft, either washing into the cylinder or into the return line. As you say, temporary voids filled with gas could result in pressure variations because of the compressibility and evacuation of the gas followed by flooding with oil. That might be assumed to be the most detrimental to the compressor. The theory and discussion is an attempt to explain observed conditions that you and others reported. I guess I can't let something go until it is understood or explained.

Pesky, would it not be possible that the space occupied by the gas, colapse once the liquid was introduced to the plenum. Thus being a repetative cycle of gas, replaced by liquid ending with the "Farting" of gas into the liquid resulting in the fluctuation of the liquid pressure?

Craig

 

[widget]

Pescador, you kinda lost me there, but believe me that socket wrench is yours .

Forgive me, but reading your post, are you thinking maybe the issue could be in the pump?

I gave up trying to find an 8mm ball bearing today, so I just went along to Bauer and picked up a kit 072439 it was relatively cheap at 40 bucks so I wasnt going to argue. I am flying back tomorrow afternoon, it will onlt take a few minutes to install the kit and I should know.

Do I need to think of an oil pump kit as well guys, I can pick one up tomrrow morning I guess if needed.

 

[CraigAClark]

Widget, in 20 years, I have never seen an oil pump fail, but I guess anything is possible. I don't think you can get parts for the oil pump, at least not from Bauer. None of my books show an exploded view of the pump. Personally, I think the regulator is the culprit. Someone suggested swapping regulators with your other machine. that would end the mystery for sure.

Craig

 

[widget]

Yes, I remember, well I have a new kit for the regulator,(aahh the pleasures of been in a city again where you can just drive 10 miles down the road and get what you need) - so it will rule that out if it dosnt work.

But, I think you are right, it has to be the regulator.When I get that little ball in my hand I will take a pic and post it here, would you have a look and let me know what you think Craig??

 

[pescador775]

Widget, I was not implying anything about the pump. We had a guy here who had to replace a broken cam bolt but I have never heard of a bad pump. The cam (eccentric) drives the pump and is fastened to the crank with a bolt. Hope the repaired regulator eliminates the problem. It should.