Halls V92

[aupanner]

I am having problems with a Halls v92-4 (mk2) LT. The oil drops in the crankcase and returns as soon as the machine trips on oil failure. I have fitted new lip seals to the cylinders and replaced the o ring in the housing that holds the shaft seal.I did pump oil to the cylinders to check the liner seals after and they seem ok as the unloading pins stay down The problem is still there and I am sure the oil is moving into chamber at shaft seal end of compresser as it returns as soon as the compresser trips. Is there any thing else that would cause this problem?

[Grizzly]

Which loading gear seals did you fit?
Milflex or dowty style?
When the comp is ran do you see a diffence between the suction and discharge pressures?
Grizzly

[Magoo]

With the disappearing oil level, is the sightglass foaming. Could be due to over saturated suction vapour or oil temp too cold. When compressor stops the sump pressure inceases and oil settles out and level returns.

[Grizzly]

Hi aupanner.
Just to add, when you overhauled this machine did you check the oil strainer and oil filter?
Just trying to understand what operating conditions you have.
As Magoo indicates gas logging preventing the oil pump from priming is the most logical.
May I add that I once was in involved in a MK2 which had been looked at by many experienced Halls Engineers myself included.
Before the answer was stumbled upon, in that instance a new set of Liner seals were found to be the older Dowty design P/No 38412-237-2 (Int.) 38412-236-2 (Ext.)
Halls will supply what is ordered.
In this case the seals came Via Star and if your accompanying manual is old enough these will be listed.

Hopefully the above will allow you to confirm what you have at least?
Grizzly

[aupanner]

Hi Thanks for the replies. The oil filter was replaced and strainer was cleaned. The compresser is part of a two pack system on a Low pressure reicever system running a cold store. The other compresser runs ok so I am sure the oil is not getting saturated with refrigerant. The crankcase heater is working. The cylinder seals were replaced with the same type as removed. Long before I started looking after this plant this compresser has had this problem.The oil drops in the crankcase but I think its still in the compresser some where as when it trips the oil returns quickly. The solenoid from the oil seperator is closed when the compresser is tripped so this also make me sure the oil is still in the compresser.

[Grizzly]

Ok so most of the discussed discounted.
How long from initial startup does this comp run for, before tripping on Oil Diff?
Grizzly

[monkey spanners]

Just a thought, is the oil seperator solenoid a normally open or normally closed type?

[aupanner]

The solenoid is a normally closed type and the compresser trips off in less than 1 hour.

[Magoo]

Would tend to point to the oil separator, a restriction in orifice. From memory the J&E Hall oil separators had a range of orifices fitted. For different oils and operating conditions/ temps etc.,Could be the long term problem explanation.

[Grizzly]

Hi Aupanner, back again!
You seem to have covered all the bases so far, when you did the overhaul.
Were the piston rings changed or checked?
As the oil as you originally state must be going somewhere.
Most of us reading this remotely (I think?) are considering a oil return issue.
Have you checked the operation of the oil return solenoid valve? Could it be passing?

However if this is the case that there is indeed an oil return issue then the oil is being Pumped out of the compressor?
Historic issue is always difficult to remedy especially as you seem to be doing everything "By the book".
Personally I still think there are issues with the compressor.
Whilst it is running can you see the pressures and amps change as it loads up?

Normally a fading oil pressure is down to internal issues usually based upon a poor service regime.
Add your disappearing oil level and it's slightly confusing.
Sorry I cannot be more specific but you as the site Engineer have a better grasp of what is happening than us guys remotely.

The V92 hold anything between 9 and 18lts of oil dependent upon size. Thats one hell of a oil pump your comp has become.
Grizzly

PS Humour me if you will and check those seal part numbers please.

[aupanner]

Thanks for the feed back. when the compresser trips the oil cannot come back from the oil seperator so thats what makes me think the oil is still in the compresser and in the front housing beside the shaft end. There is a tube from here back to crankcase and it is clear. I think basically I am wanting some one to say it has to be the lip seals on the liners.

[Grizzly]

Well that is what I am trying to say!
Or at least a Contender.
I am working away all next week so if at the end of the week you have not confirmed which type you are using.
I will dig out some profile drawings.
Grizzly

[Magoo]

Hi aupanner.
from memory the liners are open to the dry suction vapour gallery internally. That gallery has a drain plug type orifice back to the sump. If a lip seal was dumping oil into that gallery it would take a while to drain to sump. So you may be correct in saying that a lip seal/ s are leaking/passing. Normally the oil in loader is dumped to sump by the solenoid loader block.

[aupanner]

Finally found problem. I found it by luck and loads of people have looked at this compresser for this problem. The compresser was remanufactured years ago and there is a pipe from the front housing to return the oil to the crankcase. The pipe goes trough the casting and then turns 90 degrees up hill in the crankcase and stops about the same level as the top of the sight glass. I think it is like this so if the piston rings are passing the oil will not be forced out of the crankcase. Well the remanufacturers must have lost or damaged this pipe and made up a replacment,the pipe was not a tight seal going through the casting. I had emptied the crankcase of oil and had the front cover of and noticed oil passing pasted the outside of the tube. I removed the tube and refitted it with a sealant and the problem is now gone.

[Grizzly]

Brilliant and well done.
It is always nice to resolve an issue and thanks for bothering to reply with the answer.
Grizzly

[Magoo]

Do not understand the resolve of problem.