Trane recip oil pressure

[dgruber]

Anyone out there have some oil pressure information they can share.
Trane "R" Compressor M/N CRHR500A4HAO

Been a awhile since I have opened one of these compressors, and my compressor rebuild re manufacturer friend has moved, so I cannot pick his brain, until I locate him.

I think the oil pressure needs to be around 35 to 40 PSIG Net to operate the unloaders correctly or are the unloaders not dependent of the oil pressure to operate correctly.

Running fully unloaded the oil pressure becomes very erratic and causes a oil failure safety trip. No foam in the oil sight glass and about half a glass. Oil pressure is running mostly around 30 to 35 PSIG Net. Oil safety Cut Out is 15 PSIG and Cut In 23 PSIG

I will change the oil and liquid line shell driers, along with removing the compressor hand hole cover for inspection. Looking for anything out of the ordinary.

This compressor pumps down to zero and holds for about 10 minutes.

Going back with the Trane oil, only because I seem to remember O Rings may swell with any other 3GS being used. Used to have to use Capella D in Trane Recips, but that was in the 80's.

Anyone out there that has any knowledge of this compressor, please share idea's.

[maxster]

i show the R compressor with electric unloaders with no oil dependencythose should be powered (magnatized)unloaded on a start from the controller,and the oil saftey mounts on the terminal box and caps out to the suction and oil pump.forget the hand holde cover..sound like your OLP your pressure is there off the pump and its tripping....are you flooding back any on the bottom of the suction into the compressor middle one or the left one is you compressor http://images.google.com/imgres?imgurl=http://www.advancedhermetics.com/images/trane_Image.jpg&imgrefurl=http://www.advancedhermetics.com/trane.html&h=325&w=500&sz=101&hl=en&start=3&tbnid=jKgqX0KsP-favM:&tbnh=85&tbnw=130&prev=/images%3Fq%3Dtrane%2BR%2Bcompressor%26gbv%3D2%26sv num%3D10%26hl%3Den%26sa%3DG

[whec720]

What is your suction pressure OP when running unloaded? This a R-22 chiller?

[freonrick]

30-35 psi is good for the "R" series compressor. As already stated the oil has nothing to do with the unloaders. I would not pump it down to 0psi. I would rather have it a 25-30 psi. This is only my opinion. I never had any problem with 3gs oil and the orings in them. I have some that the customer has me do a top end on every year and I use 3gs oil. The only weak area would be the suction valve springs. Its best to replace them before they start breaking.
If you pull the hand hole cover just do a good visual inspection. If you pull the oil pick up screen replace the o ring for it. that can be a job in it self so dont pull it if you dont need to. They may be some small magnets in the sump that you can pull out and clean while your in there.

[jayguy]

Oil pressure is running mostly around 30 to 35 PSIG Net. Oil safety Cut Out is 15 PSIG and Cut In 23 PSIG

typical oil pressures are 23-32 psiD. your cutout numbers are correct. i would suspect the oil pressure safety switch. i am not fond of those capillary switches...junk! i have modified some J/C switches with superhoses and it worked well. the unloaders are electric only...not oil dependant.

30-35 psid sounds great...change out the switch first IMHO.

good luck.

[dgruber]

Maxster,

These are pics of the the good operating compressor #1.

The other compressor #2 ,on this system is shutting down.

We are doing a annual inspection and wish to document pressures and temperatures along with pictures. We like to look inside, check magnets, oil screens and wipe out the sump. We like to check the liquid shell cores for any metal or dirty.

Compressor # 2 was turned off and disabled until troubleshooting during winter could be performed. Crankcase heaters are working fine and compressors are located in a hot boiler room inside the building.

Yes starts unloaded by de energizing the unloader solenoid coil. The oil pressure will flutter the gauge during full unloaded, which is the point of safety shutdown. Kind of like hot gas discharge pressure off the compressor will do to your gauges, unless you crack the service valve ever so slight.

I will monitor superheat during this condition. The oil does not become foamy and the suction temperature feels good to touch, on the compressor body.

Thanks for the feedback and please post your thoughts should more come to mind.

[dgruber]

Thought I had uploaded Ok, but I must of lost them in the final posting.

[dgruber]

Jayguy and freonrick,

Thanks for the feedback. I will consider changing out the differential capillary oil pressure switch.

I am still not sure why the oil pressure flutters the gauge, though, just before shutdown? maybe the fixed gauge is weak. They remain shut off except when servicing, but still I may cross check with a known good gauge.

Good to hear the oil pressure sounds strong. I only pumped down to 0 psig, only to change drier cores and remove hand hole covers. Also to check the suction valves.

Thanks!

[jemawalton]

I don't think Trane sells the the capillary switch for oil pressure anymore. Last one I changed they gave me a retrofit kit (sort of) that had a standard dp switch.

[garretak]

I don't think Trane sells the the capillary switch for oil pressure anymore. Last one I changed they gave me a retrofit kit (sort of) that had a standard dp switch.

That's true, they sold me the "retrofit kit" too. A ranco switch I believe with the price doubled because the box said trane!

[jemawalton]

The last one I did, the pressure ports were labeled incorrectly causing about an hour of sheer confusion on my part. That's the last time I install an pressure switch without testing with N2 first.

[maxster]

set your self up with a liquid filled suction guage with a quick clip/connect ON gizmo..no hose ....no oil bath on the way out.the guage bouncing is the actual pump your seeing try ctanking down the service valve for the oil guage to steady it up.

[stickerhead]

Got to remember, the oil pressure switch is tied into the MP-23 Black box. It has an internal bleed port inside the switch. Some Model R would break or bend the pin in the oil pump. I have changed the oil pump assemblies and they work fine. But, there is a certain way to install the pump. If that doesn't work, the front or rear main is probably worn. The oil type you refered to is on Trane Model E's. Some oils would cause the unloader o-rings to swell. These compressors are hydralic unloading, R's are electric as stated above.

[ga1279]

Typically your Robertshaw Guard pak give you 90 seconds to build solid oil pressure as sensed by the oil pressure differential control (CNT-0553) if your oil press is erractic after that time period it becomes additive to a 30 second count. If you don't show any violent activity in the sight glass I would look at two things, the oil pick-up in the sump and the oil pump itself. If the bearings were going bad your oil pressure would be constantly low, same with con-rod journals. Typical oil pressure for an "R" is 30-38#s net. The controller you have is acting within spec's cut in 20#s cut out 15#s
ga1279

[dgruber]

Opened the hand hole cover and found everything together. Rods,pistons ect.

Two bearings have some excessive play. I believe the rod bearings are worn through to the aluminum on one or two rods. Hard to tell at this point without removing the caps.

Found some ground aluminum in the sump.

We cleaned the sump out and changed the oil and liquid driers. Started and monitored. Oil pressure surprisingly good for what we found and stayed online, although we have shut this one down to only be used in emergency, until the replacement compressor is approved.

Thank you all for your replies and sharing your experience. It would b nice to do a autopsy on this compressor, once changed out. Like to know a little more about the system.

Is there excessive flooding back of liquid or head pressurers to high during heavy summer loads? Valves are tight as we can pump down to 0 psig and hold.

[dgruber]

A few more for the interested folks.

Thanks again and please post if more comes to mind.

We are all on a learning and exploring curve!

[TRGunner]

Opened the hand hole cover and found everything together. Rods,pistons ect.

Two bearings have some excessive play. I believe the rod bearings are worn through to the aluminum on one or two rods. Hard to tell at this point without removing the caps.

Found some ground aluminum in the sump.

We cleaned the sump out and changed the oil and liquid driers. Started and monitored. Oil pressure surprisingly good for what we found and stayed online, although we have shut this one down to only be used in emergency, until the replacement compressor is approved.

Thank you all for your replies and sharing your experience. It would b nice to do a autopsy on this compressor, once changed out. Like to know a little more about the system.

Is there excessive flooding back of liquid or head pressurers to high during heavy summer loads? Valves are tight as we can pump down to 0 psig and hold.
Ga 1279 is right on the money. I would also look out for Liquid flooding back from a malfunctioning TXV causing it to wash out your oil.

[fac 213]

Dgruber

I have service literature and overhaul for Trane Semi Hermetic Compressors
Model E. It might help you out if you plan to to do a overhaul. Send me a fax number, and I will send you the info. My e-mail is in my profile.

[dgruber]

ga1279,

We noticed the pickup in the sump was loose at a connection of the tube, part way between the sump screen and he inlet to the pump.

This may have been pulling in refrigerant suction vapor in the crankcase along with oil pickup?

What do you think?

[jayguy]

"aluminum" in the sump is bad news. you need to remove the rod caps and bearings now and inspect. if there is any gouging (it does not require much) on the crank, then you are money ahead to purchase a new compressor. the cranks are very expensive and by the time you add labor to change out all of the affected rods, bearings, etc. you would have a new compressor installed cheaper and you get a warranty.

if the crank shaft is ok or there is extremely light scuffing, then you will probably be ok...but i would recommend a complete overhaul just to make sure that all is ok.

but then where did the aluminum come from? old compressor? i doubt it.

no matter what...rebuild or replacement...find out what is going on (usually liquid...running or at start up for crank shaft wear).

good luck.

[tunaguy]

Oil color looks dark to me. Aluminum oxide will turn oil black. That is a lot of fine aluminum in the compressor. Main bearing wear will lower oil pressure, sometimes oil pressure will change depending upon the load, whether it's a R, E or F, due to worn journals.
One test you can do without teardown is to reverse compressor rotation. Oil pump is not rotation sensitive. Oil pressure should not change much if main bearings are good. Should main bearings be worn then oil pressure will change, may even increase hopefully. Sometimes you can buy some time in the middle of a hot spell by doing this. However, I have also had compressors seize because journals are so worn.
Another test is to rotate compressor with heads off until a piston is on the down stroke, stop rotating then push hard on top of piston with a tool. There shouldn't be any "play". Test one piston at a time. Slop indicates main journal wear.
If crank is worn then the compressor is toast. Good luck!

[ga1279]

dgruber,
Yes that is a path for refrigerant to enter the oil system, but that would mostly be vapor from the crankcase. One other point if your looking to replace connecting rod bearings good luck. The surface of the connecting rod that the crankshaft rides in is a machined surface in the (aluminum) there is no bearing there. This is were all your aluminum particulate is coming from. There are two actual bearings and the crankshaft rides on them. One between the motor and compressor and the other is behind the oil pump. The rods that have the play are closer to the motor side or the oil pump side ? This would mean liquid returning to the sump, the bearing in the center would also suffer causing a condition called rotor drop. The rotor would eventually drop onto the stator.
Hope this helps
ga1279

[dgruber]

ga1279,

The path for suction vapor to enter the oil system must have been why we saw the oil pressure gauge flutter, during operation?

The motor side and oil pump side outer bearings, both, seemed to have the excessive play.

We have ordered a re manufactured compressor, which we will install in the next few weeks.

We will have to monitor the superheat and possibly adjust the TXV. We may ask the re man shop to provide a tear down report, of the returned defective compressor, so we can have some additional system diagnosis.

Thank you all for your participation this thread!

[jayguy]

We may ask the re man shop to provide a tear down report, of the returned defective compressor, so we can have some additional system diagnosis.

a fantastic idea! i can not usually get my customers to pay for one or let me do it. it makes the process of figuring out what went wrong take much longer...and even then you never know for sure what took out the old one.

good luck.