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For these two compressors, we only picked up the one with better condition to repair, we have order new bearing kit, gasket kit, shaft seal, eye seal ring and B.P seal ring for replacement,
We also sent the impeller locked with high speed shaft to a factory for dynamic balance emendation, what they do, they put the impeller with H.S shaft on a test machine(Schenck, made in Germany), accelerate to at most 1800RPM, and they adopt weight-removing method to achieve acceptable balance,
This is somewhat controversial to me, firstly the speed for test is far less than the real speed, I doubt the result won’t be able to reflect real condition, secondly, when every time they grind away some weight from my impeller, I am a little fearful, I am afraid that too much weight could be taken off,
Just wonder what you do the balance for impeller in USA,
The compressor has been assembled already, I haven’t thought of the roundness of the shafts as their surface looked smooth, if it is imperative, then I think it is better for me to disassemble the compressor for further roundness examination.

Gentlemen, thanks for your advice, I do have learned a lot from you.

Attachment 315581 Here is a York OT with aluminum bearings apoximatly 30 years old, that has never been overhauled! It was a R11 machine, shells rusted out and tubes had to replaced so we put her out to pasture. She was got a lot of TLC and they got their moneys worth out of her! Bearings? Oil is the bearings, keep it clean, right temp, right pressure who knows high long this one would have run!

Taicool - What you are basically looking at is the finesse part of our job. You examine all the bearings for wear indications, metal scraping (wiping), overheated spots on rubbing surfaces. If the machine hasn't run for 7 years you have other problems. The low-speed and high-speed shaft have not been rotated and the weight of the shafts may have settled into the lower portion of the bearing causing it to become an oval and out of round. Depending on the shaft size, you need an outside micrometer to measure the actual shaft diameter, at least 3 sets of readings on each surface the bearing rides on. You are verifying the shaft is 100% round and within tolerance. Next use a set of inside micrometers to measure the inside diameter of the bore of the bearings. In this case the more readings you take the better, just make sure all readings are taken at the same depth as previous readings (ie-1" inside on both sides) 360 degrees and the micrometer stem is perpendicular to the bearing surface. I would also advise an oversized clean up kit as you can't clean the rust from the inside surface of the evaporator or condenser. Good luck and if by chance I'm talking over your head with these directions get a chiller technicians who's been down this street before. No disrespect intended toward you. It just a lot of money involved with this work. -GEO

Use Dow-Corning High Vacuum Grease.

As to the PRV control shaft lubrication issue,
the lubricant used is described as Beacon Grease and Molykote with P/N 360-00125 in the service manual as attached,
because I did not order the lubricant from York,
I consulted with the engineer of Molykote dealer in my city, and he suggested me to use Dow Corning 111,
can anybody advise if it is feasible?
Thanks in advance.

Originally Posted by Taicool

I have no way to access the professional forum because I don't have any american official certificates
Tung

Being from the USA or having certs from it is not a requirement to be a Pro member. Apply and the membership committee will see if they can verify that you are in the HVAC trade.

Mic stands for measure with a micrometer, but if you don't know what the measurements then that endeavor is useless.

Spec stands for the "specification"...in other words, the exact dimensions of the bearing and it's tolerances.

Originally Posted by Taicool

although I have no way to access the professional forum because I don't have any american official certificates

I don't know that you need any American certificates to apply for Pro status. If you list your qualifications, how long you've been in the trade, who you've worked for and other details about your professional background you should be considered for pro status. I had the impression you may have worked for York or Johnson Controls at one time.

Ok, there were some mistakes here,
I have no idea of what the abbreviations mic and specs stand for,
I thought them as some kind of test that has to be carried out by professional people with special instruments,
although I have no way to access the professional forum because I don't have any american official certificates,
as to the manual 160.45 M1.1, yes I do have a pdf copy,
thanks a lot for the advice, that is felpful.

Tung

I think a chiller tech needs to be involved hands on so they can see the whole thing. something can be misinterpreted when we cant see what you have as a whole. too much money involved for a mistake.

Agreed. I should have never said those things. MODERATOR: Can you delete my post #9? Taicool, you need to apply for Pro Status. Technical discussions need to happen there, not out here in public.

This is getting way too detailed for an open forum.

Originally Posted by freonrick

clean them up and mic them and see if they are in specs.

Sir,
could you provide the detailed information of the test for aluminum bearings?
thanks in advance.

Tung

Gentlemen,
Thanks for your reply,
I apologize for my short of knowledge of Aluminum material,
can anybody here kindly inform me more about the spectrum?
what is the test and what fact can it clarify?
actually I have suggested my customer to replace all the bearings as none of us dare to take risk of possible failure,
because the price of two sets of bearings is as high as about $65,000,
and my customer don't have any extra budget for the expense this account year,
so they incline to reuse those bearings if they are still usable or can last for at least six months,
when I opened these two compressors, they looked terrible,
rust and dirt are everywhere inside the machine,
it has took me one week to clean them and the job is still ongoing now,
if the spectrum can clarufy the condition of bearings, then I would think of doing it first.
again, thanks for your opinions to this matter.

1. I think as stated earlier what are the spec readings ?
2. Is the customer ok with using these parts if so failure could happen sooner than later ?
3. If it was your machine what would you do ?
4. Aluminum bearings should last for quite some time if properly lubricated and not exposed to atmospheric conditions for any lenght of time.
5. What does the rest of the machine look like ?
6. Clean up kit if you do decide to reassemble should be installed.

Hard to tell the condition from a picture in this case.

Did you ever figure out why that YK was losing oil and then getting it back at shutdown?

clean them up and mic them and see if they are in specs.

who cares if they are still usable? it is already open, replace them especially if they are questionable.

Some more pictures of chiller A,

Two YTJ-67 Compressors

I have two YT chillers used with R-11 refrigerant,
they were initially started up twenty six years ago,
for the past 7 years, they have been left unused, and now the customer wants to reuse them for their supermarket air conditioning,
I just had the compressors(YTJ-67) disassembled,
both compressors' bearings and seals(Balance piston and eye seals) have some scrtches and scuff marks on the inner surface, and on the outward surface, there seem to be corrosions that I suspect it was caused by moistures in the refrigerant system and no lubrication(as I mentioned these two chillers have been put idle for 7years),
My questions are:
1. are these bearings still useable?
2. what is the life span for Aluminum Alloy bearings used in York centrifugal compressor?
Any advice will be much appreciated.