View Full Version : Possible reasons for a Compressor Crank Shaft break

03-07-2017, 11:19 AM
Recently we inspected a compressor (under warranty) with vibration and loud noise. Upon opening we found that the crank shaft is completely broken into two pieces.

But surprisingly there is no damage or even a scratch on the cylinders/piston. What could be the reason? Is it a manufacturing defect?

Application : Dairy Cold Room Chiller
Condensing Unit : Carrier CRL400 CX (Air Cooled)
Compressor : Bitzer 2 CES 4 (Semi Hermetic)
Refrigerant : R22
Operation Time before failure : 3 months

monkey spanners
03-07-2017, 04:30 PM
Bearing surfaces look like they have copper plating.

03-07-2017, 05:04 PM
Copper plating is a consequence of moisture mixed in with the R22.

My guess is you have a moisture contaminated system which has suffered with liquid flood back.
It will be interesting as to how bitzer react when you try and claim warranty.
A good system would take years to produce that much Copper Plating.
Was the compressor installed 3 months ago to replace one that failed.
Which is my guess.
Or are you saying this is from a new install of 3 months ago!!
Either way someone needs a kick up the backside.

That comp failed not because it was faulty but because of how it was being used.

Sorry I would be questioning the maintenance guys.
You have not been buying cheap R22 recently have you?

08-07-2017, 01:15 PM
Hi grizzly, yes this compressor was gone within 3 months of new installation. You mean to say there is moisture and hence the system failed? But how come only crank case is affected? The main surprise is pistons/cylinders/connecting rods are intact. Hence cant figure out the possiblity of liquid floodback as well.

The manufacturer is reviewing the case and you mean to say there is no chance to claim under warranty?

08-07-2017, 02:21 PM
One look at the photograph showing copper plating and and signs of high temperature at bottom of photograph coupled with the compressor oil being suspect now due to moisture in system and it likely the manufacturer would tell you it was not installed to their specification and therefore would void any warranty. Which manufacturer are you hoping to get warranty from, Carrier Refrigeration or Bitzer ? Good luck with that.

Glenn Moore
08-07-2017, 08:37 PM
All above comments are relevant to your problem,. the copper plating is due to a high moisture content in the refrigerant and the oil . The crankshaft journals tend to copper plate quite easily due to the hot heavy friction bearing loads which speeds up the plating process, The fractured crankshaft is normally caused by liquid slugging where the cylinder fills with liquid but the motor continues to spin the crank to its fracture point. If you go to the Danfoss web site and look for " Why Compressors Fail" by Glenn Moore part 3 explains why your crankshaft broke or you can find them on Google There are 9 articles on the subject

10-07-2017, 05:55 AM
If you go to the Danfoss web site and look for " Why Compressors Fail" by Glenn Moore part 3 explains why your crankshaft broke or you can find them on Google There are 9 articles on the subject

I can highly recommend the series of Articles that Glenn mentions above.
He can hardly praise them as he wrote them!
Worth a read or re-read.

10-07-2017, 03:31 PM
Vacuum, vacuum, vacuum...
Never cut corners when you replacing any compressor.
Only good, deep and long vacuum can protect the compressor. And afterwards always carry an oil check for moisture and acidity.

11-07-2017, 11:42 PM
Is there a check valve in the discharge line and if so is it holding.
As Glenn said liquid will break crankshafts.

12-07-2017, 02:43 AM
First and foremost why did the original fail? The answer may be in the detail that would be my main priority,replacing a failed compressor is easy finding the reason for failure is paramount failure to find the reason can prove costly,was the txv changed contactor changed? acidic test done ,3 months after replacement failure somethings wrong!

26-07-2017, 12:52 PM
I do agree with all of the above, good hygenic procedures should always be followed, I do see signs that some sort of 'jarring' or 'juddering' has been occurring too, what was the condition of the valve gear on the top end, were crankcase heaters functioning, was refrigerant charge correct, is the operation of the Expansion valve correct? Did anything unusual occur prior to failure on site, power cuts, etc. It could also be 'transient torque' as that can snap cranks, is the starter functioning correctly?

01-08-2017, 08:49 AM
Thank you for all the posts. We have shared the costs with the manufacturer and installation contractor. The installer is advised to follow proper vacuuming of system and measures to ensure good installation and operation.