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Frigoriste
22-07-2014, 01:53 PM
Hi,

We are facing a problem on a compressor SMC106L. The crankshaft bearing was totally screwed. It has run for 6 years without problem. We replace the sleeve and it was worn again after 8 hours (see worn sleeve attached). We have made many tests on the oil system to be sure everything is working properly :

- Oil pressure at 65psi
- Pressure drop in filter at 5 psi
- Oil control working
- Oil cooler leak test is ok
- Thermostat, relay and solenoid valve on oil cooler are ok
- No unusual vibration on start-up
- All other parts seems fine

What else could have cause this issue?

Grizzly
22-07-2014, 04:31 PM
Hi Frigoriste.
No attached as yet?
Back to basics I am afraid, did you blow out the oil galleries within the crank?

What was the state of the bearing Journals?

I am guessing without any actual details..

But I would assume poor lubrication and or contamination / blockage.

Did you have to have the journals re-ground?

Did you replace all bearings Etc.?
Good luck.
Grizzly

RANGER1
22-07-2014, 09:35 PM
Hi,

We are facing a problem on a compressor SMC106L. The crankshaft bearing was totally screwed. It has run for 6 years without problem. We replace the sleeve and it was worn again after 8 hours (see worn sleeve attached). We have made many tests on the oil system to be sure everything is working properly :

- Oil pressure at 65psi
- Pressure drop in filter at 5 psi
- Oil control working
- Oil cooler leak test is ok
- Thermostat, relay and solenoid valve on oil cooler are ok
- No unusual vibration on start-up
- All other parts seems fine

What else could have cause this issue?

Frigoriste,
As per Grizzly's request also
Let us know a bit more of lead up to your current problem.
Also all running conditions & temperatures, also is it Mk 234 or 5
Assuming it's thermopump cooling from your description as well.

Have all valves plates ets been changed recently, or in the last 6 years of operation?
Which cylinder has failed, has bumper clearance & unloader's been checked & clearances noted as per manual description?
Are you using special plug to jack unloaders across on assembly & when installing head?

Are the small end bushes splash or pressure fed from crank?

HAve you carried out leak back test of valves to see if valves, seats, cylinder liner gaskets & internal relief are not leaking?

kiwi
03-08-2014, 09:46 AM
FLOODBACK. If everything is working this is about all that can do this so fast. Any smashed valves?

RANGER1
03-08-2014, 10:05 AM
FLOODBACK. If everything is working this is about all that can do this so fast. Any smashed valves?

Maybe, we had one but 106 S similar problem, water cooled though.
Other compressors running either side off common suction header, could never see any a
signs of a flood back & similar thing happened.
At one point it destroyed all 6 cylinders & pistons overnight, never convinced of real reason, but relief valve was knackered, opening prematurely.
Running OK now though.
Interesting how 1 big end shell failing, like Grizzly mentions about no oil on that journal or cylinder!

Magoo
04-08-2014, 12:48 AM
Interesting how one only shell failed, and the second so quickly. Possibly crank float thrust out of spec., but just one failing.
Is compressor belt driven or direct coupled.?

mbc
06-08-2014, 06:41 PM
it can happen for several reason .

your tolerance between crankcase and main bearing .
surface of crankcase .
oil pressure .
loosening nuts of oil pipe inside carter that caring oil to other side of compressor
check all holes oil passing in compressor and crankcase .
oil type and temperature of that.
your crankcase should be center between two main bearing and after assembling it can be move easily .

could your inform us how you measure your drop pressure after filter ?

RANGER1
06-08-2014, 08:32 PM
Have also seen on a Vilter 440, that conrod cannot centralise due to it fouling on inside of piston.
This loads up piston on bore & also possible to load up big end bearing.
Depending on how much misalignment, whether you notice it when turning compressor over.

We have not heard anything back from original post, so who knows!