Metal Particles in Lube Oil

[wr180561]

We have a MaK diesel engine running for approximately 10,000 hours. Recently we noted some metal particles coming to the lube oil drain tank (the engine is fitted with a dry sump). The oil analysis showed that the metal particles are Aluminum. Although we have inspected all the internal parts of the engine (all bearings, drive gears, lube oil pump bearings and rocker arms) but with no avail.

Can anyone tell me where else this aluminum particles would be coming from ? Thanks. WR.

 

[GregLocock]

What aluminium parts is the oil in contact with? The manufacturer will be able to tell you. A chemical analysis of the aluminium should narrow the possibilities down.

Cheers

Greg Locock

 

[patprimmer]

It seems to obvious, but you did not mention pistons in your check list.

Regards
pat pprimmer@acay.com.au
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[wr180561]

Pistons on this engine are made of Cast Iron not Aluminum. Thanks. WR.

 

[PEW]

Could it be a bearing outer race spinning in the crankcase?

 

[wr180561]

Now after more investigations we suspect the thrust bearing being the reason for all these metal particles. It is made of Aluminium and we recently had the coupling between the engine and the generator replaced. In fact it seems that the axial clearance between the coupling and the flywheel had not been set properly caused the thrust bearing to bind against the main bearing of cylinder no 1. However the thrust bearing is being dismantled now & Will keep you posted.


Thanks for your valuable responses. WR

 

[wr180561]

The trust bearing was removed and inspected but nothing seems to be wrong with it. In fact there no sign of wear or tear on it and its thickness is still the same as a new one. However, the thrust bearing should limit the end play between the crankshaft and the first main bearing. The question here is while in operation will the thrust bearing clearance be equal in both sides or could it be 0 at one side and maximum at the other side ? can anyone help to answer this question. Thanks WR.

 

[patdaly]

Yes, by the very definition of a thrust bearing, you would have, at least in operation, the maximum clearance on one side, and in essence 0 clearance on the other.