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Posts: 27
Reply with quote  #1 
I have seen some of my maintenance friends mixing small quantity of grease in lubricating oil of oil lubricated bearing. This is to minimize oil leak through oil seal . how far it is suggest able and how it effects vibration analysis of the bearing


Sr. Member
Posts: 647
Reply with quote  #2 
I've seen a lot of pump seal leaks and never heard of that solution.

Often the solutions are:
1 - check the oil level to make sure it's not maintained too high
1A - sometimes an oiler on the wrong side of the reservoir sense level falsely low due to pumping action of bearing
1B - sometimes there is a vacuum on reservoir that causes the oiler to overfeed. Check reservoir vents.  Consider closed-system oiler with equalizing line to oiler.
2 - check for excessive agitation/splashing/foaming within reservoir. 
3 - check assembly of seal. Check clearances if lab seal.  Check soft parts if applicable like Forsheda v-ring. Sometimes there is a component that floats axially that needs to be moved closer to the seal.

Adding grease seems like something that a farmer would try. I'm not saying it's not effective and side-effect-free (because I don't know anything about it)... it just doesn't seem like a standard approach. 


Sr. Member / Supporter
Posts: 216
Reply with quote  #3 
There is a grease called corn head grease that I believe Mobil manufactures, that is used in antique equipment, particularly old track equipment, that has a 000 viscosity. It is a pump able grease that turns liquid when it is heated up. It is used in old bottom rollers and similar applications, where wear is severe and/or seals are non existent. It will stay in place for a long time. However, I give you this information to show what EPete is alluding to, this is a farmer's fix.
Identify and correct the reason for the leakage. Then give the bearings the proper lubricant.
To answer the original question, if these are close clearance bearings or large bearings running at a speed above their recommended greaseable DN number, you'll see the normal change as the bearing runs with reduced lubrication. If they are just regular C3 bearings running at normal loads and speeds, I doubt you seeuch difference at all with vibes. If it is a gearbox, you'll probably see more effect on the gear teeth than the bearings.


Posts: 4
Reply with quote  #4 
Typically this is not a good practice, grease is a thickener (sponge) with oil added to it along with a few additives, the EP additives could have a negative effect with the balance of corrosion inhibitors, it would be better to repair the seal/shaft or in a emergency buy a thicker oil.
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