Date registered: Oct 2007
Vehicle: 1992 500SEL
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In a private email I was queried about the possibility of soaking the bearing to eliminate squeaks. I'd like to comment on the failure mode observed.
I should have taken a better picture of the inside of the bearing. The one below is about as good an example as I've got. So I'll reference that one.
The peanut butter-like paste you see on my fingers is actually rust. The nylon bearing is in two halves. Each half is a cup that encases the bolt sleeve. The rust appears to be an accumulation of surface rust. What at first appeared to be pitting was actually layers of rust pressed to the surface. The nylon cups have grooves, which I presume are designed to draw the oxide out of the way. Frankly, they looked like they worked very well until the system was overwhelmed with the amount of rust accumulated.
While the system is considered "sealed," it's not. To make a true seal it would have to be impervious to the passage of air. Any air exposure to the steel is going to cause rust. No getting around it. I don't care how well you seal something to eliminate water, if it allows the passage of air it will condense when the temperature of the metal drops below the dew point of the air.
With that being said, the system is quite impenetrable to liquid. In my opinion, soaking it in a lubricant is a waste of time. Until the excessive rust oxides can be removed from the joint, and a proper grease applied to reduce the exposure to air (and the associated moisture that comes with air), adding a lubricant is simply changing the viscosity of the abrasive materials. The rust had the consistancy of pencil graphite dust. Imagine an oil mixed with grit. That's how they polish gems and stones. I've heard of people using a hypodermic needle to inject oil into the rubber seals, but I seriously believe it to be a waste of time and good grease.
Last edited by rightstuff4u; 09-14-2009 at 07:39 PM.