Date: Sun, 20 Sep 2015 10:06:04 -0400
Reply-To: Edward Maglott <emaglott3@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Edward Maglott <emaglott3@GMAIL.COM>
Subject: Re: Friday LVC: lubing old electric motors
In-Reply-To: <201509191854.t8JIsOEX020438@mail106c45.carrierzone.com>
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Thanks for the tips everybody. It's pretty much what I've been doing but
gives me some ideas for those motors I want to go to extra lengths to keep
going for the long term. I've got a couple old household fans that are
worth that effort. A nice heavy metal retro looking Vornado is one, and a
little oscillator from my childhood. The immediate need is an electric
chainsaw. It's been making that horrible chatter for a while when it is
slowing down to a stop. It belongs to some friends and I finally got it
from them to do a little rehab on it to get a little more life out of it.
The brushes are also worn to the point you have to shake it to get it to
start lol.
This also explains my work on my vanagon front blower via the mullendore
port technique. I sprayed all kinds of stuff in that bearing but it didn't
seem to help. PB blaster, WD40, triflow. I gave up and resigned that I'd
need to pull the dash and replace it eventually. It still worked, but was
noisy. Then, after some time, voila, it started working smooth and quiet!
So I assume all the oil/solvent took a while to work in there, soften
deposits and get that bearing in better shape.
In other VW electric motor news... My 2002 Golf TDI has 2 fans on the
radiator, big and small. The big one stopped working and I didn't even
notice it. I had noticed a drop in AC performance in very hot weather and
assumed that the system was just deteriorating after 240k miles and all
those years. Then I noticed that it was really just lower performance when
the car was stopped. Looked under the hood and yep, only the small fan was
running. The coolant temp never got elevated, so I guess there is plenty
of surplus capacity in the cooling system. I shopped for a replacement
fan, OEM was about $120 with shipping. Then I looked at Rock Auto and they
had a "mystery brand" offer for $50 including shipping. notes said it was
probably a discontinued model or something like that. Rolled the dice on
that and it turned out to be Meyle in nice original box. woo hoo. Anyway,
I took apart the old fan for analysis and the plastic holder for the
brushes was totally melted and glommed onto the commutator. This was
causing resistance in the rotation so I'm not sure if the bearings went bad
first or something just happened in that assembly. the bearings looked ok
but by the time I got in there to that point I didn't try to put it back
together to see.
Edward
On Sat, Sep 19, 2015 at 2:54 PM, David Beierl <dbeierl@attglobal.net> wrote:
> At 08:25 PM 9/18/2015, Edward Maglott wrote:
>
>> This seems like a good question for David B. and others on this list. I
>> like to fix old things up and use them or repurpose them. Old fans are
>> one of those things. Usually they are AC fans you plug in to the wall,
>> but this probably also applies to the DC fans in our vanagons. I can take
>> them apart and get to the bearings, which are usually just a metal shaft in
>> a metal bushing. I clean up the surfaces and lube them with some handy
>> oil but this fix usually only lasts a little while. What is the best lube
>> to use for this situation to get the most "revive time" between service
>> intervals? I assume the bearing is actually worn and not fitting
>> correctly and can never really be right again. Ideas?
>> Edward
>>
>
> If the bushing is worn you'll know because it will chatter, which is to
> say the shaft will roll around the enlarged opening instead of rotating
> smoothly in it. It will emit a mechanical shriek of agony that on
> something more powerful than a CPU fan will freeze your blood. This tends
> to happen to sleeve-bearing computer fans after a longish time, and to your
> average Black & Decker-grade "Skilsaw" or similar after what seems like
> about an hour of use. Short of replacing the bushing (which on the power
> tool you probably can) you can only pump the oil to it, a drop or three
> before each use if necessary. Computer fans will probably keep going for
> months after you peel off the label and flood the bearing, then stick the
> label back down. 30-wt non-detergent oil for the saw, machine oil or 10-wt
> non-detergent for the fans (10-wt non-detergent for the saw, light machine
> oil for the fans if they're not chattering).
>
> Otherwise, the bearing has either gotten dry or the lube has stiffened up
> or foreign material has gotten in. Most "permanently" lubricated sleeve
> bearings are porous sintered bronze permeated with oil (the ones on the
> Bosch blower motors are sintered steel, apparently). Ideally you soak them
> in hot oil (?180F?) for half an hour. When that's not practical, do the
> best you can. I've gotten years of service from seized Bosch heater
> blowers (that had not been cooked by leaving them powered) by working them
> free with multiple changes of Marvel Mystery Oil which has some solvent in
> it, then running them unloaded on the bench for a couple days with frequent
> attention -- soak up the oil, add new, examine the rag. Once the MMO
> starts coming back the same color it went it, shift to name-brand sewing
> machine oil (which is simply a high-grade light machine oil). On the Bosch
> blower in particular there are large felt pads pressed against the bearings
> as oil reservoirs. Similar may or may not be present on other motors.
> Next Bosch blower I look at I'll think about re-oiling it after freeing it
> up by suspending the end of the motor in hot oil. The back end where
> that's more practical (open frame, no protruding shaft) is also the bearing
> that takes the beating on those blowers from whatever grit is in the air
> stream. Adding a cap to it seems advisable.
>
> Yrs,
> d
>
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