At 03:25 PM 1/15/2012, Jim Felder wrote:
>Is there a way to get�or any point in getting�behind the blower end of the
>frame and armature?

All blower motors that I've freed up have lasted 
years without further problems.

Procedure as follows:   see 
https://picasaweb.google.com/dbeierl/VanagonAnatomyOfABOSCHHeaterBlowerMotor?authuser=0&feat=directlink 
for photos of the motor.

Note - it's been a while since I've done this, so I may be off in some detail.

1) Split blower housing by releasing tabs.

2) remove wire clips holding motor into plastic 
sleeve.  Mark the motor orientation in the 
housing.  Place housing on the open jaws of a 
vise or other support so that the jaws support 
the motor sleeve but don't cover the edge of the 
motor.  Remember you will need room for the motor to fall from the sleeve.

3) Press the blower wheel down and verify that 
the motor moves reasonably easily in the 
sleeve.  Get the edges of the motor past the vise 
jaws and adjust vise for maximum support.

4) Note how far the blower is inserted onto the 
shaft.  Using a drift and large hammer, tap the 
motor shaft out of the blower wheel.  Make *sure* 
that the edge of the motor isn't catching.  As 
you near the end the shaft will drive 
easier.  Get a hand underneath to catch the motor 
as it falls out, as it will be damaged if it 
drops end-first onto a hard surface.  Set the 
wheel aside, being careful not to dislodge any 
metal balancing clips on the blades.

5) Examine motor.  All the ones I fixed had 
brushes worn 1/4 or less and were seized 
up.  Commutators looked good.   A motor that 
screams horribly (bearing chatter) when started 
needs new bearings and cannot be repaired in practical terms.

6) Drop Marvel Mystery Oil or similar outside 
each end and work the shaft in and out and rotate 
it.  Wipe off crud as it emerges and re-oil.  Run 
the motor for a few seconds.  Wiggle, wipe, oil, 
run etc. for several cycles until no further crud 
emerges.  When motor turns sweetly...

7) Soak up MMO as much as possible.  Lube inside 
and outside of shaft with light machine oil 
(Supco MO98 turbine oil is good), and fill the 
felt ring inside each bearing with oil (see photos).

8) Clean and dry commutator.  Brake cleaner on a 
rag is good.  If necessary (probably not) sand 
lightly with very fine sandpaper (800 grit is 
probably pretty good).  Do not use emery.  Gently 
scrape any junk from between the commutator 
segments with a soft tool that will not scratch 
or deform the copper.  Clean  and dry again if needed.

9) Run motor on the bench for a couple days, 
checking periodically.  If more crud comes out 
wipe it from inside and outside and add clean 
oil.  There should not be much sparking at the 
commutator - trails of sparks indicate conductive 
material still between the commutator segments.

10) Observing orientation, press motor back into the housing.

11) Rest the motor shaft on a hard heavy surface 
and use a hammer and block of wood to tap the 
blower wheel back onto the shaft.  Set the depth 
the same way as before it was removed.

12) Replace the wire clips holding the motor in.

13) Before closing up the housing, run the motor 
and make sure all is well and wheel is balanced.  Close up the housing.

14 - Load test motor.  The Bosch blowers I've 
tested draw about twelve amps from a fully 
charged battery (engine not running/charger not charging).

[15) - glue protective cap over the end of the 
motor.  If you cover the entire end, leave a hole for ventilation.]

>Now it runs like a top, but I would like to know more about the condition,
>like how much current should it be drawing. How do I accomplish that? I
>have voltmeters but need to improve my ability to use them.

You need a meter that will measure more than 10 
amps DC.   Place it in series with one lead to 
the motor.  If you don't have access to such a 
meter you can build a shunt out of copper wire 
and use your 200 mV digital voltmeter to measure 
across it.  More later if you need it.

>Finally, is the front blower motor different from the rear.

Yep.  Rear is smaller.

Yours,
David