Alternator screeching when under load

[Keith Lawyer]

The alt on my '90 200 screamed all the time.  I believe the pitch would
change under load somewhat.  I'm sure it was bearings.  A new alt
(albeit expensive Bosch) solved the problem.

Keith L

>>> <radek at istar.ca> 12/30/04 12:57PM >>>
Hello group, need your help.

My 88 90Q has been doing this for some time now.  When the electrical
load increases (like
having the 
headlights on and switching on defrost) the alternator would start
making the most awful,
high-pitched 
screeching noise and stop charging (voltmeter drops from 14V to 12V or
so).  First, I
suspected the belt 
slipping but tightening it would not solve the problem.  Next, I
suspected high electrical
resistance so I 
took out the alternator, removed the voltage regulator, checked the
brushes and cleaned
all the 
contacts.  Still no help.  Yesterday the screeeching got worse and on
my way back from
work the belt 
broke.