unconvertable characters

My 8.0.1 database is using ISO_8859_8 encoding. When I select specific fields I get a warning:
WARNING: ignoring unconvertible ISO_8859_8 character 0x00c2

I now want to upgrade my database to 8.2.4 and change the encoding to UTF-8.
When the restore is done, I get the following errors:
pg_restore: restoring data for table "manufacturers_old"
pg_restore: [archiver (db)] Error from TOC entry 4836; 0 9479397 TABLE DATA manufacturers postgres
pg_restore: [archiver (db)] COPY failed: ERROR: character 0xc2 of encoding "ISO_8859_8" has no equivalent in "UTF8"
CONTEXT: COPY manufacturers_old, line 331

And no data is put into the table.
Is there a function I can use to replace the unconvertable charachters to blanks?
such as:
update manufacturers set manufacturername=replace(manufacturername,0x00c2,'')
(that query doesn't work.)
Or is there another way of doing it so that I just get rid of any characters that are not convertable?

Thank You
Sim