Cleaning hydraulic parts

["Graham Hilder" <graham.hilder@domain.elided>]

Greetings all,

A query please for those more experienced than me in the ways of chemistry =
and car maintenance (that means most of you..!).  I have often wondered =
why car manuals always specify to NOT use petrol for cleaning up any =
hydraulic parts (brake calipers, clutch cylinders, etc), but instead to =
use methylated spirits (or a commercial brake-cleaning product).=20

What is such bad news please about using petrol?  I hasten to add that I =
do listen to what the books say, and use meths, but when I'm trying to =
clean up a really greasy oily clutch slave or inboard caliper, which has =
been sitting next to a grubby engine or gearbox for years, I find the =
meths doesn't do a very good job of the exterior, and that petrol would be =
a lot better if I could use it.  Likewise for the hydraulic internals.... =
these can get very grubby inside if they've been running on dirty old =
brake fluid for untold years (because the PO never changed it),  and again =
petrol would be a much more powerful solvent than is the meths.  I do like =
to get the insides really clean before I re-assemble any hydraulic part, =
and sometimes meths just doesn't cut the mustard.

If I were to clean everything inside & outside with petrol, and then rinse =
out thoroughly with meths at the end, before I put the new seals anywhere =
near the cleaned part, would that be safe?=20
Alternatively, these commercial brake-clean products...... maybe I should =
be using these?  Do they really work? Will they clean up a greasy outside =
or are they only designed for internal cleaning?

All comments appreciated,
Best regards,
Graham in NZ
(77 Alfetta, 71 GTV, 82-82-84 Alfasuds)
(Maybe in a few more years I'll have done every single hydr seal on every =
one of these cars and won't have to worry about this again)

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End of alfa-digest V7 #1179
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