Changing fluids

[Scott Fisher <sefisher@xxxxxxxxx>]

Rob,

Just last Sunday, I completed changing out all the fluids on my daily
driver, having last done so on the Alfa last summer, so the procedure is
fresh.  It's largely the same on all vehicles, with the exception of
some cars with ABS -- did the '90 Spiders have ABS?  If so, I'll defer
to others for details.

Before you go shopping for the bits, I'd like to pass on some
recommendations:

1 - instead of DOT 3 fluid, get Castrol LMA GT.  It exceeds both DOT 3
*and* 4 specifications, which basically mean it has a higher boiling
temperature than DOT 3.  Also, the LMA stands for "low moisture
absorption."  Since your car gets very little use (30k miles in 8
years), this is an important safety and longevity feature, as it will
prevent corrosion inside the lines while the car is at rest.  It's also
only a shade more expensive than DOT 3, unlike the genuine racing and
high-performance stuff (silicone or ATE blue), and therefore represents
good value for low-use cars as well as hard-driven everyday cars.

2 - my current favorite brake bleeding apparatus is a little kit made by
the Lisle company.  It consists of what looks like a plastic Dixie cup
with a tight-fitting cap; the cap has two barb fitting sticking out the
top, one of which is connected to a barb fitting that sticks into the
cup.  Additionally, this kit comes with three L-adaptors that stick onto
the clear vinyl tube, to make a tight fit onto the bleed nipple. 
Basically, the purpose of this contraption is to serve as an air lock:
once you've made about three pumps with the brake, there's enough fluid
in the Dixie cup that air won't go back up the hose.

3 - if at all possible, this job is much easier with an assistant.  Yes,
I know there are various "one-man brake bleeding kits" available (the
Lisle kit just described is one such), but it's much easier with one
person to pump the pedal and another to turn the wrench and watch the
hose for color, condition and bubbles.

4 - there are those who swear by a device called the Mity-Vac.  This is
basically a hand-operated vacuum pump which you apply to the bleed
nipple; you then open the nipple and squeeze the pump, and fluid (plus
bubbles, crud and detritus) is drawn out.  I've never been able to get
really solid-feeling brakes with a Mity-Vac, while the brakes on the car
I did Sunday feel superb -- there's about an inch of pedal travel, after
which it's like standing on a brick and the car stops as though I'd
driven into a gravel pit.

Now, for the procedure for the brakes:

1.  Start with the wheel that's got the longest hydraulic line between
it and the master cylinder.  This will be one of the rears, but check
the rear axle to find out whether it's the right or the left.  (It's
*probably* RR, LR, RF, LF, but check the lines, or a good service
manual, to be sure for your car.)  If your '90 is like earlier Alfas,
there's a single flex hose coming off the chassis, and it tees into a
hard line that runs across the axle housing.  See which of those
sections of hard line is the longest, and bleed the wheel that's
connected to that one first.  Then do the other rear, then do the right
front, then the left front.  The sequence is important, as it helps
ensure that all bubbles and old fluid are completely purged from the
system.

2.  To bleed a circuit, jack up the corner you're working on and remove
the wheel.  (I'll assume you don't have a lift -- if you do, can I come
and work on my car at your house? :-)  I like to slip a box-end wrench
of the appropriate size over the bleed nipple, then put on the hose;
this helps keep the wrench in place during the procedure.

3.  When you've hooked up the bleeder kit, have your assistant pump the
pedal -- fairly slowly -- while you open the bleed nipple.  Watch the
color and condition of the brake fluid that's coming out the tube.  You
may be shocked -- it's probably dark, may have floating rust or other
contaminants in it, and if it's as bad as the stuff that came out of one
of my lines last Sunday, it may even have *chunks* of what look like
silicone sealer in it.  (Ick.)

4.  After about six or seven slow pumps, tighten the bleed nipple and
check the level of fluid in the master cylinder.  The most heartbreaking
thing in a typical brake (or clutch) bleeding job is the sucking sound
as you drain the master cylinder and draw air into your
almost-completely-bled circuit.

5.  Have your assistant keep pumping the pedal until the fluid that
comes out looks the same as the fluid going in: clean, free of crud, and
without bubbles.  That's the test.  Then go back to step 2 and repeat
for the next wheel in the sequence.

6.  When you've done all the wheels, it's time for the clutch.  I
typically do one particular thing different in bleeding clutches: 

  - I open the valve and tell the assistant, "Press."
  - I close the valve and tell the assistant, "Release."
  - I repeat the procedure until the fluid comes out clean.

Why do I do this?  To make sure the clutch slave doesn't suck up the old
fluid when releasing the pedal.  This may have been an anomaly of the
clutch circuits I learned on (all British, some in British cars and some
in Swedish cars), but it seems to yield a tighter, firmer clutch feel.

A few, generally minor cautions apply (minor compared to, say, brazing a
gas tank):

a.  Always be careful working under a car, as you will be for the clutch
procedure.  Never leave the car up on a jack alone, especially if it's
the jack that comes in the trunk of the car; always put a proper jack
stand on a good solid point of the chassis (where the suspension joins
is usually a safe place), chock the wheel *diagonally opposite* the
corner you're lifting, and give the car a good shaking before crawling
under it.

b.  Brake fluid is a fairly effective paint remover, so be careful about
touching your car's bodywork when you're doing this job.  (Brake fluid
is also toxic, so never siphon it by mouth.)  

c.  You almost literally can't be too anal-retentive when working on
brakes.  If you're not sure it's right, do it again until you're sure
it's right.  Fortunately, it's not rocket-science -- but it is critical.

Finally, how are your pads?  It's trivial to install new brake pads
while you're down there anyway (at least on the older ATE brake calipers
on my '67 it's trivial, removing a couple of pins and a spring is all it
takes; it can be more work if the calipers are stuck or frozen, as they
have been on the last couple of new-old car purchases I've made).  Alfa
pads are decent for driving around town, and with your car's low mileage
you may have years of life left in them.  But I recently upgraded first
my Alfa, then my daily-driver Audi, to Axxis MetalMaster pads and the
difference is dramatic in hard stops, especially in the third or fourth
hard stop in sequence (such as coming down a twisty mountain road or
driving in our perennial 65-0-65 mph traffic on the overcrowded Silicon
Valley freeways).  If you decide to go with the MetalMasters, write back
and ask about the bedding-in procedure, which is simple but important
for long pad life and maximum performance.

(And I think I've already mentioned this some months ago, but I find it
humorous that when I used to have British cars, MetalMasters were made
by Repco, but now that I have an Italian and a German car, they're made
by Axxis...)

- --Scott "If the Russians had entered Milan in 1945 instead of Berlin, 
         would it have been called the Aluminum Curtain?" Fisher

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End of alfa-digest V7 #35
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