[DMCForum] Re: Cooling system failure

["Walter Coe" <Whalt@xxxxxxx>]

> How do I drain whatever coolant is left in my system?

The original radiators do not have petcocks, but many of the
replacement ones do.  For one without, just pull off the
lower hose being careful not to break the plastic nipple
(for radiators that have plastic tanks.)  If you do this
laying down, keep your mouth closed and cover your eyes.
Coolant is yummy; BTW, but try not to experience this first
hand.  The connection has very little clearance, so you may
need to take both clamps off the hose and then slide the
hose up the pipe.  If you are buying parts from Toby, I
recommend the inline valve he sells that goes on the upper
bleed line of the radiator.  In either case, be sure to burp
the line or you could have air stuck in there.

The engine has two coolant drain plugs -- one on each side
of the engine.  They are the same style as the oil drain
plug.  You will need the proper socket with a long extension
to get to them.  If you really want to flush the engine
without having to properly dispose of (or recycle) lots of
diluted coolant, removing these plugs is the way to go.
They use the same copper crush washers as the oil drain plug
and should not be reused.  These are common autoparts store
items.  Dont use the hollow-type crush washers as these can
leak with coolant but aren't as bad for leaking oil.
Instead use crush washers made from thick copper sheet
metal.  Consider coating the plugs with something that will
keep coolant off of the threads and is thick & heat tolerant
enough to keep it from washing out.  This will make the
plugs easier to remove next time.  What doesn't work here is
anti-seize or heavy grease.  Teflon tape may work but be
careful with it.  I just tried an engine with a type of
crayon that NAPA sells to coat spark plug threads.  I'll
know how well it works the next time I drain the coolant.

> How many gallons of coolant does the car hold around?

The spec is in the service manual.  I completely fill the
system with distilled water (approximately 3 gallons) &
pressure test to 15 psi for 15 minutes.  Again, the manual
gives the specs for the pressure test (if you have such a
fixture.)  It is also good to run the engine, make sure all
the air is out, get it hot and look for drips as it cools
down.  Then I add 1.5 gallons of antifreeze to the header
bottle while leaving the bleeder screw open (or self-bleeder
hose disconnected.)  The point of entry of the new
antifreeze is far enough away from the drain point that you
wont loose any new antifreeze this way.  (Do it without the
engine running!).  The end result is a topped off system of
50% water & 50% antifreeze.

> What coolant is recommended?

The service manual gives some guidelines.  The main thing is
to stay away from Dex-Cool compatible coolants.  The reason
is that the chemistry is not compatible with lead solder
contained in the heater core and replacement brass
radiators.  If you use it anyway, you will develops leaks
because of it.  I like to use the regular green Prestone.

> I am sure it doesnt really matter,
but what oil is recommended for this car (brand and blend)?

Dont get us started on that!  Everyone has their own
opinion.  Some like synthetic/some dont.  Some like
thick/others like thin, etc, etc.

My 'opinion' is to use Castrol since so many people love the
brake fluid they sell.  I stay away from synthetic because
it is expensive and tends to leak easier.  The PRV crank
case is based on an old diesel configuration, so high-tech
oil isn't going to make a big difference like it could in a
higher revving engine.  Choose an oil that has a small
range.  For example choose 15W-40 over 10W-50.  The reason
is that the smaller range oil has less additives to make it
thicken up as temperature changes.  Less additives means
less crap to break down or precipitate out of suspension.

As part of your shopping list, consider buying a new heater
hose "T".  I like the brass one that Bryan Pearce sells (the
guy who makes the SS frames.)  If you have had leaky
connections around the original aluminum ones, it can be
pitted so bad that the fitting itself will have holes.

Walt

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