Some of the freeze plugs in my block have a button in them and are designed
to pop out. I never saw freeze plugs like that before but it makes sense.
Mike
----- Original Message -----
From: <karl.payne@gm.com>
To: <Fred_Katz@ci.sf.ca.us>
Cc: <datsun-roadsters@autox.team.net>
Sent: Monday, June 11, 2001 4:21 PM
Subject: Re: Steel core (not freeze) plugs
> Amigos,
> I would have to agree with steel core plugs. My experience in Mfg.
Engineering
> at Ford and GM says steel is more durable and dimensionally stable than
brass.
> The corrosion concern is solved by the zinc plating on the plug. This is
why we
> don't use brass plugs for production engines. Steel is cheaper too. ; - )
And
> we always apply anaerobic Loctite to the hole prior to pressing the plugs
in
> place.
> And now for my pet peeve: The PURPOSE of the large core holes is not to
protect
> the engine in case the coolant freezes as is commonly believed. There are
two
> reasons for these holes: 1. To allow the sand cores to be supported
during the
> casting process. (They "float" in molten iron and shift around, therefore
they
> must be secured)
> 2. To provide exit ports for casting sand. After the casting is
solidified,
> and the resin binder in the sand core has burned up, the castings go
through a
> "shakeout" line where pneumatic hammers pound the *bleep* out of them and
the
> sand pours out the holes. Without these holes they could never get all
the core
> sand out and our radiators would be very unhappy. Not to mention heater
cores.
>
> BTW, in the majority of cases when the engine freezes, the "freeze plugs"
don't
> pop out anyway.
>
> Just my $0.02.
>
> Karl Payne
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