[alfa] Re: GTV6 Belt Tensioner

[Joe Elliott <jee@xxxxxxxxxxxxxx>]

At 6:02 PM +0000 12/4/04, alfa-digest wrote:
> Question 1 - Why does this keep happening?  Especially with no valve damage.
> Question 2 - Is the hydraulic tensioner inherently bad?  If so, why?  Only
> leaking?
> Question 3 - Are there two different types of mechanical tensioners?  If so,
> which is best and where do you get the better one?
> Question 4 - How do I reverse the hard locking loctite that I used?  Heat?
1 - Defective tensioner, and luck, respectively.

2 - In a word, no.  It does leak, but it's hard
to argue that that's worse than bent valves.  If
you want to be nitpicky, its behavior is non
ideal in that it will apply slightly more tension
to the belt when the engine is hot.  Otherwise,
it uses two sturdy coil springs to apply
nearly-constant tension to the belt at all times,
except for startup, when it applies a little more
just to be safe.  The main features of the
hydraulic aspect are the afformentioned extra
tension on startup, and a reduction in tension
that's roughly proportional to engine speed, to
account for the fact that the timing belt has to
transmit less torque to the valvetrain at higher
engine speeds.

3 - There's only the one ARDONA thermomechanical
tensioner, although people will argue that
certain manufacturing batches are more likely to
be defective than others.  But there's also Tom
Zat's Staybelt tensioner, which is totally fixed
and does nothing to keep tension constant as the
motor expands (that said, I used one for 26,000
miles with a couple of scares, but no actual
failures, and other people have mostly positive
things to say about it).  My personal preference
is to use a hydraulic tensioner with the
hydraulic aspect disabled.  This puts slightly
more tension on the belt than either official
solution, but it's considerably less than the
tension that a Zat tensioner puts on a warm
engine, and the tension is also nearly constant,
so I have no problem relying on it for 30,000
miles.  It also doesn't leak.

4 - In a word, yes.  It depends on which Loctite
you used (hopefully not a heat-resistant
formulation).  For #270, for example, they say
"Apply localized heat to nut or bolt to
approximately 2500C. Disassemble while hot."

Joe Elliott
'82 GTV-6 (with non-hydraulic hydraulic tensioner)
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