I live on 2 acres with lots of oak trees, and mice and squirrels and
Alfas. Any Alfa that sits out ends up with acorns everywhere. They
especially end up between the cam on four clyinders.
I guess I drive my
Milano enough that no critters move in for the winter.
A mechanic at the
Alfa dealer have me hell years ago for running my Milano with the plastic
timing covers removed. I thought It looked "Cool." He thought newspapers or
all manner of road debris could get pulled up under the front of the car and
throw the timingbelt out of time.
I really wish Alfa had put chains on
the V-6 engines, especially the four cam 24 valve V-6. The 4 cam engine has
so many idlers and turns of the timing belt that it can be a maintainance
night mare.
That may be why I do not own one. Well that and the fact that
the owner of a 164 LS did not accept my offer of $1000 for his Alfa. It is
still for sale for $2000. The automatic is going out, but the engine is good,
if anyone is interested. It is here in Oklahoma City.
Ciao,
Russ Neely
________________________________
From: Richard C. Wagner <[email protected]>
To:
Alfa Digest <[email protected]>
Cc: [email protected];
[email protected]; [email protected]
Sent: Wed, February 10, 2010 12:43:38 PM
Subject: [alfa] V6 Timing Belt Tensioners
Rastinejad wrote:
> May be not
rats, but mice can sometimes carry acorns
> into the timing belt covers and I
have seen pieces of
> acorn shell in there. A piece of acorn shell on the belt
> can certainly cause a slip at the crank.
Indeed, now THERE is a novel
failure mode that none of us have ever mentioned before. Diminutive
saboteurs! And it really is possible, too. Imagine starting up one day with a
cache of mouse victuals in there, or a mouse himself. That could easily cause
a slip or a belt break.
Kowfy wrote:
> as far as the canadian or any other
tensioner goes i can't
> see why there would be any failure aside from a
bearing going
> south.
As Brian mentioned, there was a first iteration of the
mechanical tensioner that was reputed to have a stress riser somewhere at the
base of the spring. After some use, they would fail at that point, releasing
the tensioner's complete load on the belt and causing an instant, massive
slip.
But even with the updated (if it ever was, indeed, updated) mechanical
tensioner, there is another failure mode--and this can exist even if the
tensioner was installed correctly. If the tensioner is allowed to snap back,
from its tensioned position to its free position, the body of the tensioner
can put a small nick in the spring. That nick will act as a stress riser and
can eventually lead to the spring breaking at that point. I was informed about
this by one of the guys at Centerline, and I think that is what Steve was
alluding to when he stated:
> My theory is improper installation and even the
> Alfa factory bulletin sets up a mech to do it wrong
> by snapping tensioner
body over center and overtensioning
> outer thermal clutch spring.
And as
Steve says, the installation tech bulletin says to over-tension the belt, turn
the engine through two revolutions, and then set the tension by BACKING OFF
the tensioner. And if a ham-fisted mechanic simply lays into the tensioner
during the over-tension segment of the installation, who knows what lasting
affect that might have?
The biggest detriment I've found with the mechanical
tensioner is in the installation process. That is, getting it right. First,
it can ONLY be installed correctly with a mirror. There is no way, on the
GTV6 or the Milano, to get direct, parallax-free viewing of the tension
pointer or its indicator mark. So if you've set your tensioner without a
mirror, its tension will be wrong. Let me repeat that: if you've set the
tensioner without a mirror, its tension is wrong. (By the way, the
installation Tech Bulletin neglects to mention the use of a mirror.) Then,
there is the requirement to over-tension the unit, but not too much, and
rotate the engine through AT LEAST two revolutions to seat the belt. And
finally, the careful backing off of the tension while using a mirror to watch
the indicators. Now how many people, even experienced mechanics, have done it
that way? And if it's not done that way, it's inviting failure.
The last
time I installed a belt on my GTV6 I conducted a test. After installing per
the tech bulletin and using a mirror, I tried rotating the engine backwards.
That's right, backwards. At first I did it slowly and gently. And the belt
didn't slip. Eventually, I was laying into the handle of my 3/4-drive ratchet
with all of the assertiveness I could muster. Revolution after revolution, as
hard as I could do it. And the belt didn't slip. Not even a tooth. I
reported this to the digest, probably, four years ago or so.
My Mitsubishi
Mirage has a spring-loaded tensioner much like the Alfa mechanical tensioner.
But after the tension is set, the tensioner is locked down in that position.
On that engine, it can be done hot or cold, and amazingly, with the tension
set, I don't see a perceptible difference in tension when the engine is hot
and when the engine is cold. That engine has a steel block and a much shorter
belt, and that may have something to do with it. I wish we could do something
similar on our V6s, but with the aluminium heads and block, and with the long
belt path, there is just too much expansion and contraction involved. I sure
would feel better if someone could come up with a truly bullet-proof tensioner
that we could install and not worry about. The technique of using the
original tensioner, minus the hydraulic relief, may be a good one, but without
having some really good analysis, it's superiority over the mechanical
tensioner is still
unproven. Frustrating.
Rich Wagner
Montrose, CO, USA
'82 GTV6 --
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