The 2 Litre Nord-Engine and its carburettors
A problem that plagues the owners of the older Alfa's, mainly the owners of the 105
models, is the reliability of the cylinderhead gasket. I am not going to spend too much
of your time in explaining how you replace the gasket, too much has been written on this
subject, my small contribution is to serve only as supplementary info. More on the
matter is listed below. What I would like to describe, are the various methods that
are around to help you keep your gasket live longer.
I would like to describe the reasons why gaskets give up their elasticity and start to
leak. First of all it depends on the sealing surface, or should I say the amount of
surface on the motorblock. Secondly, the heat transfer between the various areas of the
cylinderblock and the cylinderhead.The cylinderhead has a rather large problem, on
the one side we have the exhaust manifold, this means here is the warmest area and then
we have the inlet manifold, here it's not too warm. Result is that the exhaust side of
the cylinderhead begins to warp, this is not very healthy for the gasket which with time
will loose it's elasticity and crack. The first signs are a very slight oil film on the
exhaust manifold, usually on the number 4 cylinder, if this is the case then it won't be
long till water starts to make it's way into the oil sump, then we are talking " milk".
"Milk" is usually noticed in the later stages, before this stage is reached you can check
by looking under the oil cap or even better under the cam cover. In the early stages you
might encounter a few water drops, this and the oil film on the manifold are the first
real warning that something is seriously wrong. Now is the time to change the gasket.
In contrast with other motors water does not or is very seldom found in the combustion
chamber. This is the reason why the old trick of looking for steam or water coming out
of the exhaust does not apply to Alfa's. Forget this method, even if your mechanic
swears by this method. Should these symptoms appear then there is something even more
seriously defect, like a cracked cylinderhead for example. Don't worry, this is a very
seldom event with Alfa motors.
Back to the cause of the water - oil mixture. The gasket is made up mainly from O-rings,
these in turn seal the oil flow between motorblock and cylinderhead. It is these that
are the cause of so much trouble. You can destroy the rings by just giving too much
gas when the motor is cold, "plop" and they've vanished. The sudden oil pressure is enough
to rip the old rings apart. The main cause of damage is the rather hot motor oil, this
lets the rings swell, this means, if I am correct, that the rings are bigger, therefore
taking up more space than before. When this happens it usually means the ring must move,
but where?. Seeing the ring is fixed into the gasket it is logical that the only way
is into the oil canal, this means that the ring is now a figure 8, this condition will
not last long as the ring will desintigrate due to the oil pressure and the high
temeratures. That is not all, the gasket is now wide open to the oil and we don't have
to be Einstein to realise what that means.
Apart from using only very good quality gaskets, I recommend those from Reintz, are
following tips helpful. The black Perbunan Š-rings that come with the gaskets can be
thrown in the bin. Instead we use rings that are composed of VitonŠ, of course with
the same dimensions. VitonŠ is a fluorine-rubber mixture, you can tell by the greenish
colour.This kind of ring is designed specially for use in high temperatures as well
as very destructive enviroments. Both of these conditions reign in your motor,
therefore the VitonŠ rings should always be used instead of the PerbunanŠ rings.
Using the new rings has helped somewhat, but to make sure that they stay put we can do
even more. In the 116 series is this small helper already at work. These helpers are
bushes, they are pressed into the motorblock and act as a guide for the cylinderhead,
they also help to hold the gasket in place, but most of all they keep the oil away
>from the rings.These bushes are made under the DIN standard DIN EN 28752, that means
they are always of good quality, which in turn means your problems are around 90%
solved. If you should have any questions don't be afraid to ask. You leave the bushes
looking around 2mm above the gasket so that the head sits. There are 2 versions, the
split version and the plain bush, the split bush fits better but has one weakness,
the PerbunanŠ-rings can even get sucked through the split, so please, please use the
VitonŠ-rings, it's worth the extra cash.
Now we can refit the cylinderhead. The extra work is negligible (fitting the bushes).
The extra costs are around 5,- Euro.The cylinderhead bolts are the fitted & tightened
as described in your workshop manual!!
As promised, here are some books that might be of assistance to the subject of cylinderheads for
those of you who can read German and for us Brits is the one at the bottom the only one of interest:
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Alfa-Romeo Giulia, Spider Owner's Workshop Manual (most models are illustrated
here); Autobook (Brookland's Books 1991); OWM 724; ISBN 0 85146 128X;
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German Book: Schrader-Motor-Technik; Alfa Romeo Giulia, Spider, Bertone GT 1962 - 1976;
Restaurierungsanleitung; Nachdruck der original Bucheli-Reparaturanleitung;
ISBN 3-922617-91-3; (z.Zt. nur antiquarisch erhältlich, einige
Alfa-Teilespezialisten haben aber noch Exemplare vorrätig); Anm.: die
Beschreibung der Arbeitsvorgänge ist sehr gut, die Datentabellen und
Drehmomente sind allerdings mit Vorsicht zu genießen.
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German Book: Reparaturleitfaden Alfa Romeo Giulia, Spider, Berlina, Bertone GT;
(Zusammenfassung der vielen Einzel-Werkstattanleitungen), erhältlich bei
Alfa-Romeo-Teilespezialisten); verläßlichste Drehmomenttabellen.
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German Book: Technische Daten und Hauptkontrollwerte (erhältlich für die meisten
Typen); für 2 Liter-Motor in o.g. Werk (Reparaturleitfaden) enthalten.
We recommend that you buy a spares catalogue for the particular model you are working on,
it always pays.
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Text: Martin N.
Translation: Dave
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