Fowler Petrol Engine Resources
As a result of restoring and working
on several Fowler engines (mainly PA & PD) I am very familiar
with the problems which many Fowler engine owners encounter.
The main problem encountered relates
to the poor quality 'Mazak' type alloy castings used on many engines
for the following vital parts:-
1PA 6 - Crankcase Door*
1PA 8 - Oil Filler Body*
1PA 9 - Oil Filler Cover
1PA 42 - Tappet Block*
1PA 60 - Magneto Gear*
1PA 63 - Governor Gear*
1PA 64 - Governor Weights*
1PA 100 - Camshaft Bearings*
1PA 385 - Inlet Manifold
1PA 500 - Complete Governor/Magneto Housing*
1PA 501 - Timing Gear Cover
1PA 1250 - Oil Dip Tray
On engines found with Mazak alloy
parts it is often the items marked with a * that are found to
be defective, however this may vary in practice. The photos below
illustrate typical parts/problems which may be encountered by
the restorer, click on the thumbnails to enlarge.
Selection of parts, Inlet Manifold, Camshaft
Bearing remains, Oil Filler (flange remains) and Governor
Magneto Gears - Mazak on the left, Steel
on the right. This Mazak gear would most definitely fail
in use and would probably damage the engine beyond repair
as a result.
Badly expanded/warped Tappet Block, left
hand tappet is siezed solid.
Badly cracked/expanded Governor Weight,
again re-use could cause serious damage as failure would
Badly warped and very brittle crankcase
door, not salvageable.
Mazak timing gear cover, usually fails
around the bolt holes and governor level lugs. Unmachined
raw cast iron replica on the left.
An attempt at Aluminium Casting, reasonably successful !
Mazak is a Zinc based alloy which was commonly used
in die casting and high pressure moulding processes. Dinky Toys
and Hornby used Mazak extensively in the moulding of model car
bodies and train engine wheels due to the high friction properties
which made it excellent for traction wheels of model trains !
The material was also known as Zamak in certain
countries and typically consisted of 95% Zinc, 4% Aluminium, 1%
Copper. Some grades also contained different proportions to including
Magnesium in the mix.
Unfortunately many early Mazak products have not
withstood the test of time and suffer from cracking, brittleness,
crumbling and general weakening. Model toy collectors often encounter
model trains with wheels which have disintegrated or warped beyond
repair. The root of this problem appears to be caused by the crystalisation
and separation of the constituent materials that go together to
make this alloy. Poor quality control during manufacture is the
likely cause of the impurities in the original castings, perhaps
as a result of inferior ingredients or contaminents in the mix.
It has been suggested that environmental conditions are a trigger
for the material to start breaking down, this could be a result
of exposure to moisture or heat which in turn causes the oxidisdation
of materials within the alloy resulting in the separation, expansion
and hence 'explosion' of cast Mazak parts. This would seem a likely
answer but one which requires to be verified.
Mazak is a very difficult material to even work
with when in good condition let alone in a poor weak state. Parts
which are critical to the operation of the engine are in my opinion
impossible to repair if cracking and warping has occured. Using
a defective magneto gear could result in the gear shattering in
operation with metal shards causing untold damage to the engine.
The best option is to either obtain steel or cast iron original
replacements from a donor engine or have new parts made or cast
(but this will be expensive).
I have managed to repair non-load bearing Mazak
parts through the use of products such as JB Weld or Plastic Padding
Chemical Metal. I have only had experience of repairing oil fillers
and inlet manifols in this manner and would be reluctant to carry
out such a repair on any other parts as this method is merely
a means of cementing broken parts together - the weakened metal
will still be underneath.
A number of 'welding' products can be found advertised
on the internet claiming to successfully repair Mazak and other
similar materials. In certain situations this may be fine however
a magneto gear suffering from many thousands of tiny cracks will
be impossible to repair successfully. I would suggest that such
'welding' solutions be applicable for light applications such
as repairing snapped oil fillers etc. Even so, I would think the
use of epoxy type products would be easier to use with a higher
chance of success and minimal damage to the original casting.
Further Information on Mazak Alloys
For more information on dealing with Mazak Alloy
parts please see Restoration Tips.