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Manufacturing Problems

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 Weight.
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 be guaranteed.
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 Specification

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.

Repairing Mazak

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.