Tips – Cooling System

 

Cooling System

Types of Fans (to avoid!)
Fan Removal
Engine Water Outlet Mounting Lugs
Coolants

 

Types of Fans (to avoid!)

A problem which some members are aware of is the Model A fan.  Members new to the movement may not be aware of the potential disaster when they destruct.  Original fans can be a two blade or a four blade.  Both of these can be a potential disaster.  The original two blade is made with two separate metal layers joined to make one which has some air space between them.  This space captures moisture and over the eighty years, rust and vibration have weakened the metal.  Eventually with use, one end of the blade will detach.  This flying piece can destroy the radiator, badly damage the bonnet or harm you if you happen to be working on the engine bay with the engine running.  Not often, but over the years a few of our Club members have had their fan cause damage.

The original four blade fan can also be a disaster.  It has two separate metal blades which have four steel rivets holding it together.  The problem here is that over the years the vibration has cracked one or several of these rivets and it is only a matter of time before they let go and the two blades fly around inside the closed bonnet doing lots of damage.

The above photos were taken off Facebook.  I also read on Facebook of a Model A owner in the USA who had an after market single blade aluminium fan throw a blade.  He did state that it had been in service since 1980 and suggested that the early reproductions perhaps weren’t as well made as today’s.

Suggestion to avoid:

Keep an eye on your fan and look for cracking or loose rivets and avoid turning your engine by the fan.

I always balance my fan regardless of which fan I use (original or reproduction).  I haven’t used a four blade but used an original two blade for 20 years and now both of my Model As have reproduction two blades.

Place two equal height small angle iron pieces on a levelled, stable surface and place the water pump shaft with fan attached, on them.  File a small amount off the end of the heavy blade end until the assembly stays in the position you place it (it no longer turns to the heaviest blade).  I did find filing off an original, lead to me having to oxy weld the two metal layers on that end back together, dress the weld and file some more!

The fan needs to be bolted on securely.  I didn’t have a fan handy for this photo.

Alan Jeffree, MARC WA Newsletter May/June 2015
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Fan Removal

The taper lock between the water pump shaft and the fan may result in difficulty in removing the fan from the shaft.  Pullers and knock off tools are available but the following technique may be used to remove the fan.

After removing the split pin and nut, thread a standard 7/16th inch 20 TPI (UNF) hexagonal nut onto your shaft about half way into the nut.  Screw a 7/16th inch 20 TPI bolt about one inch in length into the nut and hard against the end of the shaft.

Holding the fan blade centre boss by hand give the head of the bolt several taps with a hammer and the fan should come free.  If it is stubborn then application of heat using a hot air gun to the centre boss should allow to fan to come free.

John Moorehead, MARC WA Newsletter Aug 2013
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Engine Water Outlet Mounting Lug Damage

The water outlet at the front of the head is secured by the two head studs and hence the nuts are tensioned to 55 ft.lbs.  It is not uncommon for one of the two mounting lugs to crack during the tightening of the securing nuts.  The main reason is that the thick paper gasket supplied by some companies results in uneven forces at the ends of the outlet lugs.  The section of the gasket beneath the lugs is compressed.  The section in the centre of the gasket remains thicker.  Originally Ford used a composite copper gasket for this application.

There is an easy way to prevent cracking of the mounting lugs and that is to machine or file the mounting surface of the outlet perfectly flat.  Then using a mill file, file the mating boss on the head flat.  You can then use a thin paper gasket and good quality sealant (sparingly) to fit the outlet without the fear of damaging the mounting lugs, or just use the sealant without any gasket at all.

Whilst other techniques may be employed, such as extra packing under the ends of the lugs to provide an even support, the above method has been found to work well.

John Moorehead, MARC WA Newsletter March 2018
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Coolants

At the time the Model A was manufactured, water with maybe some soluble oil was the coolant in common use.  Water has excellent heat transfer characteristics, however corrosion products (particularly with ferrous metals) is a problem.

Over the years manufacturers have developed specialised coolants with various additives for the vehicle engine/radiator cooling system.  There are two types of coolants:

  • Type A Coolants with inhibitors, anti-freeze, anti-boil additives based on water and glycol.
  • Type B Coolants typically has no anti-freeze or anti-boil performance and are essentially inhibitors only.

More recently the formulations of the coolants have changed to take into account the amount of aluminium or similar alloys used in modern vehicles.  One of the additives is identified as OAT (Organic Acid Technology) which works well in late model cars.  However this product may not be suitable for older cars, say greater than 10 years old.  In vehicles such as our Model A, these new additives may attack the gaskets and gasket cements.  Also it has been found that the acid coolant may actually destroy soldered joints in the older type radiators.

The solution for our older cars, is to use a product with IAT (inorganic acid technology) if anti-freeze performance is required.  In WA, the requirement for anti-freeze is not usually an issue.  Some manufacturers supply a coolant for older vehicles eg, Penrite Classic Coolant and Nulon Ultra Kool for pre-1984 vehicles.  If required, these coolants should always be prepared with demineralised water.  The main performance characteristic of these products is as a coolant and inhibitor to prevent corrosion.  The high percentage of water ensures maximum heat transfer.

John Moorehead, MARC WA Newsletter Aug/Sept 2018
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