Old style thermostat replacement

JBran - Your engine is a later OHV engine, as compared to Comtruck's sidevalve engine, and your thermostat is located exactly as you suggested, in the housing above the water pump, where the lower end of the top radiator hose is connected.

Modern thermostats are quite capable of being used as replacements for older style thermostats. The primary measurement is the diameter of the thermostat .. make sure your replacement is the same diameter as the old one, and is a neat fit in the housing, and is retained properly in position when the water outlet pipe is bolted on.

The secondary consideration is whether the new thermostat fits physically in the hole vacated by the old one. As most new-style thermostats are usually smaller than older styles, this isn't generally a problem.

The third consideration is the opening temperature. Many new thermostats open at 88

If you go to REPCO they have the thermostat book and will put your old thermostat over the drawing to get exact size.

You have a choice in most cases of high and normal flow and then various opening temperatures.

If you clean yours up you will see the opening temperature stamped on it - probably 150 or 160 degrees - just get one to match.

There is a really good chance yours is OK if you clean it up (wash and scrub it with a nail brush with say truck wash or even spray and wipe. Then put it in a glass of CLR rust and stain remover which you can buy at any Coles or Woolworths) until it is bright and shiny.

Empty the glass and pour in boiling water to see if it opens fully. If it does you can fine check it by using a small thermometer and gradually raising the water temperature until it starts to move which should be around the stamped opening temperature.

As Ron says get some serious radiator scour into your engine while you have the thermostat out and really give the radiator two or three really good back flushes (hose in the bottom radiator pipe). The 20 minute super stuff is great but follow the directions and don't leave it in overnight. The slow cleaner won't do the job for you.

Lang

JBran - Your engine is a later OHV engine, as compared to Comtruck's sidevalve engine, and your thermostat is located exactly as you suggested, in the housing above the water pump, where the lower end of the top radiator hose is connected.

Modern thermostats are quite capable of being used as replacements for older style thermostats. The primary measurement is the diameter of the thermostat .. make sure your replacement is the same diameter as the old one, and is a neat fit in the housing, and is retained properly in position when the water outlet pipe is bolted on.

The secondary consideration is whether the new thermostat fits physically in the hole vacated by the old one. As most new-style thermostats are usually smaller than older styles, this isn't generally a problem.

The third consideration is the opening temperature. Many new thermostats open at 88

JBran - Depending on how bad your system is, you can use any one of a dozen different cleaners. You need something that will clean up corrosion, without being too harsh.
A cleaner that is too harsh will make holes develop in the thinner material in the cooling system, such as the radiator.

You can buy commercial cooling system cleaners, which are generally quite mild. These cleaners are usually only used when cooling systems are not too rusty.

You can use a cupful of dishwasher powder, which is moderately alkaline. Many people prefer this simple treatment.
The dishwashing powder contains detergents that also helps release fine clay particles that are often associated with cooling system degradation.

You can use a cupful of caustic soda, which is strongly alkaline. Great care must be taken when using caustic soda, and safety equipment such as gloves and eye protection is highly recommended, to protect against skin and eye damage in the case of spillage.
Be aware that caustic soda eats away alloy components fairly rapidly. You don't want caustic soda in contact with alloy parts for more than couple of hours.

You can use about a cupful and a half of Citric acid. Citric acid comes in granulated form, looks like sugar, is very safe to use (it's a common food additive for preservation and is used in "bath bombs").
Citric acid cleans up corrosion in a very admirable fashion, without damaging the softer metals that may be part of cooling systems and engines (alloy components and solder).

You can use a cupful of Oxalic acid (available as a cleaning agent in granulated form in 500g containers).
Oxalic acid is a powerful rust treatment method, but it must be handled with care, similar to, but not quite as dangerous as, caustic soda.

All these treatments will work with varying degrees of results, according to the amount of corrosion, the amount of scale, and the overall condition of the cooling system.
Scale is by far the most undesirable product in the cooling system, and is difficult to remove. Scale prevents heat transfer to the coolant, and is a primary cause of overheating.

The technique is to drain and flush the cooling system with clean water and hose out as much gunk as possible.
Then fill with your chosen cleaner (picked according to your radiator condition).
If the radiator is in poor shape, with white spots all through the fin joins in the core, then you don't want to use a harsh cleaner, as it will make the radiator leak at those white spots (which is indicative of severe radiator corrosion).

Once you've thoroughly flushed the system, fill with clean water and add your cleaner. Leave for overnight or even longer, and check regularly on the cleaning result by peering into the filler neck.
Running the engine to operating temperature will speed up all the cleaners activity, and reduce the time needed for cleaning.
Idling the engine is the fastest way to bring an engine up to operating temperature .. but don't idle for a lengthy time in a closed building, or you'll gas yourself.

Once the cleaner appears to have had satisfactory results, drain the solution, and flush with clean water until the water runs clear.
Refill with a good commercial rust-inhibiting pre-mixed coolant, that contains a glycol base, and keep this coolant topped up with a similar mixture.
Never add plain water to any cooling system, it dilutes your inhibitor.

Cheers - Ron.

JBran - Depending on how bad your system is, you can use any one of a dozen different cleaners. You need something that will clean up corrosion, without being too harsh.
A cleaner that is too harsh will make holes develop in the thinner material in the cooling system, such as the radiator.

You can buy commercial cooling system cleaners, which are generally quite mild. These cleaners are usually only used when cooling systems are not too rusty.

You can use a cupful of dishwasher powder, which is moderately alkaline. Many people prefer this simple treatment.
The dishwashing powder contains detergents that also helps release fine clay particles that are often associated with cooling system degradation.

You can use a cupful of caustic soda, which is strongly alkaline. Great care must be taken when using caustic soda, and safety equipment such as gloves and eye protection is highly recommended, to protect against skin and eye damage in the case of spillage.
Be aware that caustic soda eats away alloy components fairly rapidly. You don't want caustic soda in contact with alloy parts for more than couple of hours.

You can use about a cupful and a half of Citric acid. Citric acid comes in granulated form, looks like sugar, is very safe to use (it's a common food additive for preservation and is used in "bath bombs").
Citric acid cleans up corrosion in a very admirable fashion, without damaging the softer metals that may be part of cooling systems and engines (alloy components and solder).

You can use a cupful of Oxalic acid (available as a cleaning agent in granulated form in 500g containers).
Oxalic acid is a powerful rust treatment method, but it must be handled with care, similar to, but not quite as dangerous as, caustic soda.

All these treatments will work with varying degrees of results, according to the amount of corrosion, the amount of scale, and the overall condition of the cooling system.
Scale is by far the most undesirable product in the cooling system, and is difficult to remove. Scale prevents heat transfer to the coolant, and is a primary cause of overheating.

The technique is to drain and flush the cooling system with clean water and hose out as much gunk as possible.
Then fill with your chosen cleaner (picked according to your radiator condition).
If the radiator is in poor shape, with white spots all through the fin joins in the core, then you don't want to use a harsh cleaner, as it will make the radiator leak at those white spots (which is indicative of severe radiator corrosion).

Once you've thoroughly flushed the system, fill with clean water and add your cleaner. Leave for overnight or even longer, and check regularly on the cleaning result by peering into the filler neck.
Running the engine to operating temperature will speed up all the cleaners activity, and reduce the time needed for cleaning.
Idling the engine is the fastest way to bring an engine up to operating temperature .. but don't idle for a lengthy time in a closed building, or you'll gas yourself.

Once the cleaner appears to have had satisfactory results, drain the solution, and flush with clean water until the water runs clear.
Refill with a good commercial rust-inhibiting pre-mixed coolant, that contains a glycol base, and keep this coolant topped up with a similar mixture.
Never add plain water to any cooling system, it dilutes your inhibitor.

Cheers - Ron.

Thanks Ron, hope this helps you too comtruck!

I was told ,If you use Caustic soda ,the flush with Bi carb Soda ,which is supposed to neutralize the Caustic .