Monday, July 25, 2011


Introduction: The radiator is an essential part of your LD's chassis and it's a component that is easy to overlook. It's generally recommended that one flush and change the coolant every 2-3 years - check your owner's manual for specifics. If one is at all unsure of the necessary equipment or the step-by-step procedures of a cooling system flush, there are many "how-to" descriptions and videos which outline the process. Check the owner's manual (or consult with with an engine manufacturer's service tech) to avoid any problems with a particular engine's requirements. (It is generally suggested that you use the coolant recommended by the manufacturer.)

The term 'flush' does have multiple meanings. There is the simple drain and fill, chemical flushing and "power flushing" (done at a shop).

Use *distilled water* for the coolant refill mix.

Caution: Make sure that there's a safe, "approved" place to dispose of the drained coolant and and "flush" fluids; some communities have oil and fluid pick-up and recycling, but many don't.

Caution: Be sure to mop up, then flush away any residue, any spills of coolant really well; animals like the sweet taste of "antifreeze" (ethylene glycol), and the stuff is extremely poisonous to them.

How to Flush the Radiator

If the radiator fluid appears to relatively clean, draining, refilling once with tap water, running the engine for 15 minutes or so, draining again and then a refill with the anti-freeze mix may be all you need.

If the fluid is dirty, you should follow a more involved method:

First, install a Prestone flush kit in the proper heater hose.

The kit permits a garden hose to be hooked up to the cooling system and pushes water in the opposite direction than it normally flows when the engine is running. This helps push out debris from the block, radiator and heater core.

Next, drain the cooling system, fill it with water and use a commercial radiator chemical flush. The engine is run for 15 minutes or so (follow the directions on the bottle).

The engine is then completely flushed, using the garden hose and flush kit, until the water runs clean. The radiator cap is left off to allow water to overflow. The kit has a fitting for the cap outlet that directs the water flow out of the engine bay. Once the water runs clean, stop flushing and drain the engine by pulling the lower radiator hose and block drains (if you can get to them). Reinstall the radiator hose and block plugs and refill with the proper mix of distilled water and coolant. Mix the coolant to the proper ratio and do not over do it. An overly rich mixture will not cool as well. Water itself transfers heat better but leads to rust and corrosion build up and does not properly lubricate the water pump seal.

If the cooling thermostat is old, this is the time to change it.

There are various brands and chemical compositions of coolants. The differences in chemical composition is primarily due to what metals are in contact with the coolant. The metals used have changed through the years and so have the coolants. Using the right type helps prevent corrosion and rust. Your owners manual will indicate the recommended type.

One problem encountered on many vehicles, is not being able to completely drain the cooling system. When trying to fill the system with pre-mixed coolant, you may not be able to get to get it all in. This causes the engine to run on a less than specified amount of coolant and too much water. When filling a cooling system, first look up the capacity of the cooling system, in the owner's manual. You can then calculate the proper amount of concentrated coolant and pour it in. The engine is then topped off using distilled water. This ensures the proper amount of coolant.

In the newer Ford V10s, Zerex G-05 is a recommended coolant.

Radiator caps wear out and need periodic replacement. Always replace with the same type, making sure the pressure rating, printed on the cap, is correct.

Here are instructions for a little simpler D-I-Y method of cleaning/flushing your radiator.

1 - Drain the car's entire cooling system. If you have antifreeze in it, dispose of the fluid properly. Refill the radiator about half way full. Pour in a gallon of white distilled vinegar. Fill the radiator the rest of the way up.

2 - Close the system with the radiator cap. Start the car and let it run until the temperature gauge begins to rise, then shut it off. Let the car sit for several hours or overnight.

3 - Drain the water system by removing the bottom hose or by opening the drain valve on the car's radiator. Flush the radiator out with a water hose as it drains. The vinegar is environmentally safe so you don't have to be too cautious, but you might want to catch the deposits and build up of minerals and lime that will be flowing out.

As mentioned before, dispose of the old coolant properly.


Some folks install a " Fail Safe" Thermostat of the temperature required or recommended for that specific vehicle. Fail Safe means it will never close shut and cause your vehicle to overheat if the thermostat goes bad. It will automatically go to the open position should it ever fail.

Others feel that today's OEM thermostats are robust mechanisms that do not fail when the coolant overheats unless the engine is so overheated that the whole engine is destroyed. Now, do note that if the engine has overheated due to the coolant leaking out, the most common reason for overheating, due to say a blown radiator hose, neither thermostats will be of any help since there will be nothing left to flow.

If the engine ever overheats, even if the engine is not damaged, the 'Fail Safe' thermostat will be permanently locked open and will require the thermostat to be replaced. In the same situation, the conventional thermostat will continue operating in its normal manner.

Running an engine with the thermostat permanently fully opened will delay normal warmup and, in cold weather, will keep the engine from reaching its normal temperature. This opens up a whole new can of worms. Modern engines need to be hot to operate correctly, run cleanly, get the mileage they were designed for and to prevent the buildup of sludge in the engine- all very bad things.

Contributors: Garry Foster, Joan Taylor, Neal Schlee, Steve, Larry Wade, Ed

25 Jul 2011

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