DIY Network

Automotive Fluids -- Changing Engine Coolant From "Car Care Workshop" episode DCC-105

Media For a 3D-animation look at how coolant flows through the engine and cooling system of a car, watch this video.

One of the most commonly neglected maintenance procedures is changing coolant, or antifreeze. On average, for every hour an engine runs, about 7,500 gallons of coolant circulate through its cooling system. Coolant usually contains ethylene glycol, along with rust inhibitors. The life span of these chemicals is about two years, so about every 24,000 miles a complete coolant flush and change is recommended. (Check your owner's manual and product information for your coolant. Some products have a much longer life span.) Otherwise rust and impurities may build up and clog the system, or the antifreeze may become ineffective. If you ignore the coolant, a severe freeze could crack your engine block.

Changing the coolant doesn't mean simply draining the radiator and refilling it. Doing so would leave at least half the coolant (the portion in the other components of the cooling system) still in the engine, along with half the rust and impurities. The cooling system includes a number of components other than the radiator: the water pump, radiator hoses, channels within the engine block, heater hoses and the heater core. A complete coolant change means back-flushing the entire system, then adding new coolant.

advertisement

	Figure A
	Figure B
	Figure C
	Figure D

Caution: Antifreeze is toxic and must be disposed of properly at a fluid-recycling center. Keep it out of the reach of pets and children, and avoid skin contact. Also avoid spilling it on painted finishes.

Note: It's dangerous to open the radiator while the engine is hot. Make sure the engine has cooled completely before you begin.

Materials:

coolant
cooling-system back-flush kit (includes fittings and clamps)
screwdriver
nut-driver or socket wrench
wrench
utility knife
garden hose
catch basin
bucket

1. With the engine cool, open the recovery-tank cap and the radiator cap to relieve any pressure. An alternative method is disconnecting the top radiator hose.

2. Locate the radiator drain and the stopcock at the bottom of the radiator. Place a catch basin beneath it, open the valve, and drain the fluid (figure A). Some radiator drains will accommodate a hose so you can direct the flow of the fluid.

3. The easiest way to flush the system is to install a back-flush kit (figure B). Follow the kit's installation instructions. The T-fitting installs in the heater-inlet hose that runs from the firewall to the top of the engine. Install it in a relatively straight section of the hose. First, cut the hose (figure C), and slip a clamp over each cut end. Install the T-fitting that fits your hose most snugly. Tighten the hose clamps with a screwdriver (figure D).

4. Connect the back-flow prevention coupling to the T-fitting (figure E), then connect the garden hose (figure F).

5. With the radiator cap removed and the radiator drain closed, insert the plastic diverter into the neck of the radiator. You may want to attach a piece of hose or tubing to the diverter so you can direct the spent fluid into a bucket.

Figure E

Figure F

Page  1 | 2