Thursday, October 21, 2004 - 04:46 am, by: Peter (Admin)
Your brake fluid absorbs moisture and deteriorates over time. It should be replaced every 2 years maximum, more often if you do track days. Fortunately to flush out the old brake fluid and replace it with new brake fluid is a very simple job.
You need a 10mm spanner, approx. 1/2 metre of 5mm (internal diameter) clear hose, a small piece of gladwrap, a rubber band, and a collection bottle for the old fluid. If you have something to suck the old fluid from the reservoir, eg a turkey baster or something home made, so much the better. You also need a litre of decent brake fluid, I buy 4 litre bottles as I flush my brakes often. A small (home made) funnel is handy and a few old rags to wipe your mitts on.
Before starting, with the ignition OFF, press the brake pedal a few times to exhaust the booster. You should notice that with the first 2-3 pushes, the pedal gets firmer and is higher from the floor. This indicates the booster is sealed properly.
If you can suck the old fluid from the reservoir, now is a good time to do it, then top it up with the new brake fluid - using the funnel if you have one. Brake fluid absorbs moisture from the air, so put the lid back on straight away.
Wrap the gladwrap around one end of the tubing and hold in place with the rubber band to make a simple one-way valve. This makeshift valve will let the fluid out, then collapse and stop the fluid being sucked back up again. This saves you from the traditional method of needing two people to do the job and trying to stay coordinated.
Start with the wheel farthest from the reservoir, rear passenger wheel for right hand drive cars. Jack the car and remove the wheel. Pop off the dust cap on the bleeder valve, then using the 10mm spanner just crack the bleeder valve open and shut again lightly. Fit the open end of the tube to the bleeder and place the other end into your collection bottle, have the hose go up higher than the bleeder to stop any air bubbles going back into the brake system. Open the bleeder maybe 1/4 turn.
Start pumping the brake pedal, old dirty fluid should start passing down the tube into your bottle. After about 10 presses of the pedal, check the fluid level in the reservoir and top up as necessary. Make sure the reservoir does not get empty, it will suck air into the system which can be very hard to remove if you have ABS.
Keep going until you see nice clean fluid coming out the tube. Tighten up the bleeder valve but don’t overdo it. Check the pedal feel, it should feel firm.
Replace your wheel, top up the reservoir and then start on the next wheel farthest from the reservoir.
When all brakes are done, dispose of the old fluid properly, it’s should not be tipped down the drain. Start the car and check the brakes feel to be working properly, then go for a gentle drive to test that the brakes feel and work OK.
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