2003 4Runner Brake system flush by Bulldog

It is recommended to flush the brake system every 2 years or so to avoid moisture absorption and premature damage to seals and components. Basically suggested to have the brake system last much longer and work better in the long run. I had my system flushed by the dealer last year in 2005, at the 2 year mark. So it was not really necessary to do it this year, but I was installing stainless steel brake lines so I decided why not flush the brake system while I’m at it.

I decided to use synthetic brake fluid as it is supposed to have lower moisture absorption and also exceeds both DOT3 & 4 specifications. I used Valvoline synthetic fluid as it was easily available and looked like a pretty good product. Castrol also makes a good product, but it was not available locally. It takes more than 1 qt of brake fluid, so I just got 2 to be safe. the 4Runner certainly has a big reservoir. More info on the fluid can be found here at the Valvoline site.

To make the operation easier and quicker I got a vacuum bleeder from Motive Products. It is actually a multipurpose vacuum extractor, which can be used for engine oil, diffs, etc. It comes with a tube for engine oil extraction and other oils, it also comes with an additional tube that slips onto the oil extraction one to extract brake fluid and also slips onto the bleeding nipples on the brake calipers. It is pricey at around $60, but other products are also available. More info can be found at their site. Below is a pic of mine, the gauge is a nice touch to show the vacuum in the unit.

The bleeder has a little clamp on the main vacuum line which has to be closed before use. Then just use the pump handle and pump till about a 10-12psi vacuum. Then extract as much of the old fluid as possible from the reservoir using the extractor. Then add the fresh fluid in the reservoir. Please muke sure the tube used for extraction is not contaminated by any fluid especially oil. New ones can be bought at your local hardware store.

Now it is time to extract the fluid from the calipers. I started at the right rear first, then the right rear followed by right front and left front. Simply remove the rubber cap from the nipple on the caliper. Wipe nipple clean and slip extractor tube over it. Make sure you have 12 psi or so vacuum, then simply use a 10mm wrench and open the nipple till the fluid and air comes out. As this unit is extracting it will not create a solid line of fluid as with pressure units on the reservoir. Air slipping by the threads in the nipple will always mix with the fluid extracted, so don’t worry about it. Just let the unit run till you can see the fresh fluid coming out in the vacuum tube. In my case the old fluid was so fresh I just had to let it run for a while. Keep adding fresh fluid to the reservoir as you go along, make sure it never goes below the MIN line. Add a few pumps to the extractor from time to time as well. The first nipple takes the longest as it has to work the longest line and also the rest of the old fluid out of the reservoir. Once done simply close the nipple, close vacuum line with clamp, remove tube, wipe the nipple clean and all areas that might have brake fluid on it, put cap back. Do the rest of the nipples in the same way.

Front caliper and nipple                                                                             Rear caliper and nipple

Put back everything you removed and you are done. You can do this without jacking up the 4Runner or removing the wheels, but removing the wheels does make it easier.