the Mechanics of changing the brake fluid

[hands_aus]

It seems strange that in 13 years of owning my 250sl I have never changed the brake fluid myself.
So I am going to include it as part of my summer maintenance schedule.

As part of a larger project on the car in November 2006, I had the brake calipers rebuilt and replaced the MC at the same time.
Since then the brake fluid has been changed every 12 months as part of other projects including replacing all the brake hoses in June 2014.

I watched a video on Utube about using a one-man pressure bleeder but the bleed nipple was accessed through the spoked wheel rim..... nothing like the Pagoda wheel rim.
For this project I made a one-man garden sprayer pressure bleed unit to use.

My Question
As the brake bleed nipple is very close to the wheel rim and combined with the fact that there is very little room under the car to access the bleed nipple, do I need to remove each wheel when I want to bleed the brakes
OR do I need a special spanner to loosen/tighten the nipple
OR do I need to raise the car at each corner one at a time.

thanks

[ctaylor738]

I have always put the car up on jackstands and removed the wheels.   If the fluid is in bad condition, I suction as much fluid as possible out of the reservoir.

Then you bleed the brakes starting the furthest away from the master cylinder.  So on a LHD car, the order is RR, LR, RF, and LF.

The bleeder nipples can be 8, 9, or 10 mm.  You can use a flare wrench or a deep-well six-point socket to break them loose.  Once they have been loosened a bit, I put a box-end wrench on the nipple in a position where I can get a 180 swing to open the bleeder.  Then I attach the bleeder hose, open the bleeder.  I use a clear plastic hose for the bleeder, and when the fluid runs clear and free of air bubbles, I close the bleeder.

When finished, I use a small hand pump to lower the fluid in the reservoir to the correct level.

[hands_aus]

Hey Chuck,
Thanks for the reply.
I have some jack stands and there are probably some old box spanners from my fathers estate somewhere under the house (on stumps off the ground).

The brake fluid is only 12 months old and about 2 years ago I had the bleeder valves replaced plus they all have the rubber caps in place so they should be ok.

I will take my time.
Hopefully I won't have any further questions.
cheers

[Benz Dr.]

I use anti-seize on the bleeder valve after I remove it. If it's very tight there's going to be rust in the threads.

Something to consider: when removing the bleeder valve, only use light taps against the side of your wrench to break the valve free. Constant pressure is much more likely to snap it off and ruin a good caliper. If the valve is really tight you might have some luck with heat but it's not a certain thing.

[jameshoward]

I'd say changing the fluid every 12 months is mighty excessive and a waste of money. Modern fluids are designed to cope with considerably more than the pagoda driver throws at them. For those with manuals, don't forget the clutch fluid.

If you haven't done it yourself before, it's worth considering just how corrosive it is - any spillages must be wiped up immediately. Also, when you've got your new fluid, let it stand for 24h in the can to allow the air to bubble out before starting. And if using the pedal to bleed (though you say you aren't) it's worth putting a block of wood under the clutch pedal on a manual to prevent excessive travel.

Lots of good posts on the site about bleeding brakes, etc.

[Jonny B]

I would agree with James on the timing. I use my car about 1500 miles (give or take) and do the brake fluid flush every two years.

I had not heard about the 24 hour settle time, good idea.

Also any unused brake fluid won't be stable (it will pick up water), if you don't use it all, dispose of the remainder at the local hazardous waste disposal site.

[Cees Klumper]

All maintenance schedules I've recently seen (and used, for cars and motorcycles) consistently stipulate a 2 year replacement interval for brake fluid. I use a Mytivac vacuum system to replace my break fluids, it's kind of fun and rewarding to do.

[Benz Dr.]

Apples and oranges. Brake fluid hasn't changed that much but braking design has. The braking system on a 230SL isn't very air tight and the brake fluid in the system will  absorb water with resulting rust in the rear cylinders. Much of this depends on where you live and how much and how often you drive your car.

Living in the mid west near the great lakes, there's always lots of humidity in the air. Everything will rust regardless of how it's stored. Heated dry environments will be very good and outside storage won't be very good at all.   

[Jonny B]

Dan,

Excellent point about the climate. I have become a bit jaded being out here in SoCal.

[66andBlue]

Apples and oranges. Brake fluid hasn't changed that much but braking design has.  ......

Hi Dan,
chemists (and horticulturists) will most likely disagree with you:
" Glycol-ether (DOT 3, 4, and 5.1) brake fluids are hygroscopic (water absorbing), which means they absorb moisture from the atmosphere under normal humidity levels. Non-hygroscopic fluids (e.g. silicone/DOT 5 and mineral oil based formulations), are hydrophobic, and can maintain an acceptable boiling point over the fluid's service life.
Silicon based fluid is more compressible than glycol based fluid, leading to spongy feeling brakes. [3] It can potentially suffer phase separation/water pooling and freezing/boiling in the system over time - the main reason single phase hygroscopic fluids are used."
https://en.wikipedia.org/wiki/Brake_fluid

[wwheeler]

Might consider this for bleeding. I have one and is fantastic and very clean. I don't put extra fluid in the tank because I do not want to clean it out later. Instead I bleed off the pressure at the master cylinder cap and simply refill the reservoir. 2 or 3 refills and the entire system is bled. Not a drop spilled.

http://www.motiveproducts.com/

I find the vacuum systems draw air from the bleeder valve threads. This makes it difficult to know if air is still in the line or if it is coming from the threads. Yes, you can put a grease on the threads to stop the air, but that is messy to remove the valve.

[Benz Dr.]

Hi Dan,
chemists (and horticulturists) will most likely disagree with you:
" Glycol-ether (DOT 3, 4, and 5.1) brake fluids are hygroscopic (water absorbing), which means they absorb moisture from the atmosphere under normal humidity levels. Non-hygroscopic fluids (e.g. silicone/DOT 5 and mineral oil based formulations), are hydrophobic, and can maintain an acceptable boiling point over the fluid's service life.
Silicon based fluid is more compressible than glycol based fluid, leading to spongy feeling brakes. [3] It can potentially suffer phase separation/water pooling and freezing/boiling in the system over time - the main reason single phase hygroscopic fluids are used."
https://en.wikipedia.org/wiki/Brake_fluid

Ummmmmm.........OK. What part do you believe I don't understand? 

[ctaylor738]

The Motive bleeder works really well, but I suggest you replace the plastic hose with good quality reinforced rubber and put hose clamps on both ends.  I was bleeding away one day and noticed a spray of fluid going across the garage from a break in the hose.

[Jack Jones]

I use an electric vacuum pump and bleed the entire vehicle and works extremely well even with ABS systems. I use this method since I generally work alone and it eliminates working the master cylinder out of its normal operating range. Also, make a point of always replacing the rubber caps on the bleeder screws when completing the process as it prevents water from entering the screw and seizing in place.

[rutger kohler]

Hi, could Chuck (or anyone elase) tell me how to suction brake fluid out of the brake reservoir plse?  Santa is bringing me a new brake reservoir and I want to suction brake fluid out bof the brake reeservoir without breaking the lines. I had a look but there appears to be a neoprene splitter under the brake reservoir filler cap.  Does this pull out?

[Mike K]

Hi, could Chuck (or anyone elase) tell me how to suction brake fluid out of the brake reservoir plse?  Santa is bringing me a new brake reservoir and I want to suction brake fluid out bof the brake reeservoir without breaking the lines. I had a look but there appears to be a neoprene splitter under the brake reservoir filler cap.  Does this pull out?

Yes the splitter pulls out. I use a large syringe to suction the brake fluid out of the reservoir, others use a turkey baster.

I purchased a Sealey VS820 Brake Bleeder, a really useful piece of kit for bleeding the brakes.
https://www.youtube.com/watch?v=BucnEEe-QEo

Best,

Mike

[rutger kohler]

Hi Mike, thanks for that. Will use a syringe in the changeover now.
cheers

Rodger K

[ctaylor738]

I bought a couple of these pumps.  I use one for brake fluid and one for other fluids like gear oil.  The dual-size cap feature is handy.

http://shop.advanceautoparts.com/p/performance-tools-fluid-oil-pump-w1139/9016678-P?searchTerm=fluid+pump