I have a more solid pedal with the DOT 5 than I ever had with DOT 3 and that's even when I was pressure bleeding the car in years past.

Brakes are awesome now!!!!

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Own a 1979 300sd. Would replacing the front/rear calipers and replacing the Master Cylinder be sufficient when switching over to DOT 5 or should all the hoses be replaced also? Just wondering. Which brake components should be replaced prior to switching to DOT 5?

If the flexible lines are old / original I would replace them on principal...

Don't believe all the horror stories you read. Some strange warnings are even on bottles of DOT 5. There is no problem mixing DOT 5 and glycol, and silicone will not adversely affect your seals or hoses. Indeed, it is more benign than glycol. The only problem is that leaving drops of glycol are places where rust can start.

I would disconnect the MC tubes and eject all the glycol you can (catch it, don't let it drip on your paint!). I would run a little fresh glycol thru the MC, since you don't want any left with dissolved water. "Bench-bleed the MC w/ DOT 5 (I do it on the car). Reconnect the tubes and bleed all the wheels. The DOT 5 should displace almost all the glycol. You should see clear blue fluid eventually. Don't fret when the DOT5 fluid in your reservoir turns yellow later. That is not rust, just aging of the blue dye. Even better is to blow out all the glycol with air, then alcohol, and change or rebuild the calipers and wheel cylinders, but not required. Of course, if your hoses are cracked or old, replace those and maybe do a better flushing.

For more info on DOT 5, there is a detailed writeup by an anal engineer. I don't have the link with me, but am sure you can find it. He had Triumph cars as I recall.

What type of brake bleeding is recommended? Vacuum at bleeders, speed bleeders or use my Motive brake bleeder tank with pump and pressure gauge.

I gravity bleed mine initially, to move the fresh fluid through the system, then finish by pushing the caliper pistons back with the bleeders open to purge the old fluid from the calipers....

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

I use a hand pump with a long air hose and a brake fluid cap with a air nipple. First almost remove the brake fluid from the reservoir. Pour in fresh fluid, put on cap with nipple, attach air hose, go to the bleed screw at the brake calipher, attach hose that goes into a old bottle, pump with the hand pump so that you have about 1 bar pressure, open bleed screw until fresh fluid emerges. Pump if the pressure drops too much. After every brake calipher or clutch cylinder (manual transmission), refill reservoir.

the only method for me on a Benz is a 2 man bleed followed by a 2x4 over night against the brake pedal

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Sigmoidoscope designer?

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CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

What DOT 5 silicone brake fluid is the best product currently available in 2017?

Thanks !

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

You can buy it in some auto parts stores or online.

I picked up surplus military, a gallon of it. It's purple.

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Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

Since somebody pulled this thread up, I'll keep bothering people and add more experience. I also bought 1 gal off ebay, maybe twice, usually $75/gal. Search for the MIL number. I think the military stopped using it because of cost and availability, though the later is a chicken & egg situation. After mil-surplus is gone, you might have to buy it in pt or qt bottles, as many current motorcycles use it.

Don't be alarmed if you drain some fluid later and find it is amber. That is not rust. The blue dye fades over time and light yellow is apparently the fluid's natural color.

I since put silicone in an ABS vehicle (96 Voyager minivan). I was doing brake work, needed to flush, and had a gal so figured why not. I just drew the reservoir down and slowly filled silicone as I bled. In all prior cars I swapped only during a total rebuild, blowing the brake tubes thru w/ ethanol and such. In short order, I saw a very distinct change from the slightly rusty glycol fluid to the blue silicone. I kept going to insure almost pure silicone. I haven't tried in a wet parking lot, but did feel the ABS kick-in once when I had to brake hard over a paint stripe on a wet road and felt the normal pedal pulsing. Silicone fluid sure won't make the ABS actuate sooner since that is controlled by the sensors at each wheel.

As others, I haven't felt any spongier pedal. No difference other than I don't have to worry about rust in the system. Those who fear dripping water into their brake reservoir have a valid concern, and they should also fear dripping water into their power steering reservoir and transmission fill tube. They also probably shouldn't be allowed under the hood of a car. If you still have cracked rubber "test caps" on your brake reservoir, change them (cheap at Pelican). I put vinyl caps on mine (shipping protectors for hydraulic fittings). If you spray wash your engine bay, first wrap the brake and. p.s. reservoirs w/ a plastic bag.

Link to the anal engineer's evaluation of silicone fluid: Selecting Brake Fluid

Attached military training poster from when they switched exclusively to BFS. Seems they might have switched back to glycol.

Attached Files

Military poster on DOT 5.pdf (729.0 KB, 204 views)

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I didn't bother reading the earlier part of the thread, but I will tell you this nonetheless.

I have a lot of experience with using DOT5 fluid. I've used it in many different race cars, where it is an excellent choice. It provides a hard pedal and exceptionally high boiling point. (Says captain obvious.)

For street use, there are caveats. If you are building a kit car or completely replacing every hydraulic component, then sure - use it. Except the viscosity may have a small impact on ABS performance. Yes, the pedal will still pulsate and the wheel lockup will still be controlled, but perhaps not quite as precisely due to some minuscule lag from the higher viscosity creating some hydrodynamic resistance.

For street car use, problems arise from people that do not thoroughly flush out the old fluid or use alcohol to flush the system. (Most) alcohol contains water. Old contaminated fluid will still have moisture in it, and alcohol... well, that's obvious. If/when the moisture condenses out of the old fluid (freezing temperatures?) or water congregates from the alcohol flush, and collects at the low points of the system, that's where problems begin.

Brake fluid being hygroscopic does not allow pure liquid water to exist in the system; instead it is widely distributed. Now I want you to imagine even one drop of liquid water sitting at the bottom of a caliper's bore. The corrosion is magnified at that one little point. You can kiss that caliper goodbye.

Worst case scenario: Say that the drop of water is right adjacent to the piston seal, slowly rotting away the metal. The corrosion will grow and extend further around the circumference of the seal. The rust will continue to hold a liquid seal for a while, but it's weak at that area. So what happens one day when some texting, nose-picking Bozo makes a left turn in front of you and you try to push the brake pedal through the floor... and the lip of the seal lets go at the edge... whoosh, there goes the fluid.

Same principle applies to the low points of steel brake lines. Sure, eventually the corrosion will eat through and drip, but what about right before it starts leaking? That's when the metal is weak and can potentially burst at high pressures induced by panic braking.

So you say you'll flush the system every two years anyways? Not gonna help. The liquid water will not be pushed out of low points because the fluid velocity isn't high enough to displace the water.

Now imagine the liability (legal or moral) that comes from selling a car that was improperly converted to DOT5 and someone gets hurt.

OK - this is much longer than I originally anticipated... so I've got to stop now.

__________________
Current rolling stock:
2001 E55 183,000+ Newest member of the fleet.
2002 E320 83,000 - The "cream-puff"!
1992 500E 217,000+
1995 E300D 412,000+
1998 E300D 155,000+
2001 E320 227,000+
2001 E320 Wagon, 177,000+

Prior MBZ’s:
1952 220 Cab A
1966 300SE
1971 280SE
1973 350SLC (euro)
1980 450SLC
1980 450SLC (#2)
1978 450SLC 5.0
1984 300D ~243,000 & fondly remembered
1993 500E - sorely missed.
1975 VW Scirocco w/ slightly de-tuned Super-Vee engine - Sold after 30+ years.

Interesting points Bill and Running.

So, can silicone dot 5 simply replace Dot 4 as you did in the Dodge minivan via basic flushing gravity techniques and several ounces of dot 5 or is a 'power flush' recommended/needed as some Midas brake shops may offer?
Is the possible 'residual moisture' issue that critical on average ?


Thanks martureo for the images !

update: thanks Bill, I just read the engineer's thread. It answered my questions. (Also I used to own a 1967 MGB back in the 1980's and I just remembered that I had it changed to Dot 5 Silicone via Midas brake shop with my fluid bought from Moss Motors around 1982.)

"Experienced Suggestions: This set of suggestions came from people that had actually done the job. Many reported changing fluid after rebuilding the entire system and some blew out the lines before filling with silicone fluid. Others merely added the DOT5 at the master cylinder and then bled the system until the purple fluid flowed from each bleed nipple. In every case these folks reported excellent results. Some had over ten years service on the vehicles with no failures reported. Several of the vehicles were the daily driver later model cars and one case involved a motor home that the fluid had been switched more than ten years previously.
Thoughtful Suggestions: This group of suggestions came from folks that had great concern that some contaminated glycol fluid might be left in the system and suggested that every effort be extended to get out all the glycol-based fluid. There may be a problem in the wheel cylinders and calipers because the silicone fluid floats on the top and next to the bleed nipple and it is possible for the DOT5 to flow freely from the bleed nipple while there is still a pocket, possibly large pocket of the glycol fluid remaining in the lower part of the cylinder/caliper. None of the folks in this group said they had experienced any trouble with switching fluid (if they actually switched the fluid) and none reported actually finding pockets of contaminated glycol fluid in the wheel cylinders/calipers either before or after switching to silicone fluid.

Randall Young contributed: I have found what I believe were pockets of glycol fluid when disassembling brakes that were converted only by bleeding. It certainly looks (and is) a mess, (almost like tar) but it doesn't seem to hurt anything. Might cause problems if it accumulated in the valves of an ABS system for instance, but none of my cars have ABS.

Off The Wall Suggestions: These folks made dire predictions if silicone fluid were used in a TR at all, or if the fluid was switched without taking drastic steps. One group said that the seals in the TRs were natural rubber and the swelling agents in the silicone fluid didn't work properly with rubber seals. No source of the data was cited nor was any actual experience and failures cited. We know from Browning's report that the silicone fluid produced as early as 1974 was compatible with all types of rubber used in brake systems. I don't know the type of seals used in TR250s/TR6s to which this is addressed but I expect all replacement hoses and seals meet or exceed DOT specifications and thus will work just fine with DOT5 fluid.

The other group of "off the wall" suggestions said to replace all rubber components (hoses & seals) and flush the system with alcohol. Again, no basis were made for this suggestion nor did any of these folks say they actually did this nor did they present any data to show something bad would happen if it wasn't done. I think the alcohol was to absorb and remove any moisture from the system, which of course is a good ideal since the moisture won't mix with the DOT5 and you don't want water lying around the system. However, if there were glycol fluid in the system previously, it would have sucked up any water. [Unfortunately, if you flush with alcohol, you're then stuck with alcohol residue that is probably worst than water.] Replacing the seals and hoses seems to suggest that the glycol fluid somehow damaged the seals and hose components such that they will quickly fail if DOT5 fluid is introduced into the system. I've seen seal deterioration from glycol-based fluids --- that's why the seals fail and the fluid leaks and ruins the paint. However, I assumed that was normal deterioration. One basis for this suggestion might be that DOT5 fluid will allow a higher performance from the brake system than the glycol-based fluids and if the seals and hoses are old, they should be replaced before the brake system is subjected to the greater stress possible with the silicone based fluid. "

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD