Brake fluid question

[pjvargas]

1982 M35A2 bought from the government thru government liquidation.
Brake fluid in master cylinder low, plus leak at one of the rear wheel cylinders, so I need to fix wheel cylinder leak (possibly bleed) and top off fluid.
There is the usual MIL-B-46176 sticker on the underside of the master cylinder access door specifying the use of the Silicone Brake Fluid.
I've never added brake fluid to this truck and the brakes work OK.
When I stuck my finger in the master cylinder and pulled it out the fluid was a golden amber color.
Silicone brake fluid is colored purple.
DOT 3 and DOT 4 is colored clear to amber.
Mixing the two would not be the thing to do.
I know the military is supposed to be using the purple silicone brake fluid and I'm assuming that that is what SHOULD be in the system, but it seems like there is DOT 3 or 4 in the system.
Before disaster strikes what advice is there on verifying what I already have in the brake system?
Any advice is appreciated. Does it seem likely that someone in the military serviced this truck with DOT 3/4 rather than the silicone fluid?
Anyone run into this before? Any thoughts?

 

[Recovry4x4]

The BFS will turn amber/yellow. Extract a small amount and add some water. If they mix it will be DOT 3/4. If it clearly seperates it's BFS (DOT5).

 

[big1096]

Chances are it's DOT 5. Mine is and it's bright yellow. Here's a page describing how to test it...

http://www.steelsoldiers.com/safety/7031-brake-fluid-how-tell-kind-you-have-dot-3-dot-5-a.html

 

[pjvargas]

Thanks

Thank you both! I guess I'm kind of stunned that folks report that the silicone brake fluid which is supposed to be a purple color has actually turned an amber or yellow color on them over time (too hard to argue with facts and reality).
Your input is much appreciated. I'll try the referenced water test; sounds very logical.

 

[ODw/envy]

I'll bite. I picked up my truck last month. "no brakes" according to GL. I inspected, on recovery, and found a brand new out of the box MC and lines to the air-pack. Great, I thought! Checked inside to find beautiful purple nectar. Sweet, wright?

I went on to other things to prep the truck for the trip. I had almost everything the way I wanted, so I turned on the accessory and hit the red button. Wop, wop, GGGGEEEERRRR. Big smile we are in business.

When I pushed the pedal it went to the floor without any resistance. No surprise, I'm thinking they never finished bleeding it, right?. So I pumped the pedal a few times and jumped out to start bleeding (manually).

I opened the first bleeder, air. Pump, pump, fill, pump, pump fill. It seemed like a week and then to my horror milky yellow fluid started squirting out at me.

Already long story short, I had no option, I bled the lines until I saw purple in all of them and we left. We made the trip no problem and the pedal went from mediocre to perfect after 50 miles or so. 1200+ miles no problems so far.

Today I was playing with my M101A2 and found golden yellow fluid and it got me wondering "what is going on". I was beginning to think either I am crazy or someone is screwing with me. Thanks to the forum and the contributing members I may have my answer. I'll do the water test on them tomorrow.

I do have one question though; can silicone fluid, containing water, take on the appearance of saturated hydraulic fluid in the field? I have worked on tractors, in the field, that had similar looking fluid when hydraulic lines ruptured.

OD

 

[Rustygears]

Since you didn't originally fill the brake system and cannot determine that ALL the fluid in the system (MC, air pack, wheel cyls) is all pure DOT 5 and has had no water incursion, etc. I would strongly suggest purging and refilling with fresh DOT 5. There are reputable vendors of fresh Mil DOT 5 in gallon containers that are reasonably priced. If you buy enough DOT 5 to do the job at retail prices, you'll spend well over $100.

Since you have an A2 with a single circuit brake system, there's really no margin for error in the brake system. One common reason for wheel cylinder failure on A2s is due to water incursion. The fact that one failed suggests that others may be in a similar situation.

 

[PalmerBS]

Yeah you certainly don't want to lose brakes on one of these bad boys, i did backing off a hill once, and the only thing that stopped me was a telephone pole (that paid the price).

You can't be too careful w/ the brakes. I would purge and fill w/ DOT5 as well if there's any question. Only problem you'll run into is NAPA wanting $120 for a gallon of it...and the alternative is waiting for delivery of much cheaper fluid from someone on here.

 

[ODw/envy]

I actually got a "blem bottle" form an HD dealer in NV. The safety ring was missing form the cap but it was a brand new, unopened gallon. Normally, $135 plus, plus. I got it for $62.25 plus $7.50 for shipping. Ebay is great, sometimes.

OD

 

[PalmerBS]

I was able, after some searching, to find a guy w/ about 70 gallons of the military green can stuff...snagged them a $50 per with $10 shipping.

I felt like i won the freakin lottery!

 

[pjvargas]

Source for MIL-PRF-46176B Silicone Brake Fluid

IRIS Industries Iris Industries, Inc is on the Qualified Products List (Government qualified) for the MIL-PRF-46176B (was MIL-B-46176) silicone brake fluid used by the military. You can buy direct from them in Quart or Gallon sizes. If you buy from them you are guaranteed on getting the MIL-PRF-46176B fluid used and specified by the military.

 

[pjvargas]

MIL-PRF-46176B versus commercial DOT 5 brake fluid

The MIL-PRF-46176B fluid is slightly different from commercial DOT 5 silicone brake fluid as follows:
Excerpt from the MIL-PRF-46176B specification-
6.1 Intended use. The brake fluid covered by this specification is military unique due to the requirement that it perform at a minimum ambient temperature of –55°C, whereas commercial silicone-based brake fluids are rated at a minimum ambient temperature of –40°C. It is intended for use as an operational fluid and preservative fluid in automotive hydraulic brake systems at ambient temperatures ranging from 55°C to -55°C and fluid temperatures ranging from 205°C to -55°C.​

 

[Truckoholic]

This has allready been discussed, but figured I'd just confirm by pasting the following that I found in an Ebay Auction for the stuff.

***So how do you tell which fluid is which? Go by the color, if you can. BFS is purple or blue in color, though the dye that gives it the color can break down. Then the fluid becomes brown or amber.

There's no cause for alarm if the color varies--the BFS is still good. But if the color is not purple or blue, you can't tell what kind of fluid is in your brake system.

BFS + Unknown Fluid

Try mixing a few tablespoons of the unknown fluid with a little BFS. If the two mix, the unknown fluid is BFS, too. But if the two fluids separate into layers, the unknown stuff is DOT 3 or 4. Your vehicle needs to have the brake fluid changed.

Unknown Fluid + Water

Put some of the unknown fluid in a jar with a little water and shake it. BFS does not mix with water, and you'll see distinct layers. DOT 3 and 4 fluids, on the other hand, do mix with water and remain mixed. You won't see separate layers.

 

[PalmerBS]

Still a good write up

 

[pjvargas]

Color

Kind og bogus also that the Silicone brake fluid is supposed to be the color Purple to help identify it, but that it can break down to a yellow or amber color that would lead you to think that it might be another fluid (DOT 3 or 4).
Doesn't seem very foolproof.
Just my thought but the specification should specify that the color not break down over time?????

 

[Jake0147]

It's not really bogus. BFS is not DOT 5 brake fluid. MSDS sheets can confirm this. They are close, but BFS does not fit the bill and could never be sold as DOT 5. The purple dye is for federal safety standards, so Joe Public doesn't mis-identify it and add it to the wrong system. The army is all about "one fluid for everything", thus mix-ups are not (theoretically) an issue. Their fluids come to their spec from the lowest bidder, and do not need the added expense of a dye to make them compliant and legal for street use. (OK, I don't think it's about "use", more like "legally sold", or "legally represented as brake fluid"). Something along those lines.

As for the dye fading, since there is NO manufacturer that recommends or allows the indroduction of anything but new fluid from a sealed container, that is a non issue.

 

[pjvargas]

Here is a list of the current manufacturers/vendors on the Qualified Products List (QPL-46176) for MIL-PRF-46176, Brake Fluid, Silicone, Automotive, All-Weather, Operational and Preservative.

Manufacturer Designation AJ-331
Source Name
A-J CHEMICAL, LUBRICANTS & EQUIPMENT COMPANY
A J CHEMICAL EQUIPMENT
915 PLEASANT ST
RICHMOND, VA 23223-6109

Manufacturer Designation ARPOLUBE 46176
Source Name
CHEMICAL SPECIALISTS AND DEVELOPMENT, INC.
C S D
9733 MEADOR RD
CONROE, TX 77303-2335

Manufacturer Designation CAYLEE-420
Source Name
C&F WORLD INNOVATIONS
202 BAKERS BASIN RD
LAWRENCEVILLE, NJ 08648-3308

Manufacturer Designation CLEARCO DOT-5 SILICONE BRAKE FLUID
Source Name
CLEARCO PRODUCTS COMPANY, INC.
3430 G PROGRESS DR
BENSALEM, PA 19020-5812

Manufacturer Designation IRIS-911, SILICONE BRAKE FLUID
Source Name
IRIS INDUSTRIES, INC.
28 INDUSTRIAL DR C
TRENTON, NJ 08619-3245


I know IRIS INDUSTRIES will sell direct to customers. If you are near one of the other vendors it may be convenient to get from them direct.

 

[Welder1]

I got an email from Iris Industries the current pricing on 1 gallon of silicone brake fluid is $27.69 plus shipping. That's as of 2/11/2017.

 

[ageregunner]

This has been an excellent thread. Thanks to all that contributed.

 

[rustystud]

I got an email from Iris Industries the current pricing on 1 gallon of silicone brake fluid is $27.69 plus shipping. That's as of 2/11/2017.

WOW ! That has gone down considerably since I last bought a couple of gallons from them.

 

[18operator]

That sounds like a really good price. I paid $20 for a quart from a mom and pop auto parts store, and had to wipe the dust off the bottle!