No brake fluid = HOLY $#@!.... DOT 5 or DOT 3

[MuddWeiser]

So today I accidently discovered just how heavy our CUCVs really are - the scary way! (and comparativley speaking they aren't that heavy - but when you don't have brakes, they will roll down a hill REALLLLLLY FAST!)

I was cruising down the hill and pedal went to the floor! Managed to stop once the road flattened out; had a look and front chamber of brake cylinder fluid tank was EMPTY! The smaller rear chamber was FULL.

Wondering where the fluid went as its not leaking at any of the brake lines or at the cylinder itself?


PROBLEM: I stopped at the next gas station and topped off with DOT 3 thinking surely that was the correct fluid... Then I get back home, hop on Steel Soldiers, and see that the CUCV Wiki calls for DOT 5!!!

DID I JUST CREATE A MAJOR HEADACHE FOR MYSELF? How do I know if I had DOT 3 or DOT 5 in there originally????

 

[oifvet]

The DOT 3 v. DOT 5 topic has gotten a lot of SS time.

Do NOT panic! They are compatible to the extent that you will have brake fluid in your system. That's most important.

Read the hashings here and decide. The purple stuff is specked (is that a word?) different for various qualities, but when you get down to the basics, they'll mix.

Later, you can push the 3 out and replace it with the high-dollar stuff.

Glad you were able to stop safely w/o injury to self or property. I've been there. In a deuce! Pedal to the metal, and NOT the "gas" pedal. Maybe even something stenciled.

If it had 5 in it, there should be a big yaller (yellow) sticker somewhere in or on the vehicle indicating the change mod. Usually near the master-cylinder or reservoir.

 

[wsucougarx]

grab some of your old brake fluid and put it in a small cup or container with a few drops of water. If you notice the water is not mixing with the brake fluid then it is silicone based (DOT 5) if you don't notice the water separating but blending in the brake fluid then it is DOT 3. Once mixed you want to wait at least 3-5 minutes or so before coming to a conclusion. If your entire system is depleted of brake fluid then it really doesn't matter. Just make sure you bleed everything out as to make sure you don't have the two brake fluids in there.

 

[wsucougarx]

Don't go off of stickers or the lack of stickers. My first deuce didn't have anything to show either way. You need to do the water test to confirm or you will have that headache after all.

 

[MuddWeiser]

grab some of your old brake fluid and put it in a small cup or container with a few drops of water. If you notice the water is not mixing with the brake fluid then it is silicone based (DOT 5) if you don't notice the water separating but blending in the brake fluid then it is DOT 3. Once mixed you want to wait at least 3-5 minutes or so before coming to a conclusion. If your entire system is depleted of brake fluid then it really doesn't matter. Just make sure you bleed everything out as to make sure you don't have the two brake fluids in there.

Thanks for the suggestions guys! I did do a little research here and saw the differences in DOT3 and DOT5...

My issue is I have ALREADY possibly mixed the 2? I don't know what was in there originally and in order to get home i filled up with DOT3 because A.) that was all the little gas station had, and B.) I figured it was the right stuff!!!

MY PLAN:

I am going to go to one of the wheels and bleed a little fluid into a cup and run the "do I have DOT 3 or DOT 5" test that OPCOM wrote up a while back... (also the same water test you mentioned WSUCOUGARX)

I am hoping that the fluids didn't MIX all the way down to the wheels yet... So hopefully what I bleed out of the brake itself will be the "OLD/ORIGINAL" fluid...

Going to bleed that fluid into a clear cup and apparently if I add equal part water - then the 2 should mix homogenously (sp?) But if they separate then the old fluid was DOT 5.

If they separate and I do have DOT 5 ---> then I am going to syphon out the reservoir/cylinder fluid and then fill with DOT 5 and just bleed each wheel until the 1 QT of DOT 5 I buy is empty...


Does this sound like a good plan of attack?

 

[doghead]

Don't forget to find and repair the leak that caused this dilemma! When is the last time you checked your brake fluid level?

 

[oifvet]

It's not going to hurt to do the full-system bleed anyway.

Over time, the DOT 5 looses its purple hue. You won't be able to look at it and tell the difference between it and DOT 3. When it's new, not a problem. You'll see the purple when it comes out the bleed fitting.

There are some threads on some really GREAT power-bleeder set-ups here on SS! Check them out and choose one. They are life-savers!!!

Here are some commercial ones:

Motive Products Brake Bleeders, JSC Speed

Brake Bleeding Made Easier With SpeediBleed Brake Bleeding Tool

BB100B, Brake Bleeder, Nondiaphragm Type

 

[papercu]

Did just adding brake fluid fix it? There should have been enough fluid in the rear chamber (rear chamber is for the front brakes)to stop it with no noticeable difference (except the brake light coming on). Wayne

 

[FMJ]

When is the last time you checked your brake fluid level?

PM Nazi. . .

 

[MuddWeiser]

Don't forget to find and repair the leak that caused this dilemma! When is the last time you checked your brake fluid level?

I haven't checked it since I bought it early 2007. This is my daily driver. I drive it EVERYWHERE and everyday! I love this truck. The scary thing is I just towed my boat up from the flatlands and it could of been bad if it had happened 2 days ago!

I noticed the brakes feeling a little "sloppy" yesterday and today the pedal felt really "slushy" it would go all the way down and hit the pedal stop and the truck wouldn't slow at all...

I crawled all around and didn't see ANY leaks... All hoses and connectors at each wheel seem fine. I fired it up in the garage and pumped the brakes for about 15 minutes and was hoping to see fluid on the garage floor but nothing yet. I am now taking a food break and hoping fluid will make its way to the floor so I know where I should start looking for leaks!

And I am finishing a soda so I have a "clear" bottle to use for my "what fluid do I have" test...

 

[FMJ]

If no leaks, your Master Cylinder is shot. . .

 

[MuddWeiser]

If no leaks, your Master Cylinder is shot. . .

Well I am thinking it has to be leaking from somewhere right? The fluid just doesn't disappear????

How can I test the Master Cylinder?

 

[FMJ]

Well I am thinking it has to be leaking from somewhere right? The fluid just doesn't disappear????

How can I test the Master Cylinder?

Check the seal on the MC cover, also check the firewall and the area near the hydraulic booster, on a gas powered truck this would be the Vac booster area.

 

[MuddWeiser]

Did just adding brake fluid fix it? There should have been enough fluid in the rear chamber (rear chamber is for the front brakes)to stop it with no noticeable difference (except the brake light coming on). Wayne

Well ya, adding fluid fixed the "squeeshy" brake peddle problem... It builds/holds pressure now... The rear chamber was FULL but the pedal was still going all the way to the ground. Once I filled the front chamber, the pressure got better after a few stop and goes...

Brake light NEVER came on...

 

[FMJ]

I'm voting bad master cylinder.

 

[doghead]

Two years, and you have not checked your brake fluid? Please check it once a month(or everytime you check your oil), it may save your life. Remember you are driving a 20+ year old vehicle.

 

[papercu]

Sounds as if you have NO front brakes, if you have just been using the rear to stop and use the truck a lot it is possible to vaporize brake fluid. Soft pedal may mean water in the system and could cause vapor lock. (DOT 5 Dry Boiling point is 500 degrees fahrenheit.) Wayne

 

[MuddWeiser]

Sounds as if you have NO front brakes, if you have just been using the rear to stop and use the truck a lot it is possible to vaporize brake fluid. Soft pedal may mean water in the system and could cause vapor lock. (DOT 5 Dry Boiling point is 500 degrees fahrenheit.) Wayne

Okay CRAP. I used the wrong fluid. I pulled some of the "mystery" fluid out of the rear chamber which I did not add to earlier. It came out a golden yellow color. I mixed it with water and it separated. I mixed a little with the DOT3 and they both separated.

After pumping the brakes in the garage (felt good) and checking for leaks I figured I would cruise around the block to check things out (and pick up some groceries). THERE WERE NO LEAKS anywhere. I followed all the metal lines at the wheels and under the frame and checked the front rubber lines. Checked the lines to the booster-equivalent and everything is good.

SOMETHING IS DEFINITLEY WRONG... Just backing down the driveway I had NO pressure in the pedal, again it dropped right to the floor however - once it "bottomed out" the rear brakes locked up and squealed down the driveway...

I then cruised around the street and pedal pressure is horrible. The pedal just drops to the floor - at the stop sign I again bottomed out and the rear brakes locked up and truck skidded to a stop.

THIS IS NOT GOOD. I got home and checked the fluid and it is full in both chambers.

THE REAR CHAMBER WAS NEVER LOW. The front chamber was the low chamber and has not leaked or gone down at all since I topped it off...


IM THINKING ITS THE MASTER CYLINDER? Im willing to replace it, its dirty and old and peace of mind is worth the $20-50 that it might cost to replace. Plus it might fix my current problem

DOES ANYONE HAVE A NAPA PART NUMBER? Or equivalent?

 

[papercu]

THE REAR CHAMBER WAS NEVER LOW

Right, but the truck didn't stop, that tells me the front brakes are not working at all. This truck has a split system if one go out the other will/should stop the truck. On the master cylinder the rear compartment is for the front brakes and the front compartment is for the rear.
The rubber lines can look good on the outside and be rotten and full of gunk inside. Even if you replace M/C you need to bled the system first and see if you have brake fluid at each wheel. Wayne

 

[MuddWeiser]

Right,

I suppose I could bleed the brakes first and see if I just got some air in the lines from the low fluid level - but I figure I will replace the M/C and THEN bleed the brakes... I don't mind spending money on this truck. I love it to death! It has been VERY reliable to me.

I doubt the front lines are "bad" as it all happened so fast... Just 2 days ago I towed my boat 100 miles and brakes were perfect, then all of a sudden today the pedal just drops to the floor...


DOES ANYONE KNOW WHAT MASTER CYLINDER I NEED? Can I just use the one the NAPA parts catalog calls for???