47-59 DOT 5.0 brake fluid question

[TX3100Guy]

I installed an all new set of calipers, rotors, and an electric hydraulic pump (frame mounted) on my 1953 truck a while ago. But if you've followed my other thread, I've had to deal with an engine rebuild and most recently a magneto rebuild/issue.

In any case, i've begun to button up other small tasks in getting ready to get the truck on the road for engine break in and testing all my other changes. Today I noticed a fine mist of DOT 5.0 brake fluid (what the mfg of the brake system recommended) on the passenger side front frame rail, just below the remote reservoir. A few weeks back, I had noticed the same fine mist on that same frame rail and deck of the four post lift just under that section of the frame. I was too occupied with other issues at the time, so I just wiped it up.

Today, I tried to figure out where this spray of DOT 5.0 is coming from. Lucky for me, DOT 5.0 is synthetic and doesn't remove paint, otherwise my epoxy shop floor would be a total mess. In my search, I noticed that two of the remote filler hoses that move the brake fluid to the master cylinder (also frame mounted) appear to be "sweating" brake fluid. The brake kit didn't come with enough filler hose to span the length from the passenger side remote reservoir to the drivers side master cylinder and hydraulic pump, so I bought brake line hose of the same diameter from O'Reilly's and it appears that those are the hoses that are sweating fluid, both at the hose clamp ends and along a partial section of the hose.

Am I imaging things? Does the synthetic brake fluid (DOT 5.0) require a different kind of hose?

[Hcb3200]

Did you buy bulk hose as in he cut it for you? Or was it specific packaged.

I have gone into a shop before asked for 4 feet of this and that and have not gotten what I expected.

Can you post the hose details lettering or picture.

If its sweeting wipe it down with a white clean cloth and confirm color fluid type.

I got fooled by some condensation before i thought was a overnight slow leak. lol. Just saying.

[TX3100Guy]

Originally Posted by Hcb3200

Did you buy bulk hose as in he cut it for you? Or was it specific packaged.

I have gone into a shop before asked for 4 feet of this and that and have not gotten what I expected.

Can you post the hose details lettering or picture.

If its sweeting wipe it down with a white clean cloth and confirm color fluid type.

I got fooled by some condensation before i thought was a overnight slow leak. lol. Just saying.

The hose has no part number marking. All it says alongs its length is "Replace every five years 070722". which I think is its manufacturing date. I purchased a 25 ft length and still have ten feet sitting right next to me.

Each hose clamp on both ends of the two sections I used are weeping the brake fluid. The hose provided by the mfg, does not. The mfg just told me that it is power steering hose made of ethyl propylene. I have found power steering hose online, but its doesn't say what its made of.

[Hcb3200]

That makes sense

EPDM (ethylene propylene diene monomer) is approved for brake fluid and is what you are looking for. Unless you know for sure that bulk hose is this flavor then I would confirm by looking at the reel it came off. Or by a 25ft roll off of online store confirming the hose type.

[TX3100Guy]

Originally Posted by Hcb3200

That makes sense

EPDM (ethylene propylene diene monomer) is approved for brake fluid and is what you are looking for. Unless you know for sure that bulk hose is this flavor then I would confirm by looking at the reel it came off. Or by a 25ft roll off of online store confirming the hose type.

From another auto project, I have a long length of Gate 4219BG Fuel Hose of the correct ID. I wonder if it would work? I can't find any info on what type of compound its made of.

[Hcb3200]

Fuel hose is normally not compatible as brake hose or power steering.
I would not use that.

[TX3100Guy]

Originally Posted by Hcb3200

Fuel hose is normally not compatible as brake hose or power steering.
I would not use that.

Thanks, that's what I thought, but wanted to get another opinion. I just ordered some fairly expensive power steering hose. It will be here alter this week and I'll get it cut and installed shortly.

[dsraven]

what typeof hose clamp are you using? a regular gear clamp may not be enough as it doesn't have a conplate circle of banding where the gear section is located. it is flat on the back side nehind the gear section and can allow some leakage, especially on a fluid that tries to find any way out of a vessel. maybe try a fuel injection style clamp that fits the hose connection well. there are a few different styles of full circle style clamps you could try if that turns out to be the problem. here are a couple links with pics. there is a gear clamp with a "liner" wrap behind the gear part that I have seen used on fuel injection hoses.

https://surplustek.ca/en/atlas-10-fu...se-clamps-7-16

https://www.grainger.ca/en/product/H...K10/p/WWG1XGY9

https://www.huyett.com/blog/hose-clamp-types

[dsraven]

some power steering hose has steel wire reinforcement, like a hydraulic hose, and will require a crimped connection on the end to seal properly. power steering return hose is more like a fuel hose with "cotton fiber" reinforcement so a regular hose clamp is usually enough to seal it, considering it is not a pressure hose.

post a few pics of what you have, don't think too much into it, check the hose, and the nipple that it fits onto, and decide what is required to seal the connection.

[Hcb3200]

i was going to say. that I would be surprised if a hose started weeping like that so fast and you would think it would be the whole hose and not just the ends.

I am with dsraven make sure its actually sealing on ends and hose is not to large for connection or that hose clamp is correctly sealing like he suggested.

[TX3100Guy]

I have the fuel injection type of clamp on the three hoses at the remote reservoir, mounted on the passenger side firewall. Tow of the three hoses are weeping on the remote reservoir and its the two where I supplied the hose from O'Reilly's.

On the two hoses that are weeping at the mater cylinder, I formerly had fuel injection type clamps and in an attempt to stop the weeping I changed over to the worm gear style.

I should note that the thrid hose, supplied by the mfg in the brake kit for the truck, neither end is weeping regarless of the clamp style. Also, along some portion of the hose, it is shiny and when I wipe it, I'm getting brake fluid, not a lot, but some.

The brake hose that I ordered is power steering return line, as in low pressure without the spring insert that needs crimping. I will start with fuel injector type clamps and hope for the best.

[57tailgater]

I imagine the fluid is seeping/sweating through an incompatible hose inner tube. This is critical and needs to be compatible with any fluid/application. I have witnessed the "sweating" you're seeing and once providing a customer the correct hose, all was fine. I imagine the spray your seeing is the weeped fluid being blown around by driving and fan blast. I suggest contacting a hose manufacturer directly to see what's compatible. They should also have a compatibility chart listed in their catalog or online as well.

[mr48chev]

I had to read that a couple of times to make sure that I did not have the wrong answer and then studied up on dot 5 brake fluid a bit.

What I found is that dot 5 is not compatible with Viton but does not eat paint nor does it absorb water like dot 3 does and the boiling point is a tad higher than others but it does not have the same properties as silicone brake fluid. Remembering that Silicone brake fluid was first sold on Corvettes and the big deal was that if you spilled it on paint it didn't eat the paint like Dot 3 does. Street rodders went for that whole hog.

In the end my thougts are that on your hoses from your remote reservoirs the hoses are just not sealing right on the fittings on the master cylinder for one reason or another. Either hose size vs fitting size, clamp design or hose composition. My other thought is if there is the least bit that brake fluid can leak brake fluid will find that least bit place. Even without pressure the same setup that will seal off gas, oil or coolant may not handle brake fluid.

[dsraven]

I am wondering if the fittings can be replaced with something that has a more positive mechanical seal. something like the steel braided brake lines with banjo style fittings that have sealing washers, a flared fitting like the high pressure brake lines use or even a pipe thread. a hard line could even be used. once and done and they look great under there as well. I am also curious what the fittings look like where the hoses are connected. are they smooth with a bulbous end to keep the hose from coming off? barbed? do the fittings screw in so they could be replaced with something that has a more positive seal type? like mr48 says, brake fluid seems to find any way possible to seap out. also curious how the system vent looks, to ensure there is no pressure if that may be adding pressure to your system.
do you have a brand name or some pics of the hydraulic pump? is it a system like a hydroboost?

[mr48chev]

There should be no pressure on that line between the reservoir and the master cylinder.

As others said regular fuel line may not be compatible with the brake fluid but without asking the hose maker I question just running out and ordering power steering hose to do it. You would have been far better off to go to a local Aeroquip or Parker hose dealer and ask what hose you need that will be compatible with it.

Also something to consider is hose ID and fitting size. You have to know with the sizes are and if they will work together.