Brake Hose Question

Some years ago I had a situation where I had to replace my front brake hoses because they had gotten "hard." I was told by a fellow X enthusiast that the reason that my brakes would lock up when depressed was due to "hardened" brake hoses.

Well, I am having a similar situation with my truck (hope you don't mind solving a non-X problem). When I depress the brake pedal, the caliper piston clamps onto the rotor, but does not release when I take my foot off the pedal. As with my X, I've replaced the brake caliper and brake pads but the problem persists. So, what is happening? If it is a "hard" brake hose, what does that mean, and why does it cause the caliper piston to not release?

With my X, replacing the hoses solved the problem, but I still don't understand why. Now, I am wondering if this is a general remedy for sticking brakes.

Thanks for your enlightenment.

Don

brake hose

Brake hoses have a tendency to collapse internally, trapping the fluid and not allowing the caliper piston to retract upon release of the brake pedal. This condition normally worsens with age.

ddoan said:

Some years ago I had a situation where I had to replace my front brake hoses because they had gotten "hard." I was told by a fellow X enthusiast that the reason that my brakes would lock up when depressed was due to "hardened" brake hoses.

Well, I am having a similar situation with my truck (hope you don't mind solving a non-X problem). When I depress the brake pedal, the caliper piston clamps onto the rotor, but does not release when I take my foot off the pedal. As with my X, I've replaced the brake caliper and brake pads but the problem persists. So, what is happening? If it is a "hard" brake hose, what does that mean, and why does it cause the caliper piston to not release?

With my X, replacing the hoses solved the problem, but I still don't understand why. Now, I am wondering if this is a general remedy for sticking brakes.

Thanks for your enlightenment.

Don

Click to expand...

This can happen on any brake hose. The small hole inside the hose breaks down as the hose ages and flexes causing bits of rubber to come loose and work like a one way flapper valve.
When you step on the brake the fluid goes passed the flap and when the peddle is released the back pressure from the brake pushes the loose rubber back blocking the fluid. Step on the brake again and more pressure builds up. The only fix is new brake hoses.

Only one cause...

The other cause is corrosion in the bore between the bore and the piston, which normally the seal and dust seal protect. Enough corrosion and the piston will move with M/C pressure, but not retract as would be expected, some say the seal design promotes a slight retraction when the pressure is released.

The fix is a caliper rebuild or replacement. Some aftermarket caliper rebuilds have had their protective coating cleaned off and will corrode more quickly than the original one.

Well Don, I find it also helps to...

keep us GUESSING at what year, make and model truck you are talking about. (HA!)

Most modern vehicles have all sorts of gadgets and proportioning valves as well as ABS and super master cylinders.

I haven't found a collapsed brake line in the last 50 years on anything but old Fiats X1/9's and maybe some 124's. I'm sure they are out there, but most I have found have burst or leaked... and that's kinda rare as well.

I think if ya give us some more info we could possibly direct you with more specifics than with (even intellectual) philosophical guesses.

Well, Tony...

It's a 1978 Chevy C30 (1-Ton) pickup with GVW of 9000 lbs. Like you, my parts guy is dubious that it's a brake hose, but I'm at a loss to know what else it could be - and hoping it's as simple as the hose. I'll be picking up a new one this morning and will see.

I have a Haynes manual, but haven't found a troubleshooting fix for my problem, so I'm flying blind, relying on my experiences with old Fiats and Lancias. I have found that replacing brake hoses have solved the identical problem.

I'm always open to philosophical and intellectual discussions.

Don

OK then... and are their disc brakes in the rear as well?

If so... they should have the e-brake expanding shoes inside the drum which could be another possibility for lock-up in the rear.

This is a TYPICAL drawing of MOST brake systems but I'm not sure if it truly resembles yours. Note the possibility of Residual Check Valves, Combo Valves, Proportioning Valve and many more... All this stuff can be a contributor or the actual problem.


Lastly... and I dunno where to look for this... but some trucks did not have a vacuum assist power brake... They used a HYDRO-BOOST system... which used an external pump like a power steering pump to operate it. I know absolutely nothing about the details of this or if your truck has it... just sayin'.

If replacing the flex line doesn't work and you have difficulty identifying and testing any or all these parts... then I suggest you bite the bullet and call around to dealers and other specialists that are FAMILIAR with your system. Hopefully this helps...

re: brake hoses

Having worked in the automotive industry, at many dealers, and indies, including my own, for over 40 years I can emphatically say that internal brake hose failure is not as uncommon as one might think. I have replaced at least 50 of them for this very problem. It should be easy to detect.
With the caliper in "hangup" mode simply loosen the bleeder and attempt to spin the wheel. If the offending wheel will then spin the brake hose is the culprit.

Thanks for that...but...

...I have been trying, unsuccessfully, for most of the day to remove the brake hose. On this model truck, the inboard fitting is located in the frame of the truck. The idiots who engineered this era of Chevy products made every conceivable effort to make working on them next to impossible. The hose fitting at the frame is round, with two opposed flat surfaces - whereas the new hoses have hex fittings. The location of the fitting, the accumulated rust, and the weird shape of the fitting have made it impossible to unscrew. At least with the tools that I have.

The good news is that the test that you suggest is exactly where my logic led me. With the piston locking up the rotor, I backed off the bleed screw, a small amount of fluid spurted out, and the wheel was free. So, we know that fluid is flowing in one direction, but not the other.

I'm really stumped at knowing how to unscrew the hose, though. I'd cut the hose so that I could engage a socket, but I don't think that would work with the round fitting. It needs to be a tool that can grab the fitting - like a vise grip - but configured like a socket. Any ideas. I'll pay good money to obtain such a thing.

If I could keep my sanity, I should start a list of all of the big and small screw ups with the engineering of this vehicle. I'm not sure if there is enough ink available to complete the task, though.

Don

None of the vehicles in the running fleet have brake hoses over 10 year old.

None of them have OE hoses.

All have been upgraded to DOT-TUV approved PTFE/Stainlesss Steel/clear covered brake hose. These are also on a replacement schedule.

When the 74' arrived, both rear brake hoses were OEM from 1974, never changed or replaced. Both rear brake calipers were non-functional. First time trying to flush the brake fluid out of the system, only a few drops of brake fluid appeared from the brake caliper bleeder boss. Or, after the brake bleeder fitting was removed, a few drops of brake fluid appeared at the M8 x1.25 internally threaded hole.

Both rear brake hoses were aged and collapsed to the point where applying 1200+ psi resulted in virtually zero fluid flow.

Brake hoses should be replaced as a scheduled service item. No hose last for ever and to expect more than a decade of service from any hose is IMO, expecting too much.

Some one explain why are hoses so neglected and taken for granted that they last for the life of the mechanical device and when there is a problem, grief results?

As for the type of replacement hose, use the best that is available on the market for a specific application. Skimping on hose quality is asking for problems and grief.


Bernice

Image of the offending part and related area?

Details of what wrench sizes are involved and some ability to gauge the service area can go a long way to figuring out what can be done.


Bernice

ddoan said:

...I have been trying, unsuccessfully, for most of the day to remove the brake hose. On this model truck, the inboard fitting is located in the frame of the truck. The idiots who engineered this era of Chevy products made every conceivable effort to make working on them next to impossible. The hose fitting at the frame is round, with two opposed flat surfaces - whereas the new hoses have hex fittings. The location of the fitting, the accumulated rust, and the weird shape of the fitting have made it impossible to unscrew. At least with the tools that I have.

The good news is that the test that you suggest is exactly where my logic led me. With the piston locking up the rotor, I backed off the bleed screw, a small amount of fluid spurted out, and the wheel was free. So, we know that fluid is flowing in one direction, but not the other.

I'm really stumped at knowing how to unscrew the hose, though. I'd cut the hose so that I could engage a socket, but I don't think that would work with the round fitting. It needs to be a tool that can grab the fitting - like a vise grip - but configured like a socket. Any ideas. I'll pay good money to obtain such a thing.

If I could keep my sanity, I should start a list of all of the big and small screw ups with the engineering of this vehicle. I'm not sure if there is enough ink available to complete the task, though.

Don

Click to expand...

Photos of Hose Fitting

I should have done this earlier. Here are two photos of the brake hose fitting that is located on the frame of the truck.





As you can see, it is chewed up a bit, but the flat sides are to the left and right of the fitting. That's all there is to get a grip on. The greenish discoloration around the fitting is some crayon that I used, in addition to PB blaster to try and loosen the fitting.

The question is, what kind of tool is available to get into such a tight space and get a bite. Or, is there a way to grind the thing out without messing up the female threads?

Thanks for any help or advice.

Don

My guess is that the other side has a similar arrangement...if so, it looks like they are sandwiching the meat of the frame between the flanges of the flex hose on the outer portion and a similar flange on the hard line on the inner portion.

If my guess is right, you'd have to grip the inner unseen part of the connection to stabilize it and then after the hose is disconnected from the caliper, grip the visible portion of the hose's inner end to turn it counterclockwise to remove from the flare nut on the hard line.

Looks like you need to get a fine mill bastard file and file the visible portion of the hose inner end to restore the two opposing flats that were originally there. Or if you have it available, use a dremel with a stone, rotary rasp, or cutoff wheel and a steady hand to restore the two flats.

Before filing, apply penetrating oil to the unseen back side of this joint as that is where the threads are. That way, during the time it takes to file the hose inner end, the penetrating oil will have a chance to work a bit.

When it comes time to try to loosen that joint, I'd use my best adjustable wrench on it....chances are filing the flats will leave then some in-between size that will be too loose for the open end wrench size that the flats originally fit. Vise grips will initially stay in place but will concentrate their grip on too small of an area and will deform the metal and come off, compounding the problem. Be sure to turn the adjustable wrench in the direct of the moveable jaw.

brake hose headache

the frame holds the hose and keeps it from spinning on the other side, if I'm not mistaken the frame is open or just "c" channeled and the hard line can be accessed. there you can use a crows foot or a flair end wrench to loosen the hard line. there should be a flat metal clip that fits through a groove in the hose to maintain the
rubber hose.
good luck and keep us posted!!
mikemo90*aol.com

Unfortunately...

...the backside of the brake hose fitting is inaccessible without removing the fuel pump and some other lines. It is clear that all of these parts were put in place on the frame before the entire engine and engine accessories were dropped into the truck. Even putting in a replacement fuel pump was a nightmare, since it is right up against the frame. For such a big engine bay, there is very little working space. A 454 motor is really, really big.

The Hanes manual simply states that the hose is to be unscrewed from the frame junction, with no mention of having to access the fitting on the backside of the frame. I've been wondering if it might be possible to cut the fitting and insert some sort of EZ-Out into the lumen and back it out that way. Even if I could repair the flat sides of the fitting, they are only about 1/16" deep. No wrench, adjustable or otherwise, will bite into that. Plus, the turning radius of my wrench handles are longer than available space all around the fitting.

Keep the ideas coming. It is supposed to rain, today. So, the project is on hold until tomorrow.

Don

Pic of the backside?

Can you tell if the pass side is made the same way?

Pic of the replacement hose?

More Hose Photos

Here are two photos of the replacement hose. Note, it is a hex type fitting with a retaining piece that keeps the hose from going past the frame. That retaining clip seems to be solid on the original. Also, the thickness of the hex portion is at least twice that of the original - making it easier to grip with a wrench.

I am guessing there is a hard line with a flare fitting on the back side of the frame rail? If so, I think you'll have to undo the flare fitting on the back before you remove the flex line or you will damage (twist) the hard line.

+1 on Dan's idea

If this is the driver's side, do you have visibility to the inboard part of the PASSENGER's side? Can you tell if the two sides are about identical? Can you get pictures of that other side?

BTW, if you tape a spare FIAT badge to the truck it will make this whole discussion legit. I base that on how much time we spend with Hussein (lookforjoe) talking about his X1/Volvo.

Most common tool used to deal with fittings like this is a crowfoot wrench on the end of an square drive extension.

These come in open end and semi-closed end for flare and similar fittings. Sizes range from 3/16" to well past 4" and in metric sizes too.

The flare style crowfoot is the tool to use for tubing and hose situations like this. They are extremely common for plumbing work on aircraft, aerospace plumbing, automotive, industrial plumbing and earth moving and similar machinery where tube fittings and hoses are used a lot.



What size hex is on the end of that brake hose?

If the wrench flats have been damaged, these will not likely work due to the significantly reduced wrench grip area.


Bernice

ddoan said:

I should have done this earlier. Here are two photos of the brake hose fitting that is located on the frame of the truck.





As you can see, it is chewed up a bit, but the flat sides are to the left and right of the fitting. That's all there is to get a grip on. The greenish discoloration around the fitting is some crayon that I used, in addition to PB blaster to try and loosen the fitting.

The question is, what kind of tool is available to get into such a tight space and get a bite. Or, is there a way to grind the thing out without messing up the female threads?

Thanks for any help or advice.

Don

Click to expand...