[STEELCITYFIREBIRD]

So I encountered my first Bonne-fied plugged brake hose on my '98 Bonne. Won't pass compressed air from either direction. Was dragging brakes heavily.It was acting like a check valve, as when I cracked the bleeder it would release, but tighten back up on the very next application of the brakes and drag heavily. Crack bleeder, repeat.

So what usually happens here?
Hose deterioration or foreign material?

I am going to do an autopsy but don't want to lose the cause in the dissection. My plan is to cut each end off and check for restriction, then keep cutting the remainder in half length wise till I find the restricted part of the hose.

I gotta know the cause.... just cause that's my nature!

[Torquewar]

Oh...been there and talk about frustration. Yes i understand the your nature..
Had that same deal on a rear line (91 Caprice) had casting flash im guessing from a master cylinder.
It caused me increased blood pressure at times and a few descriptive adjectives that verbally bounced off the walls of the garage..
Report the findings.

[steve25]

Did this take place after installing a rebuilt Caliper or master cyl?

[firechickenman]

Does the hose have a metal bracket clamped around it? Very common for rust to build up between the bracket and hose and pinch off the hose.

[Keith Seymore]

Also very common for the hose to deteriorate and the inside of the hose collapse, causing what you have described.

K

[Sirrotica]

Originally Posted by firechickenman

Does the hose have a metal bracket clamped around it? Very common for rust to build up between the bracket and hose and pinch off the hose.

I have found this condition, rust forms on the inside of the bracket slowly growing over the years until it shuts the flow off, creating a effective one way check valve. Usually associated with the calcium based snow melting applications in the northern rust belt.

Many years ago I had a customer with a 77 Bronco, fairly new vehicle at that time, that if you jabbed the brakes in a non emergency way, would yank the wheel out of your hand and dart very unpredictably right or left. Speaking to a ford parts man he confirmed they had several 4X4 vehicle in the service department exhibiting these characteristics and found a deteriorated inner layer in the flex hoses that would create a flapper valve. The phenomenon was a material based defect. It depended upon application pressure and was unpredictable when it would rear it's head. This was in the late 70s, and was the first flex hose problem I had seen that would shut off brake pressure causing very strange brake problems. I never dissected these particular hoses, but new front flex hoses cured the problems.

This particular vehicle was owned by the son of the owner of Seaway Aluminum, a local window and door manufacturing plant in Erie PA. My ability to fix the problem in this particular vehicle earned me a fleet account for the entire company. A lucrative deal on my part, I was very happy to be able to get this account due to the son having taken the vehicle to other repair facilities, and the problem was never properly diagnosed or repaired.

[jonmachota78]

Ive had this happen a few times. Just happened on my 99 Silverado. Also my daughters 2000 taurus and my old 95 c1500.
Tell tale sign is when you hit the brakes and it pulls one direction, let off the brake and it pulls the opposite direction. Ive only seen it happen on front brakes.

[STEELCITYFIREBIRD]

It does have a support bracket. I replaced pads and rotors only August last summer. Probably 1000 miles max since then.

[77 TRASHCAN]

The hoses usually collapse where the metal ends are crimped on to the hose, could happen at the bracket attachment point. Was working on an older car, 20 years ago or so, recognized what was going on, ordered new hoses. Experimented with old hoses after the new hose install obviously made the repair work.....took a small drill bit, opened up both ends of hose (this hose obviously had short fittings on both ends, a drum brake car), was able to blow air easily through hose......who knows what hydraulic pressure would have done...

[STEELCITYFIREBIRD]

As bad as the brakes were dragging on the left front the car coasted straight. It had a weird dive to the RF when you applied the brakes firm and quick, but no noticeable pull like you would expect. The drag was so bad after the brakes heated up you could stop on a hill and the car would hold it's place with out applying the brakes. Fuel mileage was getting real bad!
I have never found this problem before, although I have heard many accounts of it.

Autopsy results to follow.

[STEELCITYFIREBIRD]

Autopsy results:
>Retainer bracket rust pinched the hose shut.
>Inside of hose looked fine everywhere else.

[Schurkey]

Both front hoses from my "disc brake donor" Toronado were plugged. (no bracket to rust)
Rear hose from my El Camino was plugged (no bracket to rust)
I'm fairly sure my rear hose on the Toro is now plugged, although it wasn't when the Disc brake swap was first completed. (No bracket to rust.)

Sometimes the hoses just swell shut internally. I know this because...I cut the hose apart and looked inside.

[STEELCITYFIREBIRD]

Mine may very well have had atherosclerosis, but the rest of the hose was fine and the restriction was @ the bracket from both ends. First time I ever came across this myself. Have heard of many accounts from others.
Thanks for all the replies!