What's the Shortest Brake Hose Life You Have Seen?

I have had a few cars over the years that have had a problem where the brakes work, but won't disengage when you let off the pedal. This always seems to be the flexible brake lines failing. They come apart from the inside and begin to act as a valve instead of a hose, thus keeping the pressure on the brakes by refusing to allow fluid to move back toward the master. 

The last time I saw this was on a 1978 Spitfire. The lines looked original. A quick swap to a set of braided lines did the trick. I figured that forty years was a pretty good lifespan for lines, if these were indeed originals. 

So fast forward to another Brit--a '71 E-Type Jag Series 2. Same symptoms. But when I went through the documentation for the car I saw that the lines had been replaced only 5 years ago. Five years? That seems ridiculous. 

That's the question: Has anyone seen these lines fail in such a short time? It's possible that these lines were not factory, that they may have been sitting on a shelf for decades, or that the car sat around a lot once these lines were installed.

Anybody have any thoughts on this?

Thanks~

Maybe the type of brake fluid used was not compatible with olde English rubber...  just a thought.

Purple Frog (Forum Supporter) said:

Maybe the type of brake fluid used was not compatible with olde English rubber...  just a thought.

I gave that some thought, but the shop that did the lines and presumably selected the fluid has impeccable credentials.

Shortest life I have seen was caused by rust.

I would also suspect fluid incompatibility 

Agreed, incompatible brake fluid, old "NOS" with more "O" than "N" or crappy cheap parts.

I've seen '09 Chrysler T&C front lines fail in 5 years.

Maybe the shop with the "cred" let the lowest man on the totem pole put in the fluid.  Just saying.

The key is the pedigree of the parts.  Some of the junk being sold by parts stores nowadays is pure garbage.  Five years is probably some kind of record.

My OEM Volkswagen lines went nearly 11 years before I replaced them with Goodridge stainless steel lines because I suspected that there was some flex causing a slightly squishy pedal at the track. My suspicion was correct, but on the street I wouldn't have noticed a difference... the rubber lines could have given me more years.

The first thing I check when my brakes start to feel sticky are the slide pins.

I saw this failure on a one year old Ferrari 365 GT. I suspect it was bad from day one, and it didn't get to me until the warrantee expired. It did not lock on completely, but it was also restricted in the application direction. The car would briefly pull one way on application, and the other way on release of the pedal. I have seen it many times on Fiat124s and old Toyotas in the 5 year old range. Unless someone used silicone fluid I would not blame the fluid for the failure on the Jag, but the current quality of reproduction parts for all of the obsolete British cars is dismal. If it works out of the box I am surprised.

I've seen OEM lines fail like that in five years.  It's usually due to the metal crimp or brackets rusting and pinching the hose.

I pulled the first hose off at lunch. I will do some some surgery when I have a chance and see what the guts look like. 

AaronBalto said:

I pulled the first hose off at lunch. I will do some some surgery when I have a chance and see what the guts look like. 

Please post pictures!

I have often heard of the "check valve" from failing rubber lines but have only experienced sticking pistons and or sliders. And I have run a decent amount of old rubber lines. 

Here's the latest on this. I replaced the two front lines with new braided steel and bled the front circuit. If anything the problem became worse with the brakes dragging more and more as they got hot. The front calipers don't seem to really be getting hot.

Next, we put the Jag on the lift and replaced the single rear soft line with braided steel. Bleeding the rear brakes is not easy. The car has inboard rear brakes. At the time this must have been impossibly cool engineering. But it required packaging that makes things very, very tight. You cannot turn the bleeder screws a full quarter turn, making the process a bit of a hassle. It is also challenging to get the bleeder hose on the nipple because of the clearance. 

I was sure that this rear soft line was going to be the problem. When I cut it open, though, it was fine. I would post a pic but it's just a normal looking brake hose. 

But the bleeding process itself seems to be helping. It's better, but still not really 100% correct. It's not as bad as it was. So the next step is probably to go ahead and bleed the rear system again. I'm thinking that this may actually turn out to be a bunch of crud in the system that is gumming things up. The more I use the brakes, the more crud gets stirred up and the more problems I seem to have. 

Unfortunately, it's about a billion degrees F outside today and I really don't feel like working on this for a second consecutive day in these temps. I'll wait for things to cool off and then we can take another crack at it...

Have you checked to make sure the master cylinder pushrod is not too long?

I've seen a new brake hose last about 10 minutes, but that was because the guy that installed it didn't give it a little twist before tightening the nut in the chassis flange to give it a bias away from the tire  - idiots abound. Lasted about 2 laps.

Much to my surprise I once had an Aeroquip line on one of my race cars pinhole and spray brake fluid, fortunately while I was bleeding the brakes. Being Teflon liners with reinforced braided steel outers I hadn't thought they were liable to do that.......

And yes, I always changed all the brake hoses on a car when I restored it and periodically thereafter - am in the process of doing that to my 72 Jensen Interceptor right now