“What I Learned Today” With Jeff Smith: Brake Hose Failure

This one had us baffled for a short time. We resurrected my son’s ’65 El Camino that had been in storage for about five years. We installed a new battery, rebuilt the carburetor, and had the car running for a short time before we realized the rear brakes were dragging. The evidence was smoke coming from the rear drums after a short drive on the highway. 

When we first inspected the hose on the car, it looked okay as with photo A. But a closer inspection (photo B) revealed these small lumps in the hose that indicated it had failed even though it did not leak. 

We noticed there was residual pressure in the rear hydraulic circuit that kept the wheel cylinder pistons applied. The car was equipped with a rear brake adjustable pressure regulator so we assumed that was the problem. We purchased one from Summit Racing and installed the new valve but that did not solve the problem. Even worse, now very little pressure was being applied to the rear drums. We next looked for a kink in the line was restricting the flow. We could not find one which left the flexible brake hose as the only other possibility. A visual inspection of the hose did not indicate it was bad, but after we removed the hose an air nozzle with 100 psi pressure test could not force air through the hose so clearly it had collapsed internally. 

We purchased and installed a new rear brake hose and now the brakes work properly. A close inspection of the old hose revealed small lumps that indicated the hose had separated internally. In the future we plan to replace the other front hoses just to avoid this issue in the future. Another mystery solved. It just took us longer than normal to diagnose the problem. 

About the author

Jeff Smith

Jeff Smith, a 35-year veteran of automotive journalism, comes to Power Automedia after serving as the senior technical editor at Car Craft magazine. An Iowa native, Smith served a variety of roles at Car Craft before moving to the senior editor role at Hot Rod and Chevy High Performance, and ultimately returning to Car Craft. An accomplished engine builder and technical expert, he will focus on the tech-heavy content that is the foundation of EngineLabs.
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