Advice for on-the-road wire and hose repairs
Story and photos by Wes Trindal
Sometimes, the various hose lines and electrical harnesses of vintage vehicles begin rubbing on each other and chafing against other components. Most serious are the lines that break during operation or while performing preventive maintenance. Vehicles are totally dependent on the timely delivery of fluids – hydraulic, air, coolant, oil, and fuel through hoses – and of electrons through electrical system wires and components in a variety of vehicle components.
The best way to prevent problems in wires and hoses is to evaluate, emancipate and eliminate or, at least reduce, the effects of rubbing and chafing of the lines by protecting, securing and rerouting them. The following guidance to protect lines in trouble places is recommended in the following preferred order:
PROTECTION OF LINES
It is best to protect lines with a sacrificial covering, especially in areas where the lines must remain flexible. Examine the vehicle for potential trouble spots and look for signs of wear. For areas at risk, cut and slit a length of old garden hose, or scrap water hose of a heavy type.
Slit the protective hose so as to slip it over the line: for short lengths, make straight cuts and, for longer ones, spiral cuts work best. Install the slit hose over the lines, letting the added hose shield the vulnerable lines from wear. Secure the ends with screw-type hose clamps, installing at least one on each end. Check the wear at intervals, and be sure to replace the sacrificial hose sections as necessary. Another solution is to use hose as a continuous, flexible bracket around the line, but avoid the offending object.
With the added hose, the line becomes stiffer than the line alone. This degree of stiffness can help with the line routing to avoid contact with other parts. A sharp knife, kept wet with water, cuts the rubber hose best. Fill any open ends with wraps of tape or Dum-dum-type putty and apply paint to match.
Brackets are good, but there are a number of tricks of the trade necessary to prevent the brackets from causing more problems by cutting into lines. The purpose of any bracket is to clamp and secure the line out of harm's way. Make sure that any bracket added by this will:
(1) Hold the line away from danger, and not be in the path of future trouble,
(2) Won't chafe the line – wrap the bracket with tape or install soft sleeves,
(3) Prevent movement between the line and the bracket, secure the line onto the bracket, but, in the case of hose, never crush nor kink the line. Be aware of the minimum allowable radius for the original hose.
CAUTION: Do not fasten additional brackets onto vehicle components that could result in new, increased maintenance problems, such as the following:
(4) Do not attach a bracket under the heads of torqued cap screws that could cause gasket leaks.
(5) Watch attaching a bracket that creates a "blind component," one where the line is hidden and can't be easily seen and disconnected by the mechanic, during removal. Foolproof all brackets to ensure that the line is not damaged.
(6) Do not drill holes, except when necessary. Never drill holes in highly stressed, heat-treated frame rails. These members must remain free of any added holes, which could cause stress risers leading to cracks.
Find existing holes. Use Grade 8 bolts and prevailing-torque (lock) nuts or coat the threads with nut adhesive. Never depend on sheet-metal screws.
(7) Don't employ flimsy, light-duty brackets. Consider the worst case-use, with all of the heavy shocks and vibrations of road use.
(8) Never install a twin-legged bracket that would be attached to two different parts on the vehicle. Separate vibrations will crack the bracket and allow the line to get damaged.
Rerouting lines is sometimes necessary to solve a problem installation. On all vehicles, the safest place for lines is in the upper, inner side of channels and framing members. Route the lines away from hot surfaces, and from moving and articulating components. Get them out of reach of mud, debris, branches and road-splash areas.
Prime candidate lines also are those lines spanning the open space between the chassis and the body, plus those lines that can be stepped on by maintenance personnel.
Line rerouting can be tricky and needs trained eyes to evaluate all possibilities. Before any relocation attempt, obtain a length of scrap line and make a trial installation. Temporarily secure the line in the new location.
Review the installation for other hidden hazards. Even ask other personnel to review the rerouted pathway. Then, when sure that the new path is satisfactory, change the line to the new location. If longer or shorter lines are required, remember to measure the length needed twice, and then cut to the new length just once.
Now, do it right and heed the minor details.
The suggestions in this article originated with the Army Corps of Engineers in a "Maintenance Work Order‚" written by Corps of Engineer Construction Battalion troops in the 1970s as a result of receiving Unsatisfactory Equipment Reports (UERs) related to military vehicles. Troops cited their troubles with the new Commercial Construction Equipment (CCE) end items that were being distributed worldwide. The author of this article originally answered these UERs while he was in the Mechanical Engineering Division, Engineer Research & Development Laboratories, Fort Belvoir, Va.
Wires or hoses that are not controlled, are prone to chafe. Follow this "Modified Work Order" to avoid failure as a result of worn-through wiring and plumbing.