Encountering a bypassed heater core with exposed, damaged pipes can be a frustrating discovery for any car owner. Recently, upon purchasing a vehicle, I faced this exact issue: the heater core was bypassed, leaving two uncapped copper pipes protruding from the firewall. Closer inspection revealed crushed and out-of-round pipe ends, with a notable crack on the “In” hose, closest to the engine. While a complete heater core replacement initially seemed inevitable, a more resourceful and cost-effective DIY repair emerged. This guide details the process of fixing cracked car heater pipes using readily available tools and materials, ensuring a functional and leak-free heater system.
The first step involved addressing the deformed copper pipes. To restore their roundness, a technique using deep sockets as makeshift hardline tools proved effective. By carefully tapping successively larger deep sockets onto the pipe ends, the crushed sections were gradually reshaped back to a more circular form. This crucial step prepares the pipes for a secure and leak-proof connection with new hosing.
Next, the cracked inlet hose required attention. To overcome the crack and establish a reliable seal, a section of 5/8 ID heater hose was employed. Approximately 7-8 inches of this hose was twisted and fed through the firewall, extending about 4 inches into the cabin until it reached the first clamp on the white plastic heater box. Applying Shin-Etsu silicone grease to the copper pipe beforehand, both in the engine compartment and under the dash, is essential. This lubrication significantly eases the process of twisting the hose into place and ensures a snug fit. Silicone grease is preferable as it is rubber-friendly and prevents degradation over time, unlike some regular automotive greases. To accommodate the wider heater hose, the existing grommet at the firewall was carefully enlarged using an Exacto knife.
Securing the newly installed heater hose section is critical. Two hose clamps were applied under the dash on the pushed-in section. One clamp was positioned about an inch from the firewall, and the other near the end of the hose. Additionally, another hose clamp was used directly over the crack on the engine side. Care must be taken when tightening clamps on copper pipes, as they are easily deformed. Properly tightened clamps ensure a leak-proof seal at all connection points.
After securing the initial hose section, the excess heater hose was trimmed. To facilitate the turn towards the back of the engine, where the hose connects, a 90-degree plastic elbow with barbed ends was utilized. This elbow, readily available and inexpensive, ensures a smooth coolant flow path. A new section of heater hose was then connected between the elbow and the engine connection point near the CAS (Crank Angle Sensor). Hose clamps were applied to all connections – on both sides of the elbow and at the engine – to guarantee a secure and leak-free system. The clamp size used was #8.
With the physical repairs completed, the next step involved back-flushing the heater core and cooling system. A Prestone flushing tee, installed in the “Out” hose (nearest the fender), was used for this purpose. The back-flushing process revealed a significant amount of rust and crud, indicating the system contained water instead of antifreeze. Following the initial flush, Prestone “Super Flush” was used, and finally, the system was refilled with antifreeze.
This DIY repair, utilizing basic hardline tools like sockets in conjunction with heater hoses and clamps, proved to be a successful and durable solution. After three weeks, the repair showed no signs of leaks, and the car heater was functioning effectively. This approach offers a viable alternative to complete heater core replacement, especially when dealing with damaged pipes.
In conclusion, repairing cracked car heater pipes can be achieved with careful DIY methods and readily available hardline tools and materials. By reshaping damaged pipes, utilizing heater hoses for secure connections, and properly flushing the system, car owners can restore their heater functionality and avoid costly replacements. This step-by-step guide provides a practical approach to resolving common heater pipe issues, ensuring a warm and comfortable driving experience.
