How to bypass the heater core in 1997-2003 F150

by James Webber
itstillruns article image
truck speeding down the street image by Larry Roberg from

When the heater core fails in a 1997-2003 F150 the truck will begin to bleed antifreeze quickly. This is because the core itself is compromised. Symptoms that indicate broken heater core: heater no longer works, cabin of vehicle smells like antifreeze, the windows fog when the heater is running, antifreeze leaks onto the ground or inside the cabin, and the engine overheats if it runs for too long. Luckily, there is a quick fix for this problem that does not require a mechanic or replacing the core. This solution is bypassing the heater core by connecting its inlet and outlet hoses together thereby removing the heater core from the system.

Step 1

Open the hood of the truck and look on the passenger (left) side of the engine compartment. There will be two black hoses (about 1 1/4-inch OD) that run side by side into the firewall behind the engine. These are the inlet and outlet hoses to the heater core.

Step 2

Use a knife or scissors to cut the hoses between 6 and 8 inches away from the firewall.

Step 3

Take the two hoses that are no longer attached to the firewall and connect them together with the 90 degree barbed fitting.

Step 4

Add the pipe clamps over the ends of the hoses and on the barbed fitting and tighten them.

If you start the engine and antifreeze doesn't spray everywhere you have successfully bypassed the heater core.

More Articles

article divider