Heater Core Installation Guidelines
When installing a new replacement heater core, it is important to remember that heater core installations vary from car to car, and the following is intended only as a guide. For installation instructions that are specific for your vehicle with illustrated diagnosis and repair procedures, CLICK HERE.
The basic tools required for the typical installation of a new heater core are a screwdriver, a set of open-end wrenches and a pair of pliers. It is highly recommended that you replace your heater core hoses, hose clamps, thermostat and radiator cap.
CAUTION: NEVER REMOVE THE PRESSURE CAP WHILE THE ENGINE AND COOLANT ARE STILL HOT. ONCE THE ENGINE HAS COOLED REMOVE THE CAP SLOWLY!!
IMPORTANT!! FIND OUT THE ROOT CAUSE FOR THE HEATER CORE FAILURE BEFORE INSTALLING A NEW HEATER!
- After removing the failed heater core from the vehicle, find out why it failed: is it the original heater core? Was it replaced before? If so, how long ago? If the heater core has been replaced within the last 6 months, you may be looking at a cooling system problem, not a heater core problem. What is the condition of the coolant: color? PH? any residue in the radiator fill neck? The color should not be muddied or “rusty” in appearance. The pH should be in the range of 7.7 – 11.0. And the mix should be 50/50. Test the heater core for leaks: pin hole leaks in the core could be a sign of Electrolysis. This condition is usually a result of add on equipment – stereo amplifiers, alarm systems, plow lifts, etc. that have not been properly grounded to the vehicle. You can test for this by using a DC voltmeter to submerge the positive lead into the radiator fill neck and ground the negative lead at the battery. This should be done with the radiator cap off and the engine running. You should not read any more than 0.1 volt. Any higher reading is cause for alarm and the offending component must be found and grounded properly. Stray excessive electrical current can destroy an aluminum heat exchanger in a very short time.
- Once you have determined that the system is OK, it is strongly recommended that you flush the cooling system thoroughly and aggressively before you install the new heater core. Multiple flushings are not out of the question to assure proper system chemical balance, especially if you suspect poor coolant condition was the root cause of the previous failure. A flush machine is preferred, but flush aggressively to the best of your ability.
- Carefully re-install the heater core following the removal and additional steps listed above. Caution!! Heater pipes that are long can create destructive forces to the connection joint at the tank, if excessive force is applied to these pipes during the installation process. Be careful when inserting the heater core into the mounting housing to avoid over stressing the connection joints.
- Fill the system with a new 50/50 solution of the proper coolant and deionized or distilled water as recommended by vehicle manufacturer. Coolant pre-mixes may also be used. Be sure to replace your coolant with the same kind that was removed (refer to your owner’s manual to identify the coolant used in your vehicle). Tap water is lethal to aluminum components in a cooling system. Replace the pressure cap.
- Start engine to check for leaks. After the engine has idled long enough to open the thermostat (engine should reach it’s normal operating temperature), turn the engine off. Make sure the cooling system has cooled down before slowly removing the pressure cap to check the coolant level: add the 50/50 mix or pre-mix as needed to bring the coolant level to the bottom of the fill neck or to the appropriate level in the overflow tank. Replace the pressure cap.
- Check the coolant recovery reservoir the next few times you drive the vehicle, and, if necessary, add enough coolant mix to bring it up to the proper level.