I just discovered what seems to be anti-freeze saturating the passenger-side carpet of my S-10 pickup. Where could it be coming from? How can this be repaired?

Lorna Jacks, Gilroy, Calif.

Yuck! I hate it when this happens. Your pickup’s heater core has sprung a leak. It is allowing engine coolant to seep into the cab, and is making a mess of the carpet and insulation below.

The heating system uses a pair of coolant hoses and the heater core to transfer the heat of the engine to the cab. The heater core, about the size of a cigar box, is located deep within the instrument panel, and contains a labyrinth of passages and fins. The ventilation system blows air through the heater core and on to the designated heater or defroster outlet.

Your first priority is to check the radiator coolant level before driving the truck further. When coolant leakage occurs, the system might not be able to recover coolant from the overflow tank during engine cool-down, resulting in a misleadingly adequate overflow tank fluid level and a low radiator/engine level. Be sure to remove the radiator cap only when the engine is cold to prevent the chance of dangerous hot fluid and/or steam escaping. It’s OK to refill the system with water, as it will be drained and refilled at the time of repair.

Priority two is to pull back the passenger-side carpet as far as possible to prevent further saturation and to begin the drying process. Depending on the amount of intrusion, it might be necessary to remove the kick-panel trim or door-sill trim plate to gain full access to the wet area. Coolant is slimy stuff and doesn’t rapidly evaporate. With the car parked, work the area thoroughly with a hair dryer, then with a fan. This should do the trick, saving you some dollars at the repair shop. If the insulating pad beneath the carpet is badly saturated, I’d cut out the largest section possible, dry it in the sun for a week or two, then reinstall it later.

Renewing a heater core can be a miserable job, requiring two to 12 hours’ labor, depending on the vehicle. Fixing it might run from $100 to several hundred dollars. Pickup trucks without air conditioning are generally the easiest, and luxury cars the worst. It’s important to flush the cooling system of all remaining coolant and any particulate matter as corrosion and erosion are the leading cause of heater core failure. It’s also wise to renew the heater core’s hoses at this time, as the unit’s fragile fittings can be easily damaged during hose removal.

If time or resources hold you back from an immediate repair, a radiator stop-leak product can provide temporary relief – perhaps for a week to several months.

Be sure to bundle an old towel beneath the heater box, at the top edge of the carpet, to catch any additional leakage.

Brad Bergholdt teaches automotive technology at Evergreen Valley College in San Jose, Calif.



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AP-NY-07-29-05 0613EDT