Heater Channel Rot
Symptoms
The sills (rocker panels) that run along each side of the car are actually heater channels, hollow box sections that carry warm air from the engine compartment to the cabin. They corrode from the inside out, and by the time you see external rust, the structural integrity is already compromised.
Cause
Warm, moist air from the engine-driven heater system condenses inside the channels. Drain holes block with debris. The channels rot from inside, hidden from view by external trim and undercoating.
Fix
Replacement heater channels are available as reproduction parts.
Fitting is major surgery, the car essentially needs to be separated at the sills, the old channels cut out, and new ones welded in with precise alignment.
This is the most significant body repair on a 356.
Cost: $10,000-$25,000 per side at a specialist body shop.
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