Was the heater on when you noticed the smell?
Does the heater line still have the quick disconnect fitting on the intake manifold?
I was reading elsewhere that swapping that out to a regular fitting can over pressure and kill heater cores. There were restrictions built into the original design that a frustrated previous owner may have bypassed by replacing a problematic fitting.
If that's been swapped out, maybe go back to OEM hose/connector and check the heater lines and valve for leaks as they run close to/above the passenger exhaust.
Could the residue have possibly come from the new heater core or previous contamination?
Does the heater line still have the quick disconnect fitting on the intake manifold?
I was reading elsewhere that swapping that out to a regular fitting can over pressure and kill heater cores. There were restrictions built into the original design that a frustrated previous owner may have bypassed by replacing a problematic fitting.
If that's been swapped out, maybe go back to OEM hose/connector and check the heater lines and valve for leaks as they run close to/above the passenger exhaust.
Could the residue have possibly come from the new heater core or previous contamination?