Question

physical damage to a catalytic converter can occur under all of the following conditions except:
a. when a large rock strikes the converter.
b. due to a thermal shock.
c. when the hot convertor suddenly comes into contact with cold water in a deep pothole.
d. when the catalyst is coated by silicone from improper sealants.

Explanation:

• Option a: A large rock striking the converter is a physical impact that can cause physical damage.
• Option b: Thermal shock (sudden temperature change) can lead to physical damage like cracking in the converter structure.
• Option c: Hot converter suddenly contacting cold water (thermal shock - type situation) can cause physical damage due to differential expansion/contraction.
• Option d: When the catalyst is coated by silicone from improper sealants, it is a chemical poisoning (contamination) of the catalyst, not a physical damage to the converter's structure.

Answer:

d. When the catalyst is coated by silicone from improper sealants.