Question

When a diesel engine is operated under a load, coolant continually comes out of the radiator overflow and there are bubbles in the radiator. Which of these is the most likely cause?

(A) Too much coolant in the cooling system
(B) A clogged radiator
(C) A stuck-open thermostat
(D) Compression leakage into the cooling system

Answer 1

(D) Compression leakage into the cooling system. The most likely cause for coolant continually coming out of the radiator overflow and bubbles in the radiator when a diesel engine is operated under a load is compression leakage into the cooling system.

Step-by-step explanation:

The most likely cause for coolant continually coming out of the radiator overflow and bubbles in the radiator when a diesel engine is operated under a load is (D) Compression leakage into the cooling system. This could be due to a faulty head gasket or cracked cylinder head, allowing the engine combustion pressure to leak into the cooling system. As a result, the pressure in the cooling system increases, causing coolant to be forced out of the overflow and bubbles to form in the radiator.