Question

While inspecting the intake manifold from a v-type engine, a tech notices a crack in the exhaust gas crossover passage on the underside of the manifold. the most likely cause of this condition is

-the intake manifold bolts were overtorqued
-the intake manifold bolts were not torqued in the correct sequence
-the EGR passage in the manifold is plugged with carbon
-the heat riser valve on one of the exhaust manifolds is stuck shut

Answer 1

The heat riser valve on one of the exhaust manifolds being stuck shut is the most likely cause of a crack in the exhaust gas crossover passage on the underside of the intake manifold in a V-type engine.

Step-by-step explanation:

The most likely cause of a crack in the exhaust gas crossover passage on the underside of the intake manifold in a V-type engine is the heat riser valve on one of the exhaust manifolds being stuck shut. The heat riser valve is responsible for controlling the flow of exhaust gases to the intake manifold. When the valve is stuck shut, it can cause excessive heat buildup in the crossover passage, leading to a crack.

Intake manifold bolts being overtorqued or not torqued in the correct sequence can cause other issues such as warping or leaks, but they are not the most likely cause of a crack in the exhaust gas crossover passage.

A plugged EGR passage in the manifold can also cause problems, but it is not the most likely cause of a crack in the crossover passage.