I have a Vauxhall zafira diesel 1.7 what happens if the EGR valve and inlet manifold get blocked with carbon

Question

What happens if the EGR valve and the inlet manifold get completely blocked

Answer 1

If you mean completely blocked, the car won't run. But I think you mean mostly blocked. The most noticeable effect is a loss of power.

Here is a photo that I took of my 1.9L VW TDI diesel after going too long without cleaning the intake runner and manifold. Before cleaning on the left, after cleaning on the right.

This is the intake runner just beyond the EGR valve and before the intake manifold. Even with this massive blockage, there was only a slight loss of power, no smoke, no difficulty starting and better than normal fuel consumption. No engine codes. The engine management system compensated for the restricted airflow by reducing fuel usage, which reduced engine power a little. It was most noticeable when accelerating on the highway, but not noticeable at all in city driving.

If the Vauxhall zafira diesel 1.7 has a similar engine management system, I would expect the same effect as the VW.

Answer 2

I have the same engine with about 270000KM on the clock. While I suspect that the manifold has carbon deposits, I experience no trouble there.

The EGR valve makes issues if I don't clean it regularly once a year. Sometimes it seizes in the open position, and then the engine has barely enough power to move in the first gear.

Cleaning the EGR valve is no big deal: It is located on top of the engine, easily removed and taken apart.

The only thing you need to pay attention: On disassembling, the valve is of a similar design as engine valves, there are those little keepers on a spring loaded plate, on the tip, and they can get easily lost.