Cylinder heads and Exhaust valves?

Question

What are the benefits of changing new cylinder heads and exhaust valves in the Main engine of the vessel? I am now studying a vessel which has a problem with their main engine. Frequent repair of cylinder heads (they usually weld it) and exhaust valves are the ones they do. I need to further give the benefits to be submitted to the vessel's management for them to buy new cylinder heads and exhaust valves as a replacement for the welded ones.

Answer 1

To answer your first question only, the benefits of changing cylinder heads and valves would be to improve the overall performance of the engine, like increasing its horse power, speed and fuel consumption. To prove to the vessels owner that this needs to be done, a compression test should be done on each cylinder by a mechanic. This will show how each cylinder is functioning, and the results need to be cross referenced with the compression specifications for that specific engine.

Answer 2

The only reason to change out a cylinder head is because the exhaust valves have been burnt or the valves in general have been used to a point they don't seat any longer.  Which means the engine compression to fire the cylinders on compression stokes is too low to be efficient to operate.

Or the cylinder head has a crack in it and leaks water or the compressed gasses from the engine compression blow into the water jacket through the cracks causing the coolant to blow out and the engine to overheat.

Answer 3

It sounds to me like this ship has an ongoing exhaust problem

(maybe an obstruction of the flow) Or a low volume of cooling water (look at the water pumps)

About the only reason to weld a head would be because of a crack and the most likely reason for a crack is over heating likewise the burned valves! Assuming that the engine was assembled correctly What else would cause the over heating except  one of the above!

Before you put new expensive heads and valves on this thing

check out the over heating ( just because the Gage never shows hot dose not mean that it isn't!

If the welding and the valve replacement was done correctly

then there may be no benefit at all in buying new ones a compression test would tell,but a REAL LARGE benefit in finding out WHY this would happen

especially more then ounce !