RickB wrote:Forkliftt wrote:
When then I suggest you Google THAT to get an answer. Instead of putting so much effort into making me wrong.
I I would just like an explanation from the two guys who said increasing the volume would create a knock and altering the timing will cure it.
I can't believe I am hanging in when this has gone past well meaning sharing of ideas or suggestions, but here goes.
First, I think we have different people talking about 2 different sources of knocks.
1. Mechanical wear or malfunction caused knocks such as worn wrist pins.*I*do not*consider these to be*related to injection timing.
2. That delightful Diesel knock or rattle that Cummins pickup engineers adore, Mercedes Benz engineers abhor, and trawler folk ignore. I follow the suggestion above, and quote from the font of all truth, Wikipedia (via Google):
"Knocking is more or less unavoidable in diesel engines
, where fuel is injected into highly compressed air towards the end of the compression stroke. There is a short lag between the fuel being injected and combustion starting. By this time there is already a quantity of fuel in the combustion chamber which will ignite first in areas of greater oxygen density prior to the combustion of the complete charge. This sudden increase in pressure and temperature causes the distinctive diesel 'knock' or 'clatter', some of which must be allowed for in the engine design."
My comment on timing was related to the fact that compression creates the ignition temperature, and that a lower compression ratio delays the point where this temperature is reached. Using the above Wikipedia description this would mean comparatively more fuel is already injected in the low compression cylinder when ignition starts, increasing the knock in that cylinder.
In a 3208 you can't change the timing of one cylinder alone, but to answer the question, if you could, I would try retarding the start of injection in the cylinder with the larger clearance volume.
As for troubleshooting from 1000 miles away, I have screwed up many diagnosis sitting on top of the engine. I*certainly hope that the remote response to questions without looking, hearing, or touching the engine is interpreted as ideas for the guy sitting on top to think about, not diagnosis to act on!
While Diesel engines are constructed to withstand the pressures caused by the injection of fuel into heated environments, internet forums often are not. I hope I do not cause flames or damage by injecting these comments into the heated discussion after skipperdude has graciously thanked us and moved on!