flash7210 wrote:
TURBO-DIESEL-FREAK wrote:
geordi wrote:
I have never claimed to be any kind of vehicle technician. I am not specially trained in theory of engine design, and I think you will find very few technicians are trained in WHY something is done because that is not germane to their job. Diagnostics and repair are.
I think Flash has the right answer: These are not designed to rotate. The cleaning of the seats is obviously not that important on modern engines. As far as binding in the guides, that is a huge potential issue but I have not seen any evidence thus far for that - all the failures have been below the valve guides entirely. Not a bad guess - and if they weren't oiled, I can see the valve guide wear being a huge issue, but I don't think it is the case on this engine.
Sorry geordi, but knowledge of the fundamentals of engine design and why things are designed in a particular way they are an important part of a real technician's training. It is also an important part of a technician's ability to diagnose a problem. Otherwise you end up with people who think they know better how to repair and upgrade an engine's operation than the actual people who designed the engine, such as yourself.
A little bit quick to judge dont you think?
Very few automotive and diesel technicians and machinists know all the intricacies of the valve train.
A degree in mechanical engineering is not a requirement for being a technician.
And given the various designs Ive seen over the years, its obvious that the engineers never had to turn a wrench for a living.
Actually, NO, I am not being too quick to judge here. I never said a technician requires the same level of training that an engineer has, but that he or she should at least have training in the fundamentals of automotive design. It is not necessary to know EVERYTHING about a valve train, but some education is necessary. I do not know what the level of training is required in the U.S., but I was taught the fundamentals in high school automotives courses.
geordi was asking why valves rotate. This is most certainly not a question that requires a mechanical engineer to answer, and I learned why they rotate back in high school in the early 1980s.
As for dumping on automotive engineers, you are wrong here as well. It is almost always the case where flaws in automotive design are directly the cause of the bean counters the manufacturers employ to maximize profits, or designs are altered from what is best to what suits the government bureaucrats by political fiat, (EPA regulations, safety regulations and such).
With geordi, you have someone who has the skill to repair a blown CRD engine cylinder head, but not the background knowledge to know why things are happening. His general inquiry asking about why valves rotate is proof of that. In fact, this entire thread is going in the wrong direction because geordi refuses to consider the undisputed fact that the number 1 cause of cylinder head failures and related problems in internal combustion engines are cooling system failures, and instead focuses on a somewhat dubious notion that the torque-to-yield bolts are at fault here. Re-visit the first page of this thread to see for yourself; he blew me off rudely when I suggested he include driving habits, cooling system issues and modifications. This is now not surprising to me, as he has posted more than once that he does not believe that blocking off the cooling system bypass circuit is a big deal, and that he has a "theory" that other cooling system circuits will take over the task of circulating the engine coolant adequately during warm-up.
So, despite the fact that geordi has made no claims to being a technician of any kind, he has "theories" about how the R428 should operate. He believes - essentially - that he knows more than the engineers who designed this engine. This shows a rather blatant display of ignorance AND arrogance, all at the same time.
Cylinder head gasket failures and valve failures seem to be an affliction of the North American CRD engine, yet problems are much less prevalent in CRD engines in other markets around the world. Someone has to ask why, and investigate for themselves. Has anyone even bothered to ask V.M. Motori if the R428 engine is produced in more than one manufacturing facility, and if they have had problems with their valves in other markets? Somehow I doubt this.
I do not believe this thread will ever go anywhere until those members here who are interested in getting some results consider ALL of the possibilities of why there is a prevalence of cylinder head gasket issues and valve failures in North American R428 engines.