Re: Re: Re: Re: super m diesel

Posted by G-MAN on August 27, 2002 at 16:09:50 from (206.106.139.74):

In Reply to: Re: Re: Re: super m diesel posted by Steven@nd on August 27, 2002 at 13:00:56:

I'm not trying to start an argument of stir anything up, but I wanted to take issue with a couple things you said. It is generally acknowledged that Caterpillar was the first manufacturer to have a diesel engine farm tractor - the Diesel 60 introduced in 1931. These machines obviously weren't nearly as popular as the Farmalls you mention, but they were the first and were used pretty extensively for farming on the west coast. The second thing I noticed was your prediction that a new diesel would definitely crack the head if shut off hot. I'm a JD tech and of course I know that it is absolutely the worst thing to do to an engine, shutting it off hot, but you will rarely, if ever, damage it to the extent of a cracked head. Most heads are cracked during engine operation, when the engine is being overloaded and the cooling system absolutely is at it's limit and simply cannot remove any more heat or the cooling system loses it's coolant, which obviously is going to lead to a severly overheated engine. In a hot shut-off situation, coolant will continue to absorb heat after shut-off and the head may actually be hotter than it was while running, due to no airflow through it. This will hold true as long as the engine was not overheated at the time it was shut down. Unless you plan on running the engine at idle until you see the engine temp come down substantially - which can take 15 minutes or more, you aren't going to see huge differences in the head temperature. The metallurgy, engineering and manufacturing processes used in today's engines are also light-years ahead of where they were 50 years ago, which also allows newer engines to survive conditions that would have put older iron on the scrap heap. We have many center pivots in our area running diesels as power-units. Most are set up with safeties to prevent damage if something goes wrong, where the pivot panel will actually shut down the engine when it is running at full load. This happens somewhat frequently given the number of pivots around, and if the heads were liable to crack, we would be replacing them all summer long. I've also seen tractors pulling full load on the dyno run out of fuel, because techs didn't check it before they started, or misjudged how long the fuel would last. What is much more likely in this situation and the power unit situation I mentioned is valve damage due to warping, which occurs when the red-hot valve stops in a position off it's seat and can't release it's heat into the seat, head and eventually the cooling system. If this were to happen to me, I would be much more likely to turn the engine over a few revolutions ever couple seconds for five or ten minutes to cool the valves while somebody else went for fuel, than to worry about the head cracking. Cooling off an engine after full-load operation is also necessary to cool the turbocharger and prevent oil coking in the bearings after shut-down. Like I said, I'm not trying to start a fight or anything, I just wanted to post what my experience has been.

Follow Ups:

• Re: Re: Re: Re: Re: super m diesel Steven@nd 10:16:25 08/28/02 (1)
  • Re: Re: Re: Re: Re: Re: super m diesel G-MAN 10:50:20 08/28/02 (0)

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