Re: Diesel engines for beginners

Posted by G-MAN on December 26, 2002 at 15:49:04 from (206.106.139.74):

In Reply to: Diesel engines for beginners posted by Will Henry on December 26, 2002 at 15:18:18:

Will, each fuel type has it's own pros and cons. Diesels are generally more efficient, last longer and produce better low-end power. However, they are generally heavier, harder to start in cold weather and more expensive to repair. Gasoline engines need 4 things to run - fuel, air, compression and spark. Diesels basically have one less system than a spark-ignition engine, which is the ignition system. Anyone that's been around old tractors knows that sooner or later you're going to have ignition problems - be it a bad coil, points, plugs or whatever. Diesels fire by injecting the fuel into the combustion chamber when the piston is at or near the top of the compression stroke. The hot air (from being compressed to a fraction of it's original volume) ignites the atomized fuel so you don't need a spark. But, rebuilding an injection pump and/or nozzles is much more expensive and time consuming than replacing points or plugs. To ignite the fuel diesels run much higher compression ratios than spark-ignition engines, which is part of the reason they are harder to start when it's cold. It's much harder to push a piston up against a 16:1 compression ratio than up against a 8:1 compression ratio, so diesels usually have more batteries, stronger starters and such which can lead to more $$$$$$. The fact that they need hot air in the cylinder to fire also hurts cold-weather starting, as the compression may not be sufficient to heat very cold air up enough to fire the cylinder. That's why many diesels have glow plugs or intake heaters - to heat the combustion chamber or intake air and make it easier to start. Providing the fuel system, cranking system and compression are up to par, most diesels will start pretty reliably down to around 30 degrees or so. Some are more cold-blooded and some are less, and a block heater, oil heater or some other device to warm up the engine will make them much easier to start in cold weather. In sub-zero temps, even a lot of gas-burners won't start without a block heater, so that's kind of a wash. As far as the respective values of each type, that is going to depend on the specific brand and model of tractor, the seller and buyer and so forth. One tractor could be a steal at $3000, while another could be way overpriced at that level. Diesels are generally more expensive to purchase though. My advice to you is that if you're planning to work on your tractor yourself, start with a gas-burner, as parts will be cheaper and maybe easier to find. As you gain experience working on that one, you can move up to a diesel. And if you're using the tractor as a hobby machine or something similar, the savings in fuel between a gas and a diesel probably won't be enough to justify the extra costs for service and repair on the diesel.

Follow Ups:

• Re: Re: Diesel engines for beginners Tom 16:22:29 12/26/02 (1)
  • Re: Re: Re: Diesel engines for beginners TAB 15:22:37 12/27/02 (0)
• Re: Re: Diesel engines for beginners Will 16:21:12 12/26/02 (0)

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