Rick
November 27, 2013, 2:01pm
21
Beelzebubba:
Diesel engines are more durable than typical gas engines because they must be able to endure much greater compression levels and internal pressure. Combustion in a gasoline engine is achieved by squirting a precise mixture of gas and air into each cylinder, then a spark plug generates a spark to ignite the fuel/air mixture. That small explosion is what forces the piston to move up and down in within the cylinders.
Instead of using a spark for combustion, diesel engines rely on the heat generated by much higher levels of compression to ignite and burn their fuel. They don’t have spark plugs. But the engine also must be capable of handling the high compression levels, which is why diesel engines have historically been very durable and longer-lived that their gasoline counterparts.
But there are some other cold start issues to consider that are fairly unique to diesels. One is that diesel fuel starts to congeal below 40 degrees Fahrenheit and it doesn’t combust well (or at all) in jelly form! As recently as the mid 80s, most diesel engines had “glow plugs” in he fuel tank to heat the diesel fuel on cold days. You would turn the ignition key forward to the ‘Run’ position (but not all the way to ‘Start’) and a light on the dash would come on indicating that the glow plugs were warming the fuel. When that light went off, you could go ahead and turn the key to Start and start the engine.
The vast majority of diesel engines used in cars over the last 20+ years have been turbocharged. Diesels inherently make their power at low engine speeds but they do not rev as quickly or nearly as high as gas engines. A diesel may ‘redline’ at 4000rpm while many gas engines can rev to 6500rpm or beyond. The problem is that diesels are good at getting things moving from a stop, but acceleration is generally much slower than a regular gas engine. In the early 80s, an Oldsmobile Cutlass Supreme with a 350 V8 Diesel took more than 18 seconds to hit 60mph. The same car with a smaller 307 V8 gas engine could do the same in about 12 seconds.
The solution to improving diesel performance to the level of similarly sized gas engines is to add a turbocharger. In the simplest terms, turbochargers are usually made from ceramic and they force a much greater amount of fuel/air mixture into the combustion chamber so the engine generates more power. Ceramic turbochargers operate at extremely high temperatures and they do NOT respond well to operating at sub-freezing temps until they have a few minutes to reach a normal operating temperature. Many new turbocharged vehicles, gas and diesel, have their engine control modules programmed so that the turbocharger will not operate until the engine reaches normal operating temp.
I said all of that to say this- because of their “overbuilt” design and construction and generally lower engine speeds, diesels are less susceptible to cold-start wear than gas engines. BUT they are still susceptible to some degree of cold-start wear and letting them warm up after starting or driving them very gently until the engine temp reaches normal levels will extend the longevity of the engine, gas or diesel!
Two nits. Glow plugs are installed in the engine combustion chamber ( or pre combustion chamber) not the fuel tank