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rv:diesel [2022/05/23 16:16]
princess_fluffypants [Looking forward] |
rv:diesel [2024/01/02 18:41] (current)
princess_fluffypants [Exhaust Soot] |
| ===== Applicability ===== | ===== Applicability ===== |
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| **This is not a slight against any specific manufacturer**; these problems are endemic to //all// modern diesel engines produced from the mid-2000s onward. [[https://www.dieselworldmag.com/diesel-technology/why-the-6-0l-is-so-unreliable/|Ford]], [[https://www.linkedin.com/pulse/fatal-flaw-mercedes-benz-sprinters-tom-robertson/|Mercedes]], Chevrolet, and Dodge vans all suffer from these problems. There's a few that are less bad than others, and most are pretty reliable for the first few years. But once they get over 100k miles, they all have some parts that are //guaranteed// to fail and are devastatingly expensive to repair. | **This is not a slight against any specific manufacturer**; these problems are endemic to //all// modern diesel engines produced from the mid-2000s onward. [[https://www.dieselworldmag.com/diesel-technology/why-the-6-0l-is-so-unreliable/|Ford]], [[https://www.linkedin.com/pulse/fatal-flaw-mercedes-benz-sprinters-tom-robertson/|Mercedes]], Chevrolet, and [[https://www.promasterforum.com/threads/service-def-system.50274/page-5|Dodge]] vans all suffer from these problems. There's a few that are less bad than others, but they all have the same parts that are //guaranteed// to fail and are devastatingly expensive to repair. |
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| | This article is also //not// "anti-emissions". For a very long time, diesel engines were given an unreasonable exemption from having to meet the same emission standards that applied to gasoline engines for decades, even though diesel's emissions were far more toxic than their gasoline powered cousins. In some ways, the crackdown (and current phasing out) of diesel engines from the light vehicle market was inevitable, and a welcome change from the era of smelly, black-cloud-belching vans and trucks. |
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| ==== Known Good Engines ==== | ==== Known Good Engines ==== |
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| These engines were produced before the tightened emissions regulations took effect, and are generally know for being reasonably reliable. Any engines built **after** these known good engines will be problematic. | These engines were produced before the tightened emissions regulations took effect, and are reasonably reliable. Any engines built **after** these known good engines will be problematic. |
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| * **Ford** | * **Ford** |
| * **Dodge** | * **Dodge** |
| * High Output Cummins 600 (model year 2004-2006) | * High Output Cummins 600 (model year 2004-2006) |
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| | As of 2023, pre-emission diesel vehicles over 14,000lbs GVRW [[https://jalopnik.com/pre-2010-diesel-engines-banned-from-california-roads-1850001952|cannot be registered or driven in the state of California]]. While most vans are under this limit, most box trucks or school buses will be prohibited from operating in the state. |
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| ===== Oxides of Nitrogen ===== | ===== Oxides of Nitrogen ===== |
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| Diesel engines are really bad emitters of [[https://en.wikipedia.org/wiki/NOx|NOX]], a pollutant formed when combustion temperatures go over ~2000 degrees. NOX is easy to get rid of in gasoline engines by enriching the mixture a bit and possibly add a little [[https://en.wikipedia.org/wiki/Exhaust_gas_recirculation|EGR]] to the intake, which helps lower the combustion temperatures by acting as a kind of "buffer". But enriching the mixture doesn’t help diesels, so you need a //lot// of [[https://en.wikipedia.org/wiki/Exhaust_gas_recirculation|EGR]] to bring down combustion temperatures. | Diesel engines are really bad emitters of [[https://en.wikipedia.org/wiki/NOx|NOX]], a pollutant formed when combustion temperatures go over ~2000 degrees. NOX is easy to get rid of in gasoline engines by enriching the mixture a bit and possibly adding a little [[https://en.wikipedia.org/wiki/Exhaust_gas_recirculation|EGR]] to the intake, which helps lower the combustion temperatures by acting as a kind of "buffer". But enriching the mixture doesn’t help diesels, so you need a //lot// of [[https://en.wikipedia.org/wiki/Exhaust_gas_recirculation|EGR]] to bring down combustion temperatures. |
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| Which is a problem because the diesel exhaust under full throttle is //extremely// hot, that’s why we’re having this problem to begin with. So the manufacturers need to cool the exhaust gasses that are being injected into the engine intake with a water-to-exhaust-gas cooler. | Which is a problem because the diesel exhaust under full throttle is //extremely// hot, that’s why we’re having this problem to begin with. So the manufacturers need to cool the exhaust gasses that are being injected into the engine intake with a water-to-exhaust-gas cooler. |
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| Unfortunately, trying to build a cooler that can withstand 2200 degree gasses and 200 degree coolant right next to each other has been an engineering nightmare - they are typically made of stainless steel, but over time the coolers crack and/or plug up. This is a problem with //all// modern diesel engines, on everything from little VW’s to giant semi-truck Cummins ISX engines. When they crack, they result in water squirting into the engine intake which can cause internal engine damage due to the increased pressure when coolant turns to steam. Also, it’s generally a ton of work to change the EGR cooler because of its location, especially in V8 diesels. They also plug up easily because cooling exhaust causes the soot to drop out of suspension and collect everywhere. | Unfortunately trying to build a cooler that can withstand 2,200 degree gasses and 200 degree coolant right next to each other has been an engineering nightmare - they are typically made of stainless steel, but over time the coolers inevitably crack and/or plug up. This is a problem with //all// modern diesel engines, on everything from little VW’s to giant semi-truck Cummins ISX engines. When they crack, they result in water squirting into the engine intake which can cause internal engine damage due to the increased pressure when coolant turns to steam. Also, it’s generally a ton of work to change the EGR cooler because of its location, especially in V8 diesels. They also plug up easily because cooling exhaust causes the soot to drop out of suspension and collect everywhere. |
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| Adding [[https://en.wikipedia.org/wiki/Diesel_exhaust_fluid|DEF]]/[[https://en.wikipedia.org/wiki/Selective_catalytic_reduction|SCR]] helps a lot, but using too much [[https://en.wikipedia.org/wiki/Diesel_exhaust_fluid|DEF]] is considered a bad thing because of the hassle and expense. This is one of the things that happened after [[https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal|Dieselgate]] with the VW’s - the ‘fixed’ cars now use 3 times as much [[https://en.wikipedia.org/wiki/Diesel_exhaust_fluid|DEF]]. | Adding [[https://en.wikipedia.org/wiki/Diesel_exhaust_fluid|DEF]]/[[https://en.wikipedia.org/wiki/Selective_catalytic_reduction|SCR]] helps a lot, but using too much [[https://en.wikipedia.org/wiki/Diesel_exhaust_fluid|DEF]] is considered a bad thing because of the hassle and expense. This is one of the things that happened after [[https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal|Dieselgate]] with the VW’s - the ‘fixed’ cars now use 3 times as much [[https://en.wikipedia.org/wiki/Diesel_exhaust_fluid|DEF]]. |
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| ===== Exhaust Soot ===== | ===== Exhaust Soot ===== |
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| | Diesels put out a ton of soot, this is what gave pre-emission diesel exhaust its characteristic big black clouds when under heavy load. To get rid of it, manufacturers use a particulate trap that collects the soot and uses extra-injected fuel to burn it away in a process that that can go over 2800 degrees. This works okay in vehicles that are driven hard all the time, like semi-trucks (Well the chambers eventually plug up, but it takes a while). |
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| Diesels put out a ton of soot, this is what gives diesel exhaust its characteristic big black clouds when under heavy load. To get rid of it, manufacturers use a particulate trap that collects the soot and uses extra-injected fuel to burn it away in a process that that can go over 2800 degrees. This works okay in vehicles that are driven hard all the time, like semi-trucks (Well the chambers eventually plug up, but it takes a while). | But passenger vehicles’ light duty cycles don’t allow for automatic burning, so sometimes they have to perform forced burn cycles when the vehicle is parked. This uses a ton of extra fuel and upsets the owner, who doesn’t understand why their vehicle is running at a fast idle by itself and has superheated exhaust pouring out the back. Some early light trucks actually caught their plastic rear bumpers on fire. |
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| But passenger vehicles’ light duty cycles don’t allow for automatic burning, so sometimes they have to perform forced burn cycles when the vehicle is parked. This uses a ton of extra fuel and upsets the owner, who doesn’t understand why their vehicle is running at a fast idle by itself and has superheated exhaust pouring out the back of the vehicle. Some early light trucks actually caught their plastic rear bumpers on fire. | These chambers also get plugged up easily, [[https://www.reddit.com/r/VanLife/comments/ews1r4/hit_with_the_most_intense_mechanics_bill/|which is incredibly expensive]] to fix due to the part cost and where they are located. On some light pickup trucks, replacing the chamber (sometimes referred to as the DPF, or Diesel Particulate Filter) requires lifting the entire cab off of the body and can cost a fortune due to the amount of labor involved. |
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| These chambers also get plugged up easily, [[https://www.reddit.com/r/VanLife/comments/ews1r4/hit_with_the_most_intense_mechanics_bill/|which is incredibly expensive]] to fix due to the part cost and where they are located. | To top it off, some early light diesels did a terrible job integrating the extra fuel delivery required - instead of adding an extra injector, they cheaped out and had the last injector in the engine shoot extra fuel during the exhaust stroke, which caused internal engine issues (The 6.4L V-8 used in Ford trucks was a particularly egregious example of this). |
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| To top it off, some early light diesels did a terrible job integrating the extra fuel delivery required - instead of adding an extra injector, they just cheaped out and had the last injector in the engine shoot extra fuel during the exhaust stroke, which caused internal engine issues (The 6.4L V-8 used in the [[rv:ford_e-series|Econoline van]] and Ford trucks from 2011-2015 was a particularly egregious example of this). | |
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| ===== Fuel Injection ===== | ===== Fuel Injection ===== |
| Plus new fancy variable-scroll turbos are problematic in lightly loaded applications, the vanes stick open/shut due to rust. | Plus new fancy variable-scroll turbos are problematic in lightly loaded applications, the vanes stick open/shut due to rust. |
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| On top of all these myriad issues, the Marketing departments realized that diesel engines had gotten an almost godlike mythos around them among the crowd of light-truck buyers to the point where they'd easily shell out another $5,000+ on top of the top-end gas engines for a diesel. This resulted in an escalating horsepower war between all the major manufactures (especially in the light pickup truck segment), but designing a low-revving diesel to make a ton of horsepower makes materials/construction of the engine itself very very expensive to initially build. | On top of this myriad of issues, the Marketing departments realized that diesel engines had gotten an almost godlike mythos around them among the crowd of light-truck buyers to the point where they'd easily shell out another $5,000+ on top of the top-end gas engines for a diesel. This resulted in an escalating horsepower war between all the major manufactures (especially in the light pickup truck segment), but designing a low-revving diesel to make a ton of horsepower makes materials/construction of the engine itself very very expensive to initially build. |
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| ===== Looking forward ===== | ===== Looking forward ===== |
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| Over time as manufactures have figured out what works/doesn't work, diesels have gotten slightly less bad than the first iterations of emissions-complaint engines. And for situations where they are run hard with severe duty cycles, diesel still offers a significant advantage in usable power and fuel economy. However for light-duty cycles such as seen in vans and consumer-oriented trucks, we can expect to see manufacturers realizing that diesels no longer make sense outside of perhaps the largest 1+ ton trucks. This is exemplified by Ford completely dropping the diesel option for the Transit in the US market for the 2022 model year. | Over time as manufactures have figured out what works/doesn't work, diesels have gotten slightly less bad than the first iterations of emissions-complaint engines. And for situations where they are run hard with severe duty cycles, diesel still offers a significant advantage in usable power and fuel economy. |
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| | However for light-duty cycles such as seen in vans and consumer-oriented trucks, we can expect to see manufacturers realizing that diesels no longer make sense outside of perhaps the largest 1+ ton trucks. This is exemplified by Ford completely dropping the diesel option for the both the F-150 and the Transit in the US market for the 2022 model year. |
