Diesel particulate filter or catalytic converter

Lamont in NC · Jul 30, 2015

Seems it used to be diesel engines didn't have emission controls and I was told despite the smoke their emissions were not as bad for the environment as gas engines. Now days they require DEF fluid and the scrap yard guy just told me they have catalytic converters--like on gas cars. Really? Is a diesel catalytic converter the same as a particulate filter? A guy I was talking to the other day mentioned he'd removed it from his diesel pickup.

Is this stuff required on diesel vehicles (pickup, heavy trucks, off road equipment)? Frequently used?

I'm just looking to better understand the whole situation. The only diesel I own is a 1988 compact tractor which has no emission controls and I'm not in the market for another vehicle of any kind. I'm just curious.

mj · Jul 30, 2015

Catalytic converters and diesel particulate filters are 2 different things - The DPF was added to meet ever stricter EPA rules in 2008??? or thereabouts. Off-road equipment slid by until a couple of years ago, now they have to meet 'Tier 4' requirements. I have a 2009 diesel tractor that has no emission 'controls' that I've found - what the future holds depends on who gets the presidency in 2016 and what he or she does to reign in the 'enviro Nazis'.

jeffcat · Jul 30, 2015

You anin't gonna believe this one. My neighbor needs a couple of diesel engines for small equipment. His older ones were Yanmar and worked great. Right now he can't get any new ones cause they are not building them to teir 4 standards! Can you imagine a single cylinder diesel engine that you need to pour cow wee into?

MSM · Jul 30, 2015

Pretty much any diesel engine over I believe 25 HP is now required to meet Tier 4 specs,whether it is done with diesel particulate filters(DPF),diesel exhaust fluid (DEF) catalytic converters or multiple turbo chargers, with exhaust scrubbers. Caterpillar got out of the over the road truck engine business because of this, but now their new off road equipment requires DEF and a particulate filter along with the fluid heaters,multiple sensors,dedicated control modules and special startup and shut down procedures,which if not followed, electronically notify Caterpillar,who in turn notify the equipment owner or lease holder. Multiple procedural errors can be grounds for no warranty coverage on the affected systems. A new exhaust filter for a 950 wheel loader is about $10,000 parts and labor,so it pays to follow the necessary procedures,for startup and shutdown,regen and maintenance

jimg.allentown · Jul 30, 2015

A particulate filter is just that - a filter. Traps the little particles that a diesel emits otherwise known as soot.

A catalytic converter is a device that somehow modifies a chemical reaction without itself becoming part of that reaction. In this case, it either completes combustion by breaking down unburned fuel (HC) or breaks down oxides of nitrogen (NOx).
Diesels are comparatively cleaner than gas engines in terms of CO and HC emissions, but higher on NOx emissions due to higher combustion chamber temperatures. BUT, diesels also emit a significant amount of particulate matter - mostly soot.
Now, with the tier 4 requirements, there are a lot more emission controls on diesels.

BTW, just because you cannot see them, there are still emission controls on many seemingly uncontrolled engines. Among them are camshaft profile, injector spray patterns, injection pump timing profile, and a few others I may have forgotten. These controls are built into an engine from day one, and are not visible as an "emission device" as we think of it.

MarkB_MI · Jul 31, 2015

In the early days of emission controls, particulate emissions weren't considered to be such a problem as nitrous oxides, unburned hydrocarbons and carbon monoxide. So diesel engines were considered to be "cleaner", even though they put out massive amounts of particulate emissions. Once emissions from gasoline engines were more or less under control, particulate emissions came under scrutiny, so that diesels were no longer "clean".

Diesel particulate filter or catalytic converter

Lamont in NC

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mj

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jeffcat

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MSM

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jimg.allentown

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MarkB_MI

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