Thursday, Aug 24, 2017 at 16:32
If you do some 'net searching and asking others who own vehicles fitted with a DPF, you will find these recurring and nagging issues ....
1. DPF's increase fuel consumption - by at least 3%. This is not denied, even by the manufacturers.
DPF's are a restriction to exhaust flow, and they regularly need additional diesel injected into the engine, or into the DPF, to burn off the collected soot.
This burnoff is required to be carried out every 300-800kms, depending on the make and model.
2. Because the DPF restricts exhaust gas flow, they reduce HP/KW output.
3. The DPF burnoff/regeneration cycle requires speed and heat input into the DPF. Ford state a minimum burnoff/regeneration speed of 30-40kmh, Mitsubishi say 40kmh, for Holdens, it's 50kmh.
Toyota are the only ones who have a burnoff/regeneration process that can be done at idle.
For those carrying out constant slow-speed driving - such as on bush tracks, on stop-start heavy traffic conditions, and paddock driving, such as rounding up stock - this requirement for regular speed for burnoff/regeneration is a right PIA.
4. The DPF is not designed to last the life of the engine. In general, the lifespan of a DPF appears to range between 120,000 and 200,000kms.
Most diesel engines will easily reach 350,000-400,000 kms before overhaul is needed.
So you will need to replace the DPF at least once before engine overhaul is needed.
The DPF is a very costly item, with quoted replacement prices ranging from $2500-$5000.
5. There are companies who specialise in DPF removal. This can be carried out so neatly, you don't know it's been done.
If you buy a late model used diesel vehicle, and you don't know it has had its DPF removed - and you get checked out for emission/exhaust smoke levels - and then get a yellow sticker because the DPF is found to be missing, you're up for the substantial additional cost of a new DPF installation, on top of your used vehicle purchase cost.
6. It's not uncommon for a requirement for a workshop DPF regeneration to be carried out, because of a lack of owner knowledge and procedures.
Fully three-quarters of the car owners in this world never
check under the bonnet, let alone read up on, and learn about "proper", or involved, DPF burnoff/regeneration requirements and processes.
DPF's also need regular workshop regeneration, because they become clogged with crankcase oil residues, that come from oil being burnt as it passes the rings.
You can guarantee that workshop regeneration of DPF's is a money-spinner for workshops and dealers, they are pretty good at ripping off owners at the best of times, so you can imagine how they will make money out of unnecessary DPF replacements or unnecessary regeneration jobs.
7. DPF's are a major fire risk in dry grass, stubble or spinifex. They need to reach 600 degs C for burnoff/regeneration to occur - this is nearly double most regular exhaust system component temperatures, and there are many warnings by authorities about the need to watch for fires caused by DPF's.
You could possibly initiate a fire with a DPF on a hot Summers day, simply by pulling off the highway into some long grass, to allow a wide load to pass.
How DPF's work
Cheers, Ron.
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