Motoring myths do they still ring true

Page may contain affiliate links. Please see terms for details.

figbat

Former slippery scientist
  1. DPF clogs up.
  2. Bit of redex and clears up.

By what mechanism does Redex clear a DPF?

DPFs block up in two ways:

(1) filling up with soot from the incomplete combustion of fuel. This is what they are designed to trap. Soot is carboniferous and so can be cleared from a DPF through heat - get the DPF hot and it burns away the soot. DPFs can be heated up passively or actively according to how the engine is running. The ECU monitors the pressure drop across the DPF and when needed will trigger an active regen session. Passive regen happens when using the engine hard, increasing exhaust temperatures.

(2) filling up with ash - a residue of the combustion of engine oil. Engine oil contains metallic elements which, when burnt, become metallic oxides (ash). You can’t clear ash by heating the DPF up because ash doesn’t burn. You can only clear it through mechanical or chemical cleaning. The chemicals needed to dissolve the ash are fairly potent and won’t survive coming through the engine combustion process, certainly not at the levels added to a tank of fuel.
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
I suspect it doesn't suddenly clear it, but will raise combustion temperatures sooner - diesel engines take an age to warm up - if I commute to work, in winter, it might just be upto temperature after an hour of traffic - that's what kills them.

A severely clogged DFP can't be 'fixed' but I suspect a little preventative intervention (additives or being aware of the need to get diesels up to temperature to clean the DPF) is the best course of action, but folk don't do this - why would they, a vehicle is like white goods, get in drive, done !
 
Top Bottom