Motoring myths do they still ring true

[figbat]

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]

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 !

 

[Ming the Merciless]

By what mechanism does Redex clear a DPF?

It works, you tell me how redex dpf cleaner does it.

 

[fossyant]

It works, you tell me how redex dpf cleaner does it.

He better ask Google AI !

 

[Drago]

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.

Thats where Im skeptical of this stuff. Anything downstream of the combustion process is immune to these additives, which have been stripped to their molecular constituents but he heat and pressure.

 

[figbat]

He better ask Google AI !

Every word of my reply was from my own experience and knowledge of engines and chemistry.

I’ve done some research and it looks like under some circumstances the Redex DPF cleaner could catalyse the passive regeneration process and help reduce soot loading. However the very species that do the catalysing will also accumulate as additional ash in the DPF. Swings and roundabouts.

Of course this only applies to the Redex DPF cleaner, not to run-of-the mill “Redex”.

 

[biggs682]

Is it not a petrol, or is it an older DCi ?

Petrol

 

[Drago]

Every word of my reply was from my own experience and knowledge of engines and chemistry.

I’ve done some research and it looks like under some circumstances the Redex DPF cleaner could catalyse the passive regeneration process and help reduce soot loading. However the very species that do the catalysing will also accumulate as additional ash in the DPF. Swings and roundabouts.

Of course this only applies to the Redex DPF cleaner, not to run-of-the mill “Redex”.

Some additives, allegedly, assist with raising the combustion temperatures during the regen process.