Grand Scenic needs 'filter blowing through once a month'

If (a) it's a diesel, and (b) the [something or other] filter is a particulate filter, then the dealer is absolutely correct.

What your friend may have not been told is that failure to give it a bit of a thrash regularly will seriously hurt his wallet!

Chris

Ok thanks, Chris. I take your word on that, but surely the whole point of a particulate filter is to catch particulates? But presumably by giving the engine a good blast now and again it in fact blows the particulates *through* the filter, thus rather negating its effect ?

Any idea what it roughly costs to have a garage change the p. filter ? I guess it would normally be changed as part of a routine service (if the filter survives that long) ?

An hour at 60mph seems a bit excessive. I would have thought 60mph for 15mins would have much the same effect ?

Presumably if the filter clogs up then engine performance is reduced ?

Cheers, Jeff

No it gets it hot so that it burns them up.

Not normally, they're expensive

It depends :-) If it spends its life driving slowly round town then it'll need a real trip down the motorway.

The particulate filter is just that. It cathes the particulates from the exhaust, but it needs a long run to clean itself. If it never gets a long run, then it'll eventually choke up, leading to reduced performance, and a trip to a garage to get a re-gen run, or if bad enough, a new particluate filter fitted.

During a long run, once the ECU has decided the engine has been run for long enough, it starts to inject fuel at the end of comustion, which gets dumped out the exhaust port. When it reaches the particulate filter, it burns up causing the filter to heat up and burn of the particulates, essentially cleaning it.

Jeff (j_e_f_f_d_a_y snipped-for-privacy@daylightit.co.uk) gurgled happily, sounding much like they were saying :

No, it raises the temperature in the exhaust sufficiently to burn the captured particulates off at a high enough temperature that they're not a pollutant.

No.

FFS, is an hour at a gentlish cruise *really* that big a deal? It's not exactly the dark side of the moon and back.

Thanks, Guys, for your various responses.

Some useful info there. I understand how it works now...makes sense.

I'll convey the essence of this back to my friend and get her to give it a good long blast every now & again.

Cheers :0)

Jeff (j_e_f_f_d_a_y snipped-for-privacy@daylightit.co.uk) gurgled happily, sounding much like they were saying :

An hour at 60 isn't a "good long blast"... It's a gentlish cruise, ffs.

Three or four hours at 90'd be a decent blast.

This will be the particulate filter which needs certain operating conditions for the ECU controlled burn-off to occur- this is when extra fuel is injected late into the power stroke which raises exhaust temperature significantly over normal to allow the filter to burn up the accumulated soot.

These filters need replacing at around 80K or so miles (72 in some pugs) and are not cheap. I would not advise anyone to buy the Euro 4 rated diesels that are near this mileage for this reason.

Tim..

through the [something or other] filter through, otherwise you

Tom Burton ( snipped-for-privacy@freezingcoldmail.com) gurgled happily, sounding much like they were saying :

Wikipedia gets a load of stick - but there's some excellent articles on there, and that's one of 'em...

Funnily enough I've just been reading it !