Whirring... Fan?

[MarkBeatty72]

Just done a 8 mile round trip and when I pulled onto the drive and turned the ignition off and there is a noticeable loud whirring; possible fan noise which lasted for a good 3-4 minutes. I also noticed during that run that the start/stop didn't kick in either despite the car temp being up to temperature etc...

I did a couple of hard acceleration in stretches but nothing that the car can't handle.

Any ideas guys?

 

[Buzzlightyear]

I guess that'll be a dpf regen in progress when you got home. Quite disconcerting first time it happens.

 

[marty_34]

dpf regen, if revs sat on 1k revs and stop start doesn't happen that will be why for sure

if you check il temp when happens you might find oil temp is u around 100 c

 

[MarkBeatty72]

So are we saying this ok and quite normal. Not clued up on this DPF stuff. Had other diesels in the past: vauxhall and ford and never noticed this. The Leon's only done just over 500 miles, am I worrying about nothing?

 

[Buzzlightyear]

am I worrying about nothing?

Yep.

 

[Ant]

Every now and again, the engine will try to raise the exhaust temperature to burn off soot collecting in the DPF, particularly if you've been doing lots of short journeys. If you interrupt this process, the fan will continue running to cool the engine bay which will be hotter than usual. An 8 mile journey won't be long enough to reach and maintain the exhaust temperature for long enough, hence why you noticed it.

Back when mine was new, there was also a horrible 'hot engine' smell that accompanied it each time, but this is less noticeable now... This process happens about once a fortnight for me, but will be dependent on usage and driving style. Nothing to worry about, unless you start getting warning lights when the soot reaches higher levels and the regens can't clear it.

 

[MarkBeatty72]

Ant,
Yes that hot engine smell was there also...
Thanks for the reassurance guys! Appreciated

 

[marty_34]

the smells a dead giveaway like

 

[Suicida1 Zombie]

I personally love the smells that come from my car when I get out of it after hammering it for a while AND its been doing a DPF regen - Hot brakes, Hot exhaust, Hot Oil. It smells like fun LOL

 

[EoinM]

The main dealer technician told me when I got mine serviced that flooring it all the way can start a regen if the filter is over a certain percentage full. I gun it on the motorway on ramp if I know I'll be on it a while to facilitate it now as a result.


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[MarkBeatty72]

Had a DPF regen again today. How frequent should they be, what are the factors. Bearing in mind I've it had it 2.5 weeks and it's only done 600 miles of which 420 miles are a short commute to work and short distances at the weekends. Had definitely 3 regens, two in the last couple of days hence this thread starting.


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[marty_34]

might be an idea to give the car a good run out somewhere, you need to get the engine warmed up and then keep the revs to 2k while it regens. good 10-15 mins down motorway once regen starts will do the trick

 

[chrisRibiza]

Short journeys and dpf's are not a good mix.

Would have been better getting a petrol if your only doing short journeys.
I was told by the dealer id need to be doing a min of 18k miles per yr before considering a diesel.

 

[Ant]

The main factor causing the regens is the soot content in the DPF which reduces its' efficiency - usually worsened by lots of cold starts and short journeys that don't allow enough time at the optimum temperature to clear it passively. The car's action to initiate an active regen raises the exhaust temperature to a higher than normal level which accelerates the regen process whilst the conditions are suitable.

To help it along, as the others have said, try regularly driving in a way that keeps the exhaust hot. Whenever you take your foot off the pedal, it will start cooling and slow the regen process, hence why a steady motorway drive usually helps. If mine is being particularly bad, I'll sometimes run in a gear lower than usual to help keep the exhaust gas temperature high.

The frequency of regens can vary a lot. My first regen was the morning after collecting it from the dealership, with no more than 40 miles on the clock. Nowadays it is noticeable every 1-2 weeks, although after a long motorway journey (100+ miles), it might then go for 3-4 weeks without any regens.

If you've had two in close succession, this could indicate that the first one wasn't able to run for long enough to make much difference, so it restarted as soon as conditions were suitable again.

 

[MarkBeatty72]

Ant
Thanks for the clear explanation. Fortunately we're going to Scotland on Saturday for the week so will be doing easily over 1000 miles - country roads and motorway driving - so hopefully this will help

 

[Ant]

Yeah, the longer drives should help it a lot. You might find that as the engine gets a few miles on it, it will run more efficiently and require fewer active regens. My fuel economy improved significantly after the 5,000 mile mark, and I'm also noticing fewer regens than when it was new. It's still very early days if you're only at 600 miles.

 

[JK1]

I don't really understand the regens. I was under the impression if I drove a lot of miles it would stay clear and it was only under short journeys that it would require regen.

A couple of months ago I drove nearly 300 motorway miles in a single trip. Parked the car, 2 days later I take a 10 mile journey and it's doing a regen. Surely the 300 miles should have passively cleaned it anyway?

 

[Itspaul]

With the dpf what is considered a short journey ? That car has a 15 each way mile commute each day is this enough to keep it clean ? The commute is a rural trip so no noticeable traffic

 

[JK1]

You might find in the winter you'll arrive home mid-regen. My 12 mile commute, I sometimes find it mid-regen, even in the summer.

 

[Ant]

I would consider a short journey as less than 15-20 miles, with less than 50% on a motorway/dual carriageway. My daily commute is 25 miles each way with about 15 of those on the motorway, which still gives regular active regens. Annual mileage is around 12,000 - any less than this and I would've considered going down the petrol route instead.

JK1 - My coolant doesn't reach running temperature for 3-4 miles. In my opinion, a 12 mile commute isn't enough to heat the exhaust to regen temperatures for long enough to make much difference, unless you're doing occasional longer drives.