Should I be worried about buying a diesel with dpf?

Apples2

6K miles per annum - forget a diesel.

I have a 530D complete with the wonderful DPF. I had a Saab before this..... take the BMW!!

Key to this engine is the coolant temp. A weakpoint are the thermostats, 2 to speak of, the main stat and the EGR stat. They have a habit of failing after about 70k miles.
The stats stick open so you always have coolant racing through the radiator, this in turn, prevents the engine getting to a suitable temperature to enable a DPF regen. It will run in the high 60's, low 70's.

a DPF Regen will not occur below 75 degrees. With working stats you will get to a running temp of about 93 as can be seen in one of my records. You can see a slight dip at 88 degrees when the stats open.



If you are buying, ensure you check the running temps. New stats are about £80 for both. Fitting is simple for the EGR stat, the main stat is more difficult but simple enough for a home mechanic.

Glowplug errors will also prevent a regen. It's a mystery how many failed will cause problems but in my experience, errors on 4 or more will cause problems (the car will start and run fine with all 6 in error).

It would be ideal to use a C110 scanner to check for DPF Backpressure as it is an easy plug in and check.
Much better would be to plug a laptop in and run a backpressure test.



I've always considered pots of magic complete snake oil but I did put a bottle of this in mine and re-ran the test after the tankful had been used up and got this






In all seriousness, after owning a Saab and a 3.0 BMW, take the BMW.... just look at the history closely.

At nearly 20k a service, even with a FSH it may have only had 5 oil changes including the one they have just promised you it has had. Ignore it and do it as soon as you buy it, along with the Air filter which is a complete swine to do.

Other problems
Gearbox Oil should be changed around 100k miles, the sumps are prone to leaking. Be cautious of clunky gear changes.
Get on a good stretch of road and engage the cruise control, check for surging/fluctuating rpm when on a straight road.

Exhaust Manifold - Prone to cracks. To save weight they changed the cast manifold to one made of tinfoil. Look closely for soot or fumes getting into the cabin.
You won't be able see the soot as it is all hidden so stick a camera down the left hand side of the engine (as you look from the front) and take pictures.

I bought mine at 75k miles and it now has 127k miles.

scaredofdebt

spacey2012 wrote: »

This Myth, that Diesels run for ever .
The oldest most stupid old wife's tale going.

The Old churners of the 80's with 55 BHP might have done.
But these days most Turbo Diesel engines are pretty goosed around 120k.
The internals, will run for ever, it is the bits like DMF fly wheels at £1500 a pop and coded injectors at £1300 a set that kill them off .
If it has had a cheap unbalanced flywheel kit fitted, you can look forward to it going again 20k later.
The days were they run for ever are steeped in mythology.

Agreed to an extent but even so diesels are more economical if you are doing 30k miles or more per annum, in my personal experience.

Funnily enough the most mileage I ever got out of a car was 220k from a 1.2 Vauxhall Nova petrol.

I got 205k miles out of my Mondeo diesel before I decided to scrap it, cost under 20p a mile to run over the time I had it, including everything, depreciation, new DMF, tax, insurance, fuel, MOTs, services and repairs etc.

Herzlos

sillysi wrote: »

Im going through this DPF dilemma at the moment as well .I will probably be buying a new car very soon .The dealer said to go for the diesel but I only do 6k miles ( which I told them )a year so would this be asking for problems ?

If it's mostly long motorway trips and/or doing a lot of towing and you're keeping the car forever then maybe. But realistically; you're not going to be saving enough in fuel economy and tax to cover the increased depreciation/purchase cost of it, let alone the increased maintenance costs.

pulliptears

We bought a 3 year old Focus with a DPF in August last year. 3 months and endless trips back to the dealer with a DPF fault they finally admitted they couldn't fix the problem and refunded in full.
As other half does 35k a year we needed a diesel so in the end opted for the older civic type s that hasn't got one.

Personally we wouldn't touch another with a DPF.

WTFH

pulliptears wrote: »

We bought a 3 year old Focus with a DPF in August last year. 3 months and endless trips back to the dealer with a DPF fault they finally admitted they couldn't fix the problem and refunded in full.
As other half does 35k a year we needed a diesel so in the end opted for the older civic type s that hasn't got one.

Personally we wouldn't touch another with a DPF.

Was it 3 years old with low mileage?

pulliptears

WTFH wrote: »

Was it 3 years old with low mileage?

65k on the clock when we bought it. Credit to the dealers who finally drew a line under the whole saga because of the 3 months we owned the vehicle it was only actually in our possession for 6 weeks.

They replaced the DPF and no end of other parts, by our reckoning they spent easily £1500+ trying to fix it but the error light kept coming back on. I'm guessing it got thrown into an auction somewhere eventually because it never reappeared on the dealers website.

Bambi19

We are currently having a big problem with the DPF on our Mazda 6 (2006). We first noticed that it didn't have much power up hill, and it turns out the DPF is blocked really badly!!! Our options seem to be to remove it all together (not an option as this will make you fail your MOT as of Feb 2014 according to AA), buy a new one and risk it getting clogged again, or try to remove it and pressure wash. Does anyone have any advice on what to do??? We only bought the car last year so any advice would be greatly appreciated!

chib

The argument about the DPF can vary on the car also, I've got a Seat Leon with a 2.0 TDI 170 HP (Commonrail, not Pump Duse - Very big difference) that I use to drive nothing other than town driving (40MPH Max) and it's never been a problem.

It does regen itself every few weeks, noticing the RPM sitting slightly higher at the lights. Had it around 18 months and I'm still waiting on it causing me grief.

It's a brilliant engine too, quieter than some petrol engines - colleague at work has a brand new Astra with a 1.6 petrol that ticks and clicks when idling more than mines does.

Unfortunately about a month after buying the car I moved closer to work and due to only doing short runs my MPG is terrible. I'd like to trade it in for a petrol but the finance outstanding is greater than the trade in value at this point.

Dave_Shane

I am interested in C110 scan tool, where did you get it? It is able to access abs?

Ultrasonic

spacey2012 wrote: »

Yeah and had ten electronic parking brake repairs at £1200 + vat.

I realise this is an old thread but surely most 10 year old VAG diesels don't even have electronic parking brakes? My 05 Octavia doesn't.