500 diesel running away

[longdog]

p { margin-bottom: 0.21cm; } [FONT=DejaVu Sans, sans-serif]Honest John's piece in the Telegraph motoring section of 10 August featured a 2008 500 diesel of which the engine, after 25,000 miles, had blown white smoke, revved uncontrollably even after the ignition was switched off, and then died. HJ claims this is a well-known problem with this engine: the ECU introduces too much fuel in an attempt to regenerate the DPF, the extra fuel sinks into the sump, it raises the oil level, and the engine then starts to run on it. He says it is vital that the oil level be checked weekly and that if it has risen the oil be changed and the DPF be serviced.[/FONT]


[FONT=DejaVu Sans, sans-serif]So I checked the level on my 2011 Ypsilon diesel (similar engine) and it appears possible that it has risen slightly in the 5000 miles since the oil was changed. My car has done 26,000 miles, with very few short journeys and many very long ones, and the DPF light has never come on. The car in HJ's article appears to have done very little annual mileage, so it may have been used mainly for short journeys.[/FONT]


[FONT=DejaVu Sans, sans-serif]I wonder whether an expert can shed light on the problem? How common is it? If there was a problem, has it been sorted now? If fuel is getting into the sump, even if the engine doesn't run away, does the performance of the oil suffer to a serious extent?[/FONT]

 

[varesecrazy]

Hi,
the 1.3 engine is used in LOTS of FIAT and Vauxhall , cars + light vans,
is DOES happen - as there are hundreds of thousands of them on the road..!!

but hardly a common occurence Journo's for you..!!:bang:

your vehicle SHOULD regenerate.., IF it's equipped to..
you can actually force it to with a laptop - ( eg. MultiECUScan)
the forged regen actually introduces EXTRA FUEL( which can become a contaminant)

look in the 2012 Panda section for reassurance ,

Charlie - Oxford

 

[s130]

Oil dilution with diesel on cars with DPFs is a known issue but when it does happen the normal worst case outcome is a seized engine due to the bearings being lubricated with fuel as opposed to diesel runaway issues.

Diesel runaway is not strictly related to cars with DPFs. Any diesel engine can suffer this when the piston rings / bores wear excessively. Then what happens is that oil vapour from the sump basses into the bores, gets compressed and ignites and the cycle continues unabated. Engine just revs its nuts off till eventual death.

Going back to oil dilution on cars with DPFs this will not normally happen if the starts it regeneration process and is allowed to complete the process. During regeneration the extra fuel is partly burnt but the majority exists down the exhaust to set fire to the DPF. All things being equal the process is pretty well balanced and there is no excess fuel.

The main problem is when the regeneration cycle is continually interrupted. This leaves the bores rich with diesel fuel that is not burnt as fuel or pushed down the exhaust to the DPF. The fuel then drains down into the sump overnight/time. We are talking small amounts of fuel but now for the big problem.

Cars that get regularly driven on runs with repeated patterns and distances (e.g. school runs) can start regeneration only to be shut off. This pattern repeats the next day because the last regen was incomplete so it kicks off again. And then the next day ....... etc. The whole typical driving cycle and regeneration cycle get interlocked. Now this is when the real oil dilution is happening as the cycle repeats again and again.

If you have a car with a DPF then you should be able to tell when a DPF regen is happening. Clues are:

o slightly lumpy idle vibration from engine
o possible slight overrun when lifting foot of throttle pedal
o extreme heat from under car when door is open
o very hot smell / intense exhaust temperature

If at all practical you should carry on driving or let the car idle to finish the regen cycle before switching off the engine. To carry on driving is the preferred method as this is least stressful to the car in general as all this incredible heat that builds up is taken away by the passage of air underneath car which obviously cools the exhaust and underside but also draws hot air from the engine bay.

 

[Most Easterly Pandas]

Just to add, it is for this very reason that when the oil is changed the Oil Degradation Index (not only the service indicator, these are 2 different systems) MUST be reset!

Also, the HJ chap is a generic idiot from what I can see with the stuff he posts, and it may not have even been due to DPF issues, could have been failure of turbo seals etc.

Turning a car off mid regen will not cause any issues, and its designed to do this providing the car is serviced correctly, providing the DPF warning light isn't on. Its only if that light is on you should either continue to drive it or leave the engine running until the Regen stops.

 

[longdog]

My thanks to all three of the respondents above for the very useful answers they have provided. I feel this information on DPFs ought to be more widely disseminated. I need hardly say that the Ypsilon owner's handbook is completely silent on the subject.

 

[varesecrazy]

My thanks to all three of the respondents above for the very useful answers they have provided. I feel this information on DPFs ought to be more widely disseminated. I need hardly say that the Ypsilon owner's handbook is completely silent on the subject.

no problem,

personally - I would try and investigate your vehicles apparent lack of regen's,


charlie