A rather alarming sight on the way home was the westbound M4 brought almost to a halt near Slough by a huge cloud of smoke. It turned out to be emanating from the exhaust of an old white van, possibly a Maestro but it was hard to tell. The van had made it to the hard shoulder but the smoke made it impossible to pass any closer than lane 3.
The rest of us marshalled ourselves quite neatly into the right-hand lane and picked our way by but the driver of the van stayed only about a length from his vehicle with his phone to his ear. My concern - assuming this was a case of a diesel engine running out of control on its own engine oil, as we've occasionally discussed here - is how this was going to end. With a whimper, or a bang - and should he have been much further away?
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A search on youtube for "runaway diesel" brings up, among others, this:
www.youtube.com/watch?v=5zx3qKX_Pno
A colleague had it happen to his Rover 45 a few years ago, the engine ran faster and faster consuming its own oil until there was too little oil left to lubricate the moving parts and it slowed down and died.
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Jumper up air intake should stop it dead...
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>> Jumper up air intake should stop it dead...
>>
Not easy to get to in many cars, and possibly extremely hazardous being anywhere near the engine.
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It was the driver's wellbeing I was concerned for. Even if there was no danger of explosive disintegration, the smoke smelled dreadful. The Volvo has an 'air quality monitoring system' that is pretty good at keeping noxious gases out of the cabin, but even that couldn't shut it out altogether; standing five metres away for however long he was there can't have done him any good at all.
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When it happened to me after the garage had overfilled the oil at a service i stalled the engine by putting it in a high gear & trying to move off with brake applied
Have to say it was one of the scariest things I have had in a car as it was going faster & faster with no input from me when it started to happen.
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I thought an engine had to be old and worn out for this to happen? Do engines still get run to the point that their piston rings have failed to the extent that they are pumping oil up into the cylinders?
It was an old tale told of antiquated fishing boats and semi-diesels. How does it happen now with modern engines?
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This was not a modern engine. It was hard to see clearly through the smoke - and I was more concerned with not hitting anything else as I negotiated the hazard - but I'd say the van was at least 15 years old. If it was a Maestro, when did they go out of production?
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>> If it was a Maestro, when did they go out of production?
I drove 100,000 miles in H285HCT, plus a fair few in H585BFT and D592WDO. I'm pretty sure the last new ones I saw around were L or M registration, which would be 1994.
The vans all had the NA Perkins diesel engine in, not the turbo unit. That was only fitted to the cars.
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I believe it can happen if a seal breaks on the turbo unit (especially on the air inwards side).
then oil and air is drawn into the cylinders.
Hence running away on its own.
Id imagine this could happen if there was too much oil in the engine or if a car is NOT serviced on time and one day the turbo gives up.
Another possibility (but not sure how hot Diesel turbo units get) could be heavy use and not allowing the turbo to cool down.
This will wreck the bearings and deform the turbo axle shaft.
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>> I thought an engine had to be old and worn out for this to happen?
>> Do engines still get run to the point that their piston rings have failed to
>> the extent that they are pumping oil up into the cylinders?
>> It was an old tale told of antiquated fishing boats and semi-diesels. How does it
>> happen now with modern engines?
>>
Noooo.... It can happen to nearly new engines!
Especially those fitted with DPF's.
What happens with DPF cars, is if the purging cycle fails to finish, unburnt diesel ends up in the sump.
This raises the oil level (some cars eg Mazda's have low/high/EXCESS marking on the dipstick....)
If the oil isn't changed, and the level continues to rise........ REV - BANG!
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Renault diesels are good for it...
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>> Renault diesels are good for it...
>
They don't do it any more than others.
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A friends 300DTi Discovery started running on sump oil. Failed head gasket was the cause, and he had the presence of mind to quickly stall it. Rebuild didn't cost any more than a head job, although it's a good job he didn't get the bill for the hold up he caused as he was towing and crossing a major junction at the time.
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We had this years ago on a Golf Mk 1 diesel.
But how would one stall an auto diesel with this problem?
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>> We had this years ago on a Golf Mk 1 diesel.
>>
>> But how would one stall an auto diesel with this problem?
>>
In the old days a spud up the exaust pipe seemed to work or was that just on start up of a petrol engine?
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Dunno, but a bag of Smash in the fuel tank oughta do something interesting. Hot diesel flavoured croquette anyone?
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>> Dunno, but a bag of Smash in the fuel tank oughta do something interesting. Hot
>> diesel flavoured croquette anyone?
>
Is that another classic Jock Gordon Blue recipe? From the "munchie box" school of cooking?
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>> But how would one stall an auto diesel with this problem?
I wonder what top speed one of those would reach???
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>> But how would one stall an auto diesel with this problem?
If you put it into drive, the revs would be well contained - the engines are not producing much power when running on their own oil. It takes very little power to rev an engine up when it is not loaded.
Even if the engine were running at maximum fuel, the engine speed would only rise to the so-called stall speed, where the torque convertor would be absorbing the engine power.
This would give some time for someone else to safely take the air pipe off and block the intake with a block of wood or similar.
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>>This would give some time for someone else to safely take the air pipe off and block the intake with a block of wood or similar<<
Assuming one has the necessary 'someone else' + a block of wood handy, if it happened to me in a turbo diesel auto.,
I'd bail out ASAP!
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>> This would give some time for someone else to safely take the air pipe off
>> and block the intake with a block of wood or similar.
>>
"safely"? Let's hope the person in control of the car doesn't let the brake slip! Might be wise to put it in reverse.
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>>"safely"?
Absolutely and completely - for anyone with half a brain.
Anyone daft enough to stand in front of the car might be better removed from the gene pool.
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>> >>"safely"?
>>
>> Absolutely and completely - for anyone with half a brain.
>>
>> Anyone daft enough to stand in front of the car might be better removed from
>> the gene pool.
>>
NC, The 1/2 a brain I have is failing to see just how do you open the bonnet without standing in front of the car?
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You can open the bonnet from the side of most cars - it's not that far to reach
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Yet another reason for me to not buy a diesel.
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If you carry a CO2 fire extinguisher, this should do the trick sprayed near the intake.
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>> If you carry a CO2 fire extinguisher, this should do the trick sprayed near the
>> intake.
>>
I've read that, and it obviously makes sense, but I wonder if it would be big enough to prevent combustion for long enough to halt the engine?
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>> >> If you carry a CO2 fire extinguisher, this should do the trick sprayed near
>> the intake.
>> >>
>> I've read that, and it obviously makes sense, but I wonder if it would be
>> big enough to prevent combustion for long enough to halt the engine?
>>
And you got to get the gas into the intake.
Who knows where their car sucks its air from?
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normally at head light level.
I think its designed that way so that cars can drive through forded streams.
Makes sense really.
The only car I have known not to have an air intake at headlight level was some naff French carp (scenic I think) that had an air inlet very low down near the valance.
I heard a few of these diesel cars giving up the ghost after driving through a few flooded deep puddles.
after all you cant compress water !
Good design - not.
Last edited by: diddy1234 on Wed 28 Mar 12 at 12:31
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Most car extinguishers are dry powder - you emphatically do not want that in an engine*. The race and rally boys (and girls) use AFF which is water based foam, again not the brightest of moves.
Probably only a fire extinguisher salesvan will have CO2 on board although I'd not be surprised if the majority of the stock was water or foam.
*running engines that ingest dry powder have to be taken to bits and every part cleaned.
Last edited by: Slidingpillar on Wed 28 Mar 12 at 13:27
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Any well run workshop should have CO2 extinguishers by each bay for the reason of runaways / welding fires, etc. As I've mentioned before, I keep one with me when I'm working on diesel engines, or welding.
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>> Most car extinguishers are dry powder - you emphatically do not want that in an
>> engine*. The race and rally boys (and girls) use AFF which is water based foam,
>> again not the brightest of moves.
>> *running engines that ingest dry powder have to be taken to bits and every part
>> cleaned.
Whilst I appreciate your mechanical sympathy, I am unclear as to why you show such concern for an ancient engine that has taken to running away. Presumably you wouldn't fancy re-using the engine...
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>> normally at head light level.
>> I think its designed that way so that cars can drive through forded streams.
>>
>> Makes sense really.
>>
>> The only car I have known not to have an air intake at headlight level
>> was some naff French carp (scenic I think) that had an air inlet very low
>> down near the valance.
>> I heard a few of these diesel cars giving up the ghost after driving through
>> a few flooded deep puddles.
>>
>> after all you cant compress water !
>>
>> Good design - not.
>>
See Citroen Xantia...Air intake designed to intake water to keep bonnet line low.
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See Citroen Xantia...Air intake designed to intake water to keep bonnet line low<<
Unless you raise the whole car with the hydraulics and keep your feet dry as well.
(:
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The runaway train must have been a diesel. tinyurl.com/bqqxpjv
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Saw a truck cab this morning I think must have been this. Belching copious amounts of smoke and probably some form of automatic he couldn't stall?
Driver was calmly sitting in cab. I would have been nowhere near it the sound it was making.
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I'm sure I'm being thick here - but why doesn't switching the ignition off stop the engine in cases like these? Clearly it doesn't - or we wouldn't have had 37 posts on the subject - but what's the specific reason for it?
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Stopping a diesel involves interrupting the fuel supply to the injectors. With a runaway, turning the "ignition" off will not halt consumption of the engines own oil from the crankcase. I have known a commercial diesel engine to continue running where the system relied on a pneumatically operated valve to shut off the fuel. When the valve actuation failed (I can't remember the exact details) the engine could not be switched off. In trying to stall the engine in a high gear, the tractor unit (under routine maintenance) simply bounded away in a series of leaps. I saw it replicated afterwards. 10 litres of diesel engine takes some stopping!
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That's why the only reliable method of stopping a runaway diesel engine is to remove air from the equation.
Dumping the clutch in the highest gear wouldn't work on a 150bhp diesel engine. it would just pull at max revs
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>> That's why the only reliable method of stopping a runaway diesel engine is to remove air from the equation.
>>
>> Dumping the clutch in the highest gear wouldn't work on a 150bhp diesel engine.
>> it would just pull at max revs
>>
Would the old spud up the exhaust trick kill it or did that only work with old low powered petrol engines ?
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>> Dumping the clutch in the highest gear wouldn't work on a 150bhp diesel engine. it
>> would just pull at max revs
It will work, a runaway diesel is well past its peak torque curve. Foot on brakes, into gear and letting out the clutch will do it. At worse you will end up with a burned out clutch plate. Unless its an auto of course.
The real point however is, do you still want the car with an engine that's been revving its nuts off well past the limiter and you have managed to stop eventually. I would suggest not, so letting it blow is probably the best course of action.
Last edited by: Zero on Sat 11 May 13 at 19:26
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So, to resurrect an old thread...
Last week this happened to me in our Citroen C8 (57 reg). When pulling away from traffic lights the turbo failed and pulling to the side of the road and seeing increasing smoke from the back of the car I turned the ignition off.
When the engine failed to stop I realised immediately what had happened (from reading this thread initially) and put the car into gear to stall it. All over within a matter of a few seconds, but really quite frightening. My wife didn't know what was happening and in seeing the car being quickly enveloped in the initiated 'emergency get the kids out the car quick' mode.
The car was recovered to a local garage who said I had done the right thing in stalling it when I did (the revs only got to about 2500rpm- goodness only knows how frightening it must be when the engine runs away for longer and on the limiter). New turbo fitted and thankfully all seems to be fine.... for now.
Grateful I had read about it and seen the youtube videos to know what to do.
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Hope the cost wasn't eye watering to have a new turbo fitted.
Btw, did you get an oil change at the same time ?
sometimes the oil pipe to the turbo gets blocked and your new turbo could go the same way as the old one due to lack of lubrication
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It was less eye watering than an engine replacement (which would have effectively meant it would probably be a case of scrapping and buying a new car). A shade over £1200.
The oil was done at the same time. I had contemplated getting the cambelt done now, rather than in a few months time, but the garage (an old school mechanic type) suggested waiting a bit for that part and then getting the service and cambelt done late spring, when an oil change following this work would be helpful. Whether this is the case or not I can't say, but it seemed sensible to me, especially as I was in the situation where the turbo had to be done before they could start the engine and it would be at that point where they would be able to tell if there was further damage that may have cost significantly more than the car was worth.
there was an amount of oil in the exhaust system which I guess may cause problems with emissions come MOT time (?), but short of being a bit smoky for the first 1 or 2 drives it appears now to have cleared.......
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>> goodness only knows how frightening it must be when the engine runs away for longer and on the limiter)
Trouble is, when it runs away on its own oil the limiter is useless - it runs as fast as it can, and then things start to brake, like valves, springs, camshafts etc etc....
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It could all be avoided if diesels still had a decompression lever.
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Most drivers can't even find the bonnet catch, what chance they could find a decompressor - or know what it was for??!!
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OMG things start to BRAKE??? What was I thinking...away to birch myself!
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Runaway diesel: what happened next? - Dave_
