 | Home > Technical > ..Runaway Defender.. |
 
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| Gareth Member Since: 12 Dec 2011 Location: Woodford Posts: 1107  
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Runaway engine is when a Diesel engine starts to use to own oil as fuel. Usually via a blown turbo seal. They can be very spectacular indeed, YouTube is full of movies of engines going runaway. Usually accompanied by thick smoke, horrible sounds as the engine over revs, valves bounce, seals blow, and eventually it either explodes in a shower of molten metal or simply seizes up!
Not a lot you can do once it's happened. I personally would stay away as explosion could happen. If an engine has started to runaway it's probably  anyway. 2021 Defender 110 X-Dynamic HSE D300 MHEV
1966 S2a 109 aka Betsy |
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18th Jul 2017 7:47am |
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| dorsetsmith Member Since: 30 Oct 2011 Location: South West Posts: 4554 |
or combustible gas but with same outcome
http://www.chalwyn.com/products/air-intake...atic-valve |
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18th Jul 2017 8:00am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17445  
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Just about the only possibilities for stopping a runaway diesel are either to stall it (in a high gear, hard on the brakes, engage clutch) or to block the air intake (if you can get to it safely). If you ever have to attempt the latter, don't use your hand, and don't use something which will just disappear down the pipe and precipitate the destruction of the engine. There will be a great deal of suction going on!
This phenomenon is one of the reasons why LR switched from oil-bath to dry element air filters. On an early diesel overfilling the air filter, or tipping the vehicle over so that the oil in the filter was picked up, could cause this effect. Arguably the only way to get a decent turn of speed out of the 2.0L and 2.286L diesel engines. albeit not for long. |
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18th Jul 2017 8:11am |
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| JWL Member Since: 26 Oct 2011 Location: Hereford Posts: 3443 
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A dry powder fire extinguisher is supposed to be an effective way of stopping it. Touch wood I've never been in the situation
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18th Jul 2017 9:48pm |
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| greenlandrover Member Since: 09 Jul 2017 Location: Stourbridge Posts: 145 
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I had it happen to me on the M5 in a 110 test vehicle from Land Rover.
First I realised something was wrong was sudden loss of power. Looked in my rear view mirror and couldn't see a thing for the smoke. Managed to get over to the hard shoulder where eventually it burned up all its oil and stopped. Highways agency guy turned u just as it happened. Said he'd seen it happen before. AA finally picked me up and took me back to work where it was deposited on the card park. Land Rover turned up the next day and took it away. It came back a day later and seemed to run fine. Think they'd just replaced the turbo! I never saw what engine was in it. Should have looked really. We were developing an ECU for the L316 so it may have been an early Puma mule or could have just been a Td5. We used it for another 10 weeks or so and it was fine from then on! |
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18th Jul 2017 10:01pm |
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| Inigo Member Since: 13 Nov 2011 Location: Kent Posts: 617 
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Happened on my 2.2.
5th gear and dropped the clutch, nothing else stopped it. Had to pay for my own replacement engine, although local dealer made an out of court settlement to cover half of my costs (which were about 10% of the costs had I asked the dealer to replace the engine.) In my case, I believe it was shonky Ford injectors overfuelling, filling up the sump. Seems common, not just on Puma 2.2 engines. A friend had his second Mazda report a dead engine yesterday (too high oil - injectors overfuelling?). I believe that this is a Ford engine as well. I also had an X-type 3.0 that threw a rod at 135,000 miles from new (all mine, all main dealer serviced, less than 3 years from new), also a Ford engine. I'm spotting a theme. |
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19th Jul 2017 12:13am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17445
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The issue of oil dilution with fuel is more commonly down to the DPF regen operation than any kind of injector malfunction, and is the reason that all (or nearly all?) vehicles with DPFs have an Oil Service light.
As I understand it, the regen cycle can be initiated in two ways. The 'best' method, and unfortunately the more expensive method, is to have a separate injector that injects fuel directly into the DPF when regen is needed. The fuel ignites, the soot particles are incinerated and the combustion byproducts shoot out of the exhaust, and everything is good. No enigne damage occurs (I am not sure about environmental damage, but presumably someone has decided that incinerated soot is OK whilst unincinerated soot is bad). The cheap and hence almost universal method, however, works differently. The principle of dosing the DPF with fuel to burn the soot is the same, but the fuel gets there in a very different way. In this method, the ECM is programmed to inject a second dose of fuel into each cylinder during the exhaust stroke of the engine. Since there is no compression on this stroke, the fuel does not ignite and is carried by the exhaust gas from the cylinder to the DPF (or usually combined DPF/Cat) where is is subsequently ignited. Clearly this onlt takes place for a short period every now and then when the DPF regen is needed, but the potential consequences are pretty readily apparent - unburnt fuel is intentionally injected into a cylinder where it will not ignite, and it is inevitable that not all this fuel will be swept up by the exhaust gas and cleared from the cylinder. The residual fuel is then present in the cylinder for another full stroke before (hopefully) being burned off in the next ingition event, and during this time some will migrate past the rings into the sump. In time, especially on vehicles which do predominantly short journeys and regen more frequently, and vehicles with high mileages with more bore wear, this will lead to the sump filling with fuel. As an aside, injector spray patterns are very highly developed and optimised to cause the flame front to travel through the cylinder in a particular way, both to maximise the amount of fuel combusted (and reduce emissions) and prevent diesel knock, there's a whole science to this. Injectors however can only spray one pattern, and I have little doubt that the pattern to optimise combustion is not the pattern you'd use to optimise the atomisation of fuel in the flow of exhaust gas out of the cylinder for a DPF regen. This is one of the reasons - indeed possibly the most significant reason - why I would still buy a 2.4 rather than a 2.2 any day of the week! |
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19th Jul 2017 8:08am |
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| Inigo Member Since: 13 Nov 2011 Location: Kent Posts: 617
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In my case, I had the injectors tested (only after the runaway - so damage may have been caused by runaway rather than the other way around) and found the rearmost cylinder injector to be massively overfuelling. Local engine recon centre that I spoke to said that this is common in the many Ford 2.2 engines they get and correctly predicted in advance which cylinder would have the faulty one.
We did some work in 2008 on the 2.4 Puma engine head. They asked us to design a replica of the cylinder head and a pressure vessel with viewing windows so that they could investigate the spray pattern and flame front. We only got as far as doing drawings though before funding was pulled so not sure if that test rig ever got built. Was a nice idea though. |
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19th Jul 2017 9:43am |
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| Daisy90 Member Since: 01 Feb 2015 Location: Hampshire Posts: 845 
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I worked for a major German company that make rather good artic tractor units,
Anyhow, had one recovered one day, it had start d running on its own oil , and revved to a point that the flywheel let go and came out in lots of directions 
Thankfully the driver had got out a whilst before it happened, The truck was under warranty, but was written off due to the amount of debris damage, let alone the engine / driveline, |
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19th Jul 2017 7:14pm |
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| Welkman Member Since: 02 Nov 2014 Location: Essex colchester Posts: 329
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jesus - that is very scary. Must have been reving very hard indeed maybe >10000rpm?
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21st Jul 2017 11:42am |
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| discomog Member Since: 09 May 2015 Location: Notts/Lincs Border Posts: 2530 
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The most effective way of shutting down a runaway diesel engine is by the use of an automatic air intake shut off valve. Chalwyn valves have been used in the petrochem and oil and gas industries for decades. I'm sure if you contact Chalwyn they can recommend a suitable valve - whether there is room to fit it under the bonnet is another matter. Defender 90XS SW
Mini Countryman Cooper S Morgan Plus 8 |
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21st Jul 2017 1:58pm |
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| Ecco Member Since: 31 Oct 2015 Location: Kuala Lumpur Posts: 280  
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@ discomog
How much such unit cost?? I couldnt fine anything online regarding price ?? |
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22nd Jul 2017 11:59am |
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| discomog Member Since: 09 May 2015 Location: Notts/Lincs Border Posts: 2530
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Quite expensive.
http://www.chalwyn.com/ Defender 90XS SW Mini Countryman Cooper S Morgan Plus 8 |
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22nd Jul 2017 8:21pm |
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| zsd-puma Member Since: 09 Aug 2016 Location: Kent Posts: 2720 
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Probably not even that, most lorries redline at about 4000rpm.
It could be, although it's most likely a Mazda engine, some Ford's use Mazda engines, as they were in partnership with Ford until 2015. Apart from the Puma and TDv8 most current 'Ford' diesels are actually Peugeot designs. (Then Peugeot, Fiat and Citroen also use the Ford designed Puma in some of their large vans just to confuse matters) The Injectors them selves are used by a number of manufacturers, the Denso injectors in the 2.4 Puma are also used by Toyota for example. |
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22nd Jul 2017 8:56pm |
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