Garage blown my engine - where do I stand?
Discussion
dme123 said:
All they would have had to do is stuff something into the air intake, if it was running away on engine oil then "removing the fuel pipe" obviously wouldn't have achieved anything that switching the ignition off wouldn't have done. I thought most modern diesels had a butterfly valve in the inlet that closed when you switch the ignition off to stop a runaway engine?
Offshore and marine diesels have overspeed flaps in the inlet, but I was not aware that any automotive diesels had them. many years ago I used to formally witness tests of the activation of the overspeed speed flaps on 280 litre, V16 Ruston diesels used on the cross channel catamarans. By god it made a racket when all that metal continued pumping away sucking on a closed inlet! As I recall it was a systems test that they weren't keen on doing as it was not too kind on the engine.As someone commented above, it would be a brave man who approaches an overspeeding engine that has got in its stride. If intervention has not been planned and prepared before starting the car then it's probably too late to get in there and save the situation. And removing the fuel line would do nothing to stop the engine, unless bizarrely it's running away because all the injectors are locked open.
Good luck OP, let's hope the garage recognise their responsibility to replace the engine with an equivalent one from a scrappy.
shoehorn said:
No-one has mentioned the reason that these turbos fail in the first place and it will continue to cause failure until it is replaced.
The crankcase breather/oil seperator in the cam cover,
These are supposed to be changed regularly(70K IIRC)no one ever seems to,they block causing crank gases to push oil back up the return from the turbo,blocking the fresh oil coming in which obviously ruins the turbo. And at the same time,as there is no crankcase gases pressure relief the oil gets pushed past the rings and turbo seals etc.and causes run on.
If you don`t change the breather/seperator you will be fitting a new turbo again soon anyway.
How does this work? Turbos receive oil at pump pressure, typically 30-70psi. If the crankcase is pressurised over 1 psi the engine has bigger problems than a fThe crankcase breather/oil seperator in the cam cover,
These are supposed to be changed regularly(70K IIRC)no one ever seems to,they block causing crank gases to push oil back up the return from the turbo,blocking the fresh oil coming in which obviously ruins the turbo. And at the same time,as there is no crankcase gases pressure relief the oil gets pushed past the rings and turbo seals etc.and causes run on.
If you don`t change the breather/seperator you will be fitting a new turbo again soon anyway.
ked turbo.hidetheelephants said:
How does this work? Turbos receive oil at pump pressure, typically 30-70psi. If the crankcase is pressurised over 1 psi the engine has bigger problems than a fked turbo.
It is certainly a well known fact amongst the few machanics I know and certainly among all the turbo suppliers I have ever used.ked turbo.I do believe that the breathers operation is directly connected with how the electronic turbo actuator controls the turbo,in that it`s factored into the turbo controllers actual software.
A quick Google would confirm the widespread knowledge amongst previously unfortunate owners of the importance of this breather,I suspect.
The filter in the separator becomes hard like a stone and blocked solid,these are now replaced as some one else mentioned earlier with the vortex type.
The oil feed to the turbo is at pressure but is little in quantity and the sump oil/crankcase pressure overcomes it and send that back through the turbo with only one place to go,through the seals.
I have never looked into the actual details of it but guess that with oil feed being common with the rest of the engine the resistance it meets at the turbo oil chamber just causes most of the flow to simply divert somewhere else,a path of least resistance.
I have heard of a test devised using a bastardised pair of return pipes made by an ex BMW tech showing oil travelling back up the turbo return pipe during running and immediately the engine has be switched off.
There has also been cases of it causing inlet manifolds to pop,apparently it makes quite a bang!
This describes the same sort of issue, only on a big V8 diesel:
Source: http://www.powerstroke.org/forum/humor/228435-what...
So what's a diesel run away?
A diesel runaway is when the engine rpm goes up uncontrolled and there is no way the engine can stop itself. Diesel engines don't actually require any controls on then to run. All they need is fuel and air. Gas engines need a spark at just the right time, and a fuel pulse of just the right duration to run. Also, diesels can run on a wide range of fuel. Remember when all of us diesel guys were complaining about leaking injectors on 03's that were filling the crankcase with fuel? Well, 30+ quarts of a fuel/oil mix in the crankcase will submerge the crank. One of the last steps on the diesel diag sheet is an oil aeration test where you have to run the engine at wot (3500 or so rpm) for 3 minutes and then view the oil condition. That crank whipping up the fuel/oil will make a foam that rises through the engine, and eventually starts getting drafted into the intake stream. If there is enough coming into the intake, the engine rpm will start to rise even higher. Of course, this causes the oil to whip more, which makes it rise faster in the engine - a vicious cycle. You cut the key off, but the engine doesn't care - it's getting it's own fuel from another source. Smoke starts to pour from the tailpipe, and the truck starts to vibrate. At about 6000 rpm the ground starts to shake throughout the shop and the sales department looks outside to see if a thunderstorm is coming. 7500 rpm has the shop evacuating - by this time, the whole shop is flooded with smoke. 9000 rpm brings ominous noises from the shop - a cyclic wave of sound that feels like an invisible hand pressing on your chest. Somewhere about 10,000 rpm and the engine gives up. A sound that is a combination of a nearby lightning strike and every toolbox in the shop turning over at once explodes from the shop. The sound echos and continues for several seconds. You can actually feel a shockwave disperse through the concrete you're standing on. And then, the deafening silence. You try to see through the smoke and locate the truck - but something is wrong. It is sitting at an angle, tilted down in the front. And then you see why - both front tires are blown out. There is a scattering of parts 3 bays in each direction. A puddle of fluid is rapidly spreading from under the shredded front cap. The hood and fenders are destroyed, but ironically, the grille and headlights are still intact. And your first thought is - at least I don't have to work on this one anymore! And that, my friend, is a diesel runaway.
Source: http://www.powerstroke.org/forum/humor/228435-what...
So what's a diesel run away?
A diesel runaway is when the engine rpm goes up uncontrolled and there is no way the engine can stop itself. Diesel engines don't actually require any controls on then to run. All they need is fuel and air. Gas engines need a spark at just the right time, and a fuel pulse of just the right duration to run. Also, diesels can run on a wide range of fuel. Remember when all of us diesel guys were complaining about leaking injectors on 03's that were filling the crankcase with fuel? Well, 30+ quarts of a fuel/oil mix in the crankcase will submerge the crank. One of the last steps on the diesel diag sheet is an oil aeration test where you have to run the engine at wot (3500 or so rpm) for 3 minutes and then view the oil condition. That crank whipping up the fuel/oil will make a foam that rises through the engine, and eventually starts getting drafted into the intake stream. If there is enough coming into the intake, the engine rpm will start to rise even higher. Of course, this causes the oil to whip more, which makes it rise faster in the engine - a vicious cycle. You cut the key off, but the engine doesn't care - it's getting it's own fuel from another source. Smoke starts to pour from the tailpipe, and the truck starts to vibrate. At about 6000 rpm the ground starts to shake throughout the shop and the sales department looks outside to see if a thunderstorm is coming. 7500 rpm has the shop evacuating - by this time, the whole shop is flooded with smoke. 9000 rpm brings ominous noises from the shop - a cyclic wave of sound that feels like an invisible hand pressing on your chest. Somewhere about 10,000 rpm and the engine gives up. A sound that is a combination of a nearby lightning strike and every toolbox in the shop turning over at once explodes from the shop. The sound echos and continues for several seconds. You can actually feel a shockwave disperse through the concrete you're standing on. And then, the deafening silence. You try to see through the smoke and locate the truck - but something is wrong. It is sitting at an angle, tilted down in the front. And then you see why - both front tires are blown out. There is a scattering of parts 3 bays in each direction. A puddle of fluid is rapidly spreading from under the shredded front cap. The hood and fenders are destroyed, but ironically, the grille and headlights are still intact. And your first thought is - at least I don't have to work on this one anymore! And that, my friend, is a diesel runaway.
996TT02 said:
The idea that the car would have consumed all it's oil, all 4 or 5 litres of it, is more than a bit far fetched.
Almost certainly the only damage is that related to over revving. Possibly and probably just a couple of bent valves as the garage is saying, once this happens the compression is gone and the reduction in revs due to running on less cylinders won't maintain the running on - after all oil in the inlet tract is not the ideal means of fuelling.
The valves bend because they extend further than the cam pushes them (momentum due to revs) commonly called bounce and hence they contact the piston. Yes the piston gets marked but plenty of cars get rebuilt with marked pistons and it's no big deal.
With a diesel the heavier duty components such as conrods plus the relatively lowish revs possible even when running on - the fuel is slower to burn than petrol - ensure that other forms of over rev damage are not common.
OP, just let the garage sort it out but make sure you don't pay for the extra work.
I do hope so!! :-)Almost certainly the only damage is that related to over revving. Possibly and probably just a couple of bent valves as the garage is saying, once this happens the compression is gone and the reduction in revs due to running on less cylinders won't maintain the running on - after all oil in the inlet tract is not the ideal means of fuelling.
The valves bend because they extend further than the cam pushes them (momentum due to revs) commonly called bounce and hence they contact the piston. Yes the piston gets marked but plenty of cars get rebuilt with marked pistons and it's no big deal.
With a diesel the heavier duty components such as conrods plus the relatively lowish revs possible even when running on - the fuel is slower to burn than petrol - ensure that other forms of over rev damage are not common.
OP, just let the garage sort it out but make sure you don't pay for the extra work.
skyrover said:
Ayahuasca said:
Something else to worry about on my Defender diesel powered vehicle then.
EFAAyahuasca said:
skyrover said:
Ayahuasca said:
Something else to worry about on my Defender diesel powered vehicle then.
EFAAll diesel powered vehicles can run away under the right circumstances
996TT02 said:
The idea that the car would have consumed all it's oil, all 4 or 5 litres of it, is more than a bit far fetched.
OK, so it won't necessarily 'consume' it all as fuel, but during a runaway the lubricating oil won't be being channeled around the engine in the way it should plus a fair amount will be getting chucked out every available orifice as vapour/smoke as the engine is effectively acting as a 9000+rpm oil pump. Oil pressure will be sky high so it'll start bursting seals too - all just accelarating it towards death.Edited by r11co on Wednesday 19th November 14:07
Phateuk said:
What happens after that? Explosion? With hindsight I could have tried stalling it, but as it was on the motorway I hopped over the barrier and left it to destroy itself.
On the plus side, it got rid of my Zafira
yonex said:
I never knew that diesels could do this. Surprising that there is no safety valve that cuts off the air intake when it is running away?
You can fit one of these
http://www.propanetechnologies.com/Pages/Dieselshu...
Injects CO2 into the intake and shuts down the engine... activated with the flick of a switch.
Just to add some positive spin to this:
A friend took his 996 Carrera 4 to a 'one man band' local garage for an oil service.
Work was completed but on the drive home the engine started knocking and then promptly shat itself. Rod through block.
The garage had fitted the wrong oil filter, which had crushed itself under the vacuum of the oil pump and therefore the engine wasn't getting any oil pressure.
The garage simply phoned their insurers right away, an assessor came out and had a look, and my mate got paid out in full for it (car was a write off).
So... As long as the garage have insurance then I can't see why this should be a problem?
Let's assume if the engine is knackered then the garage insurance will pay out?
A friend took his 996 Carrera 4 to a 'one man band' local garage for an oil service.
Work was completed but on the drive home the engine started knocking and then promptly shat itself. Rod through block.
The garage had fitted the wrong oil filter, which had crushed itself under the vacuum of the oil pump and therefore the engine wasn't getting any oil pressure.
The garage simply phoned their insurers right away, an assessor came out and had a look, and my mate got paid out in full for it (car was a write off).
So... As long as the garage have insurance then I can't see why this should be a problem?
Let's assume if the engine is knackered then the garage insurance will pay out?
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