TD's and stuck throttles

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p20
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TD's and stuck throttles

Post by p20 »

On sunday, whilst at work( for the ambulance service) we came across a huge cloud of smoke, across both sides of the dual carriage way. At the centre of this was 3yr old td laguna parked on a slip road with its throttle stuck fully open.
It actually belongs to my mate, who's wife was driving it at the time. She had two dashboard lights come on, then the revs soared. She was unable to stop the engine. She parked up and the 3 occupants got out and retreated to a safe distance.
I managed to stall the car and remove the cars card/key thing. The smoke had been from the exhaust, and soon cleared, just leaving the bonnet smoking. The fire brigade arrived and confirmed that it was now safe and 'not going to burst into flames'
This is the second td car(the other was a 2yr old focus) that has had this problem that i know of. The focus did catch fire.

Is this more common than we realise and what's the most likely cause?
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Post by Kowalski »

What is likely to have happened is that the engine starting using its own engine oil as fuel, there must have been plenty of oil available to it to make it run and smoke as you have described. All it takes is leaky turbo bearings or overfilling the engine with oil and the engine will run away. A further possibility (on older engines, not the Laguna or Focus) is that the governer on the injector pump can stick and that can make the engine run away but this time on diesel, this is a bit like having the throttle stick open on a petrol car.

It can happen to diesels and diesels are becoming more common, so it will become more common.
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Post by bxbodger »

I'd imagine that on a newish engine, assuming it hasn't been overfilled with oil, this is also very likely to be down to gremlins in electronic pump and injector systems.

The days of the old mechanical pump and governor are long gone, and its now mostly done by elastic-trickery, which is normally extremely reliable, but when it goes wrong.............. :shock:
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Re: TD's and stuck throttles

Post by Homer »

p20 wrote:She was unable to stop the engine.
........
I managed to stall the car and remove the cars card/key thing.
What had she tried in order to stop the engine? Does the card have some kind of interlock which prevents it being removed with the engine running? Will/did the engine continue to run with the card removed?

On a modern diesel I would imagine killing the ignition would kill the fuel pump and hence the fuel supply to the engine. Which would suggest it was then running on it's own engine oil.

At least she managed to stop the car and get out which is better than the numpty in the BMW who decided it would be better to carry on at 135mph than turn off the ignition and have slightly heavy steering at 70mph.
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Post by James.UK »

So... Faced with a runaway diesel engine, what is the best way to stop it?? :roll: :? :( And what options are there?
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Post by fastandfurryous »

Runaway diesel engine.... 5th gear, clutch up, then stand on the brakes and stall it.

theoretically you can also block the air intake, but personally I wouldn't go anywhere near an engine revving it'self to pieces. The chances of it throwing a rod are a lot higher when it's out of control! :shock:
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Post by Kowalski »

fastandfurryous wrote:Runaway diesel engine.... 5th gear, clutch up, then stand on the brakes and stall it.
Its not an ideal situation to being in, having a runaway engine, but if you want to wreck a gearbox, sticking it in 5th and dumping the clutch with the engine reving is as good a way of breaking something as I can think of.

If the engine has runaway its not being rev limited so it can over rev and damage itself, then it'll stop. It may have already done itself damage, you'd have to decide whether risking damaging your gearbox was the best thing to do considering your engine may have already damaged itself. Its a hard choice really isn't it, but you don't really have another option. The engine will stop when it runs out of fuel (engine oil) or it breaks itself.

On the Scrappy Races when they had their diesel engine run away, it stopped itself after it over-reved and the pistons and valves got together, knackered engine.
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Post by 406 V6 »

I used to do this on 2nd hand a Vespa i had. It sometimes got out of control, even switching the ignition off.
The mechanic i bought it from had this huuuge grin on his face when i went there to check the g/b oil and the engine wouldn't shut down. So, 3rd gear, rear brake pushed really hard and *slowly* releasing the clutch. No one on his right mind would simply get the foot out of the clutch pedal...
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Post by p20 »

On the Laguna it doesn't have an ignition barrel, just a card slot and a stop/start switch, which did nothing. You can't remove the card whilst the engine is running. I just think in the madness of the event she just didn't think clearly enough to stall it.
I did expect the car to really kick when i stalled it, but it stopped very easily, no real pull or kick
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Re: TD's and stuck throttles

Post by reblack68 »

Homer wrote:At least she managed to stop the car and get out which is better than the numpty in the BMW who decided it would be better to carry on at 135mph than turn off the ignition and have slightly heavy steering at 70mph.
That's just what I was thinking when I read that!

I don't think I'd ever be able to trust the car again if it did that to me.
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Post by James.UK »

Hmm putting an automatic in gear with the engine revving its head off would be interesting?? And my diesel ZX is auto!! :roll: :? .. I imagine a huge cloud of burning tyre rubber and 0 to 60 in 3secs?? I would get slanty eyes and ribs mixed up with my spine lol.. But as my auto box has to go through reverse first, it might be even more interesting!! :shock: :roll:
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Post by Homer »

p20 wrote:On the Laguna it doesn't have an ignition barrel, just a card slot and a stop/start switch, which did nothing. You can't remove the card whilst the engine is running.
Assuming the stop switch was doing what it should the engine must have (as has been suggested) been running on engine oil.

On the other hand if the stop switch is not a hard wired cutoff and the engine was running properly the possibilities are quite terrifying.

With an auto the brakes should be able to stop the car provided you stand on them hard from the outset to avoid prolonged gentle braking which will burn out the pads and boil the brake fluid on a non LHM car. What it will do to the torque converter with the engine racing and the car stationary is anyones guess. And I wouldn't want to be sat in the car for long in case something went bang big style.
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Post by fastandfurryous »

Kowalski wrote:
fastandfurryous wrote:Runaway diesel engine.... 5th gear, clutch up, then stand on the brakes and stall it.
Its not an ideal situation to being in, having a runaway engine, but if you want to wreck a gearbox, sticking it in 5th and dumping the clutch with the engine reving is as good a way of breaking something as I can think of.
Dumping the clutch is not what I recommended. If you read the procedure, it states that you have the clutch up BEFORE standing on the brakes. The point is that you will be moving when the engine runs away, most likely on the motorway, so you engage 5th gear (to give best mechanical advantage to the brakes) make sure the clutch is up, and THEN stand hard on the brakes, coming to a stop and stalling the engine.

I've had a diesel run away with me on it's engine oil before, and can confirm that this procedure works fine. I managed to stall the engine before it damaged itself, and drove the car home after it had cooled down.

If you've an auto then you've a problem as you can't stall an auto, and if you stand on the brakes it will just overheat the torque converter. In this instance you're probably best off allowing the engine to expire on it's own.
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Post by PowerLee »

Ahhhhh

Laguna II

I bet it was a 1.9 DCi

Theres a VERY WELL known problem on this engine.

The EGR valve fails & dumps oil into the turbo charger, The turbo then dumps this oil into the inlet of the engine & it revs its tits off & goes BANG!!!

The end result is new engine, new turbo & most important NEW EGR valve!

Try getting hold of a 1.9 DCi engine from a breakers, Theres a waiting list for these, Also you WILL be charged top money for one when you get to the top of the list.

Most car traders WONT touch a Laguna II diesel, They can be picked up well cheap from car auctions because nobody wants them because of this very problem :wink:

Only an IDIOT would go out & buy a Laguna II 1.9 DCi :shock:
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Post by reblack68 »

Is it the kind of thing you could avoid by replacing the EGR valve regularly or can it hapen at any time?


Yes I know the correct way to avoid it is by not buying a Laguna. :roll:
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