How to stop a diesel engine

MarkJohnson12345

MarkJohnson12345

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Just to follow up on a previous post, how does one stop a diesel engine when the 'norma' controls are crisps??

I have been told that you can stop it by lifting the valves with the decompressor lever.

I would be worried about doing that, but it would certainly work??

I switched of the main fuel tap, but thast effectively was useless, as there is so much fule in the filters and pipelines.

In the end I took off the filter bowl, and it still ran for three minutes.

Blocking the air supply would work, but getting the air filter off is difficullt when the engine is cold.

But its got to be air or fuel......



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wooden tapered bung in the air is the only way, some engines still can run because of diesel in the sump. stop the air and you stop the engine.
Problem with the engines running from the sump is they blow up as they have no regulation and overspeed.
 
Put a rag over the air inlet - An engine can not run without air. If a small engine you can even use the flat of your hand, just ensure no air is getting past - it will stop straight away.
 
as already commented on your earlier post I'm a firm believer in the cut off the air supply option, but it does depend on the air filter design - if a pancake design then more troublesome to effectively block than the more common inlet pipe into filter box option although a strong polythene bag put over the pancake and held down would probabaly do the job. On engines where there is a length of hose between the filter and the engine then simply pinch the hose flat or fold the hose into a tight kink. The main challenge with all the above is the need to safely reach over various bits of whizzing alternator & fan belt.
 
Definitely block off the air supply. This happened to me several years ago when working on a Lister TS3 fitted with a hydraulic pump. The pump had been fitted with incorrect rotation so promptly pumped oil into the sump and even with the fuel shut off the engine ran away burning the sump/hydraulic oil. The workshop filled with acrid white smoke and the only way I stopped it was wrenching off the air cleaner and putting my hand over the inlet and it stopped. A bit scary at the time as I was alone in the workshop.......
 
Hand over the air intake IS DEFINITELY dangerous. If it's a little engine running slowly you may get away without injury but I once saw a guy who tried it with a big Cummins. Not only did it break the skin, it broke several bones in his hand and it was a real bloody mess. He never did recover the full use of it..... DON'T DO IT. If you must stop it that way find something flat like a piece of wood or if its got a perforated filter on the intake try a plastic bag but not your hand.....
 
You should never cut-off the fuel supply to a diesel engine and should also try never to run out of fuel. The diesel injection pump is lubricated by the fuel passing through it and when you consider that the manufacturing tolerances are down to 1/10 of a micron you can seriously damage the pump.
 
If the solenoid fuel switch is not working or unavailable, I believe the quickest and safest way is to use the decompressor / valve lifter. The main downside is that the engine continues to spin for some time so unburned fuel can accumulate and may wash down the bores. I don't think there should be a risk to the valves since there is no ignition because there is no compression. The only risk to valves is, of course, if using the lifter results in the valve being hit by the piston - but it shouldn't if it's properly designed and fitted. Blocking the air intake can also work but is sometimes not easy to do.

Using the decompression lever was the recommended way to stop some old diesels such as Petters back in the '70's when I worked for them.
Morgan
 
That sounds an idea.

I think that lifting the valves was probably the way to stop the beast. But suspect it would put strain on any weakness's there.

Appreciate the fuel starvation has its downside, but I guess engines do run out of fuel inadvertantly sometimes, so must be able to live with that occaisonaly.
 
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You should never cut-off the fuel supply to a diesel engine

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You are getting confused between running out of fuel and cutting off the fuel supply. Most modern diesels have a fuel cutoff solenoid which is how they are normally stopped. If this fails there is usually a manual cutoff button (often under a rubber cover on the end of the solenoid) Many owners never familiarise themselves with this but it's worth knowing where it is in case of electrical failure. If an old engine does not have such a cutoff and has a valve lifter this is a perfectly acceptable method of stopping the engine. Usually though even these have a manual cutoff at the pump. There should never be a need to stop the engine by shutting off the air intake.
 
Surely if you are faced with the, fortunately very rare, situation of a diesel running away on its own lubricating oil, then the only way to stop it would be to obstruct the air supply?

Presumably decompressing would also work in this situation?
 
Very rare and very dangerous, most engines that run away because "fuel" is supplied via the air inlet or sump oil getting into the combustion chamber somehow tend to break because they over rev and something important breaks - crankshaft, con rod, piston, flywheel comes off etc..

Anyway its very rare. WHAT EVER YOU DO DONT BLOCK THE AIR INTAKE WITH ANY THING THAT IS HARD TO REPLACE, like a hand or a foot, or a leg, IT WILL BE DESTROYED.

I think I would use water in the air intake then buy another engine!

Getting back to normality, to stop a diesel, dont let this be a surprise, before you need the knowledge find out by inspection which bit of the engine moves when the stop contol is used, be it a cable or a solenoid. If the cable snaps or solenoid takes an early bath, move that bit manualy, with a piece of string, wire, pliers what ever.

What is happening when that control is moved is that the injector pump is "set" to pump "no fuel" without fuel the engine stops. You could just turn off the fuel and wait, but restarting would/could be a bit of a pain.
 
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Most injector pumps have a throttle link and usually a stop link, moving one will accelerate the engine the other will stop the engine.

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Exactly. As a Diesel has mo spark ignition - the only way to stop one is use the fuel cut-of in the pump. That's where solenoid is usually connected to as the old fashioned pull cable.
 
A few decades ago there was a notorious stretch of road along which HGVs tended to shunt into the back of other vehicles with the drivers swearing blind that they had had no control. It turned out that they had been driving in a dip in the road, and that there was an LPG storage facility was above it, with a leak. The LPG (butane or propane) had flowed down the hill into the dip and as soon as the HGV engine started to take in the gas, it accelerated! I can't remember the stretch of road, but it is probably googleable.
 
[ QUOTE ]
Exactly. As a Diesel has mo spark ignition - the only way to stop one is use the fuel cut-of in the pump. That's where solenoid is usually connected to as the old fashioned pull cable.

[/ QUOTE ]

You stuff a rag up the air intake, no air, no bang, engine stops.

From father many many years ago. he used to run a large garage, they had a lorry engine run away, mechanics evacuated, father stuffed his white coat up air intake, engine engine stops, removes white coat, puts back on and walks away.

Brian
 
Anyone remember this from Scrapheap Challange

Quote from website

"The Barley Pickers faced some real problems. How do you make a seven-tonne tractor go from 45mph to infinity and beyond? Answer: you add another gearbox to crank up the revs. Unfortunately, Devonshire's finest couldn't find another gearbox in the yard, so they went for some drastic measures. While tinkering with the engine's 'governor' (see Science) while on tickover, a nut fell off in Andy's hand. The 16-cylinder 'snorter' went bananas. The revs were off the scale and the team legged it as smoke and noise erupted over the yard. The Boat Buoys jumped in to help the farmers and after ripping off the fuel lines and suffocating the engine, the whole rig died with a nasty 'chundering' sound. Oh dear. "

Wonder if I can find a video?

Ash
 
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