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Old 19-01-2020, 01:17   #31
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Re: How does a diesel shut down

I'm currently dealing with the "how to shutdown" issue on a 6kva kubota powered generator. It currently has a fuel cutoff solenoid valve just before the injector pump and its the worst possible way to stop a generator. It takes a long time to run down and in an overheat or low oil pressure protection shutdown I think there's time for damage to occur. Not only that , it's quite hard to restart!
On this Kubota there is no manual shutdown other than possibly bringing the engine to a negative idle position with the speed control lever which is of necessity, usually locked to maintain frequency.
Paguro and maybe F. Panda use the fuel line solenoid as what I thought was a cheap solution to the lack of an actual stop lever but Paguro sell the fuel solenoid for €450.
This is a 2 pole genset so it's at 3000 rpm and having tried a shutdown with the decompression lever..... I would not advise that as a useful technique.
Captlloyd.....the Detroit mechanic probably had that clipboard to keep track of his hours, every automotive class Detroit from 2-53 up to 16V-92 I've seen has an emergency air intake flap to deal swiftly and decisively with the classic GM runaway.....now just a memory from the past with the introduction of the individually spring loaded rack controllers.
The Deepwater Horizon runaway problem is complex because DP operations have requirements regarding automatic shutdown and redundancy ..... keeping station is critical to avoid losing the wellhead but surely the SMS and class survey would have foreseen the possibility of the Generators breathing an unrestricted hydrocarbon supply after a blowout and the need for an intake air shutoff.
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Old 19-01-2020, 04:50   #32
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Re: How does a diesel shut down

All mechanical drive land drilling and well service rigs have intake shut offs because the engines are close to the wellhead however all modern offshore drilling rigs are diesel electric and consequently the engines are distant enough from the wellhead and consequently they are not required.
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Old 19-01-2020, 08:44   #33
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Re: How does a diesel shut down

Quote:
Originally Posted by skipperpete View Post
I'm currently dealing with the "how to shutdown" issue on a 6kva kubota powered generator. It currently has a fuel cutoff solenoid valve just before the injector pump and its the worst possible way to stop a generator. It takes a long time to run down and in an overheat or low oil pressure protection shutdown I think there's time for damage to occur. Not only that , it's quite hard to restart!
On this Kubota there is no manual shutdown other than possibly bringing the engine to a negative idle position with the speed control lever which is of necessity, usually locked to maintain frequency.
Paguro and maybe F. Panda use the fuel line solenoid as what I thought was a cheap solution to the lack of an actual stop lever but Paguro sell the fuel solenoid for €450.
This is a 2 pole genset so it's at 3000 rpm and having tried a shutdown with the decompression lever..... I would not advise that as a useful technique.
Captlloyd.....the Detroit mechanic probably had that clipboard to keep track of his hours, every automotive class Detroit from 2-53 up to 16V-92 I've seen has an emergency air intake flap to deal swiftly and decisively with the classic GM runaway.....now just a memory from the past with the introduction of the individually spring loaded rack controllers.
The Deepwater Horizon runaway problem is complex because DP operations have requirements regarding automatic shutdown and redundancy ..... keeping station is critical to avoid losing the wellhead but surely the SMS and class survey would have foreseen the possibility of the Generators breathing an unrestricted hydrocarbon supply after a blowout and the need for an intake air shutoff.
Yes, I am sure they have that emergency shut down flap in class but I am talking real world. In the shop when you are test running an engine just rebuilt or working on a rig with an inoperable flap. He personally told me why he kept it there, he was an excellent mechanic. By the way, there has to be about a million old Detroit’s out there still running.
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Old 19-01-2020, 17:42   #34
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Re: How does a diesel shut down

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Originally Posted by RaymondR View Post
All mechanical drive land drilling and well service rigs have intake shut offs because the engines are close to the wellhead however all modern offshore drilling rigs are diesel electric and consequently the engines are distant enough from the wellhead and consequently they are not required.
If the ignition source had not been runaway engines something else would have provided it as none of the electrical equipment in the engine rooms is explosion proof anyway. There are hundreds of contactors and breakers in those spaces housed in unsealed or non explosion proof enclosures.

I would be very cautious regarding blasting a hot engine with a CO2 extinguisher, the CO2 is contained as a liquid and consequently comes out the nozzle freezing cold (CO2 extinguishers are good for cooling beer if someone else is paying for the recharge)
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Old 21-01-2020, 16:56   #35
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Re: How does a diesel shut down

When you push the stop button on your panel you send an electric current to an electromagnet switch. This is located on the fuel throttle assembly. An small arm on this switch closes off the fuel to the throttle system immediately killing the engine. If this switch should fail you could easy install a simple push/pull cable from any Napa for less then 20 dollars.
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Old 24-01-2020, 11:15   #36
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Re: How does a diesel shut down

My experience of runaways have been crankcase fill with fuel. Some engines seem to be more prone. 2 cases were British Fords with injectors under the valve cover . other cases were VW conversions (pathfinder) Haven't had a gmc runaway but there must a reason they include the air cut flap. Maybe a good thing to learn how to stop an engine you've just learned how to start.
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Old 24-01-2020, 11:28   #37
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Re: How does a diesel shut down

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Originally Posted by topmast View Post
My experience of runaways have been crankcase fill with fuel. Some engines seem to be more prone. 2 cases were British Fords with injectors under the valve cover . other cases were VW conversions (pathfinder) Haven't had a gmc runaway but there must a reason they include the air cut flap. Maybe a good thing to learn how to stop an engine you've just learned how to start.
A number of runaway Jimmies on YouTube.
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Old 24-01-2020, 14:50   #38
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Re: How does a diesel shut down

Since diesel auto ignite due to pressure in the cylinder you have to cut the fuel. Normally you should have a handle to pull to choke it.
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Old 24-01-2020, 18:08   #39
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Re: How does a diesel shut down

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Originally Posted by Godshalk View Post
On my Yanmar, the shutoff is actuated by a solenoid. Once, the wire to the solenoid came loose and I could not figure out how to stop the engine - very embarrassing radio call for assistance. I now know that the shutoff can be actuated by hand if you know where it is. (PS I am not a diesels mechanic, in case it's not obvious.)
You can also stop a diesel by covering the air intake with your hand, a flat piece of more or less rigid plastic or similar that would make a seal. I once used a kayak paddle so I didn't have to climb down into the engine space. The wiring to my solenoid failed three times. That was annoying.
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Old 24-01-2020, 19:05   #40
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Re: How does a diesel shut down

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Originally Posted by Diantre View Post
Since diesel auto ignite due to pressure in the cylinder you have to cut the fuel. Normally you should have a handle to pull to choke it.
Welcome aboard CF, Diantre.

Further to your post, the other options (as described upthread) are cut off the air supply or if fitted with de-compression lever(s), remove the compression.
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Old 26-01-2020, 22:07   #41
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Re: How does a diesel shut down

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Originally Posted by skipperpete View Post
I'm currently dealing with the "how to shutdown" issue on a 6kva kubota powered generator. It currently has a fuel cutoff solenoid valve just before the injector pump and its the worst possible way to stop a generator. It takes a long time to run down and in an overheat or low oil pressure protection shutdown I think there's time for damage to occur. Not only that , it's quite hard to restart!
On this Kubota there is no manual shutdown other than possibly bringing the engine to a negative idle position with the speed control lever which is of necessity, usually locked to maintain frequency.
Paguro and maybe F. Panda use the fuel line solenoid as what I thought was a cheap solution to the lack of an actual stop lever but Paguro sell the fuel solenoid for €450.
This is a 2 pole genset so it's at 3000 rpm and having tried a shutdown with the decompression lever..... I would not advise that as a useful.
As a specialist in Generators and stopping of Engines, I wouldn’t be worried about the few seconds the engine takes to stop.
Even in an overheat the Engine temp we see is far less than the capabilities of metal.
and in a Low Oil pressure a few seconds will make will difference, the delay is acceptable. An Engine will run for a while with a loss of oil - but please don’t ever try it.
and I have seen plenty of air shut off systems generally they will starve and slow the engine but not always stop it.

One thing not mentioned in this thread is the injection pressure 3000 PSI in the injector pipes of an old diesel and 1800000 PSI in a modern Common rail engine - So can be dangerous, especially the common rail engines and their fuel systems are operating theatre clean. So watch where you’re putting your fingers. If you don’t know what you’re doing. I have even heard of trained mechanics not always understanding the amount of pressure.
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Old 27-01-2020, 13:03   #42
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Re: How does a diesel shut down

There's a lot of good and interesting info in this thread. Here's a related subject that had me baffled.

My Westerbeke shuts down with a solenoid in the injection pump like many others.

I found out that a mere instrument light out of place can shut everything down instantly.

I had a bulb burn out and didn't have a spare on board so I kept the bad one out to identify it.

The vibration of the running engine cause the brass plate terminal in the engine's instrument cluster to vibrate loose and short the connection. This caused an current overload which tripped the 30A breaker on the engine.

I noticed the terminal was loose and then saw it had some tiny burn marks. I replaced the bulb and the problem was solved. I never would've guess a tiny light bulb could shut my engine down like that! I thought I'd share this since the diagnosis wasn't the most intuitive path. Thankfully this all occurred while I was tied to the dock.
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Old 27-01-2020, 14:14   #43
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Re: How does a diesel shut down

OldCal46Skipper, you didn't mention, but I'm sure you know, that Detroit Diesels like my 1950s 4-53 come with a spring-loaded plate that when released covers the air intake. So, there are two pull knobs on my panel, "Engine Stop" and "Engine Emergency Stop." I've heard, but never seen (maybe you know) that if you've got a real screamer of a run away and pull the "Engine Emergency Stop" she will suck her gaskets and keep running.
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Old 27-01-2020, 14:39   #44
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Re: How does a diesel shut down

No matter how big or fast a runaway engine is, it can only draw one atmosphere of vacuum. An old hotrodders or shade tree mechanics way of getting water out of a carburetor is to rev up the engine and hand choke it.
I still have both hands.
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Old 27-01-2020, 14:46   #45
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Re: How does a diesel shut down

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Originally Posted by Bill Seal View Post
No matter how big or fast a runaway engine is, it can only draw one atmosphere of vacuum. An old hotrodders or shade tree mechanics way of getting water out of a carburetor is to rev up the engine and hand choke it.
I still have both hands.
Yes, an absolute perfect vacuum is pretty much a neg 15 PSI, and that is way more than enough to do serious damage to your hand or other body part, a Diesel may approach that, a spark ignition motor won’t.
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