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Author Topic: Detroit Diesel Emergency Shutdown Dampers  (Read 4980 times)
NCbob
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« on: June 15, 2006, 04:05:47 PM »

We've seen, again, from one of the contributors to this board...and I don't mean to single anyone out...a problem which involved an item of equipment which Detroit Diesel had suggested to be defeated or removed some years ago.  Perhaps it was the 'pipe dream' of some young Engineer at DD to solve the possibility and/or rumor that Detroit's run away.

It was found, and the Service Bulletins will bear this out, that using the Emergency Shutdown Damper in the top of the air intake might
shut down a runaway engine but the chances of using it might invert the blower seals and, in effect, give the runaway an alternate source of fuel to burn and it would end up scrap anyway.

I've been near a runaway Detroit many years ago (prior to the damper) and only the application of Co2, in generous amounts, stopped it from disintegrating.

Today, while at the shop where my 8V71 was removed, I asked the Service Manager to remove the Emergency Solenoid and physically remove the damper from the top of the blower intake.  I'd rather live with the chance that my engine would "runaway" than have the problems endured by our friend on this board.

No doubt there will be some who will take me to task for my decision but consider this:  I'm following Detroit Diesel recommendations in regard to this accessory.....and it is MY engine.

Having lived whith these fine engines for well over 40 years and seeing only 1 runaway (the fault of the mechanic who didn't put the cotter pin in the rack before starting the engine) I feel confident that I won't experience the same problem which our friend endured.

NCbob
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Jerry Liebler
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« Reply #1 on: June 15, 2006, 05:01:48 PM »

Bob,
    Since you are determined to remove the 'shut down flap'  it would be a very good idea to switch to the single screw racks.  With the single screw rack one stuck injector won't keep the rest from shutting down and runaway becomes very unlikely.
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Jerry 4107 1120
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NCbob
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« Reply #2 on: June 15, 2006, 05:24:59 PM »

You've got me there Jerry,  am not familiar with 'single screw racks'.  But, with the thousands of hours I've spent with these engines
(over 20 years on DD powered yachts) on a day to day basis, I'm inclined to take the DD engineer's designs with a bit of faith.

Any DD engine, given clean fuel, clean coolant, clean air and and lube oil will outrun (in my opinion) and out last any of the computerized engines produced today.  Call it 'loyalty"...fine with me.

Maintenance is the clear clue to longevity. 

When the Manufacturer says, "Take 'em out"...without reservations...they must know more than  I do.

But since you made the recommendation which you did...I will explore what you've suggested...simply because I'm confident that you did so ...in good faith and my best interests.

NCbob
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DrivingMissLazy
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« Reply #3 on: June 15, 2006, 05:32:53 PM »

I experienced a struck injector on my 6-71 many years ago. I really do not know how I would have shut her down without the flapper. I did not know enough about a DD to maybe find a pair of vice grips and crimp off a fuel line.
Richard

We've seen, again, from one of the contributors to this board...and I don't mean to single anyone out...a problem which involved an item of equipment which Detroit Diesel had suggested to be defeated or removed some years ago.  Perhaps it was the 'pipe dream' of some young Engineer at DD to solve the possibility and/or rumor that Detroit's run away.

It was found, and the Service Bulletins will bear this out, that using the Emergency Shutdown Damper in the top of the air intake might
shut down a runaway engine but the chances of using it might invert the blower seals and, in effect, give the runaway an alternate source of fuel to burn and it would end up scrap anyway.

I've been near a runaway Detroit many years ago (prior to the damper) and only the application of Co2, in generous amounts, stopped it from disintegrating.

Today, while at the shop where my 8V71 was removed, I asked the Service Manager to remove the Emergency Solenoid and physically remove the damper from the top of the blower intake.  I'd rather live with the chance that my engine would "runaway" than have the problems endured by our friend on this board.

No doubt there will be some who will take me to task for my decision but consider this:  I'm following Detroit Diesel recommendations in regard to this accessory.....and it is MY engine.

Having lived with these fine engines for well over 40 years and seeing only 1 runaway (the fault of the mechanic who didn't put the cotter pin in the rack before starting the engine) I feel confident that I won't experience the same problem which our friend endured.

NCbob
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« Reply #4 on: June 15, 2006, 09:25:14 PM »

Richard,

You've just given me a good idea, I'm going to install a shutoff valve on my fuel line next time I have it loose.

I will also keep the emerg shutoff plate since one of our good DD guys around here keeps a 3/8" steel plate in his toolbox for just such use.
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« Reply #5 on: June 16, 2006, 04:32:20 AM »

Activating the emrgency shut down can also be used as a theft deterrent (unless the theif is a DD expert).   Jack
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El-Sonador
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« Reply #6 on: June 16, 2006, 05:01:21 AM »

I like the idea of adding an emergency fuel shut off vale also...

Good Idea...


Steve
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« Reply #7 on: June 16, 2006, 05:57:34 AM »

I like the idea of adding an emergency fuel shut off vale also...

Good Idea...


Steve


Then why not make it a solenoid valve controlled by the run switch?  You would then have control fron the driver's seat as well as the maintenance switch at the engine.

Len
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DrivingMissLazy
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« Reply #8 on: June 16, 2006, 06:08:47 AM »

Maybe just use the existing Emergency Shut Off Switch to control the solenoid?
Richard


Then why not make it a solenoid valve controlled by the run switch?  You would then have control fron the driver's seat as well as the maintenance switch at the engine.

Len
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El-Sonador
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« Reply #9 on: June 16, 2006, 06:11:19 AM »


Then why not make it a solenoid valve controlled by the run switch?  You would then have control fron the driver's seat as well as the maintenance switch at the engine.

Len


That's what I love about this board Len...  Great ideas just keep on rolling in, one after another...

Very talented bunch here...


Steve
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Stan
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« Reply #10 on: June 16, 2006, 09:09:09 AM »

Once an engine runs away, nobody should be close to  it. Large pieces of flying cast iron are more dangerous to your health then the particulate matter that the EPA is regulating. Shutting off the air is the only sure way to stop a runaway diesel.  It can't run on its own oil unless it is getting air. Rep;acing the blower seals is a small price to pay if you have a runaway engine.

I have never been close to an engine when it ran away but I was at the site where a Cat on a 600 KW genset broke a governor rod. At over a 100 feet there were large pieces of metal  embedded in trees.
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« Reply #11 on: June 16, 2006, 09:12:51 AM »

On second thought.....

A solenoid valve installed after the secondary filter would work in the event of a stuck injector or governor failure.

It wouldn't work if the runaway was from the engine running on it's own oil from blown blower seals or clogged airbox drains.
It also wouldn't work if the engine was running on an external fuel source sush as propane or gasoline from a wreck.

Of course, if this happens, you probably have more important things to worry about than a blown engine.

Len
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DrivingMissLazy
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« Reply #12 on: June 16, 2006, 10:19:37 AM »

I strongly suspect that the shutdown damper was primarily installed to stop the engine in case of a stuck injector. I have been told that in the old days this was a fairly common problem. There is really not much danger of an engine flying apart at 2000 rpm. It is in the true runaway situation that it is extremely dangerous.
Richard
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« Reply #13 on: June 16, 2006, 02:09:28 PM »

I wasn't very clear.

The reason for the fuel shutoff valve is not for an emergency stop but if the fuel rack is stuck open or any other reason it won't stop at normal rpm.

Nothing will stop a  runaway if the engine is running on its own oil from blown blower seals or clogged airbox drains.

 I'm not going back there if it is a runaway!!

I think that having a solenoid valve could possibly cause air to enter the fuel line downstream of the valve if it shuts off every time the run switch is turned off. It is also one more electrical thingie to fail.

Simplicity is best.
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« Reply #14 on: June 16, 2006, 06:00:13 PM »

Use the solenoid to operate a ball valve. Put a microswitch on the lever to light up a small lamp if it is tripped or in the off
position.
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