| Author |
Message |
Cliff (Floridacracker)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 6:33 pm: | |
While troubleshooting another electrical issue I found that my Emergency Stop Solenoid had been disconnected(end of wire taped off).
I found the circuit up to the solenoid was 100% operational.
This coach was last used commercially by Grayline and I was wondering if this was something they or other operators did routinely?
I am about to read on testing this out in my manual, but any words of wisdom acquired in the 30 years since my manual was written are always appreciated.
Cliff
1975 4905A-1160 |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 7:48 pm: | |
No emergency shutdown assembly on my 6v92. Three mechanics
(two at one bus garage, one at another) said that they disconnect
the leads because it saves on road calls after drivers kill the engine
inadvertently reaching for what they think is the reverse solenoid
switch. One mechanic told me that the flapper wasn't used on
all buses... I'd prefer to have one..just in case.. But they all
said that they've never had a bus engine run off like that...
Ahhh... bus story time:
There was a school bus driver that took a fishbowl
to Hunter Mountain (NY) on a ski run. One the way back,
following an Eagle down Hunter Mountain, he said he lost
his brakes, so he hit the "emergency stop" switch. He ended
up running into the Eagle in front of him, and thankfully that
driver knew enough to keep them both going slow enough
to get them to the bottom of the 6+ mile twisting mountain
road safely. Oh.... On snow covered roads...
(Intercounty Motorcoach... around late 1960s)
I'd test the flapper with the engine not running. |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 10:43 pm: | |
John: Why do you need an air shutdown on a 92 series engine? Why not just turn off the switch? That puts the governor in the no-fuel position. |
sylverstone (Sylverstone_pd4501864)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 11:11 pm: | |
stan:
the 2 stroke diesels, (8v-71, 8v-92, etc) when they mechanically fail with a hole in a piston or the like, are perfectly capable of running off their own lubricating oil, and literally running away with the vehicle, or winding up till they blow up, or start shedding parts (fan blades anyone?) and so on.
the air shutoff is, as far as i know, the "omigoditsgonnablowup" button.
hitting the button can mean the difference between needing a piston, sleeve, and a bit of work, or totally destroying the engine and possibly the coach, etc.
not something i would bypass, especially when it's very easy to make a switch impossible to bump.
-dd |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 11:17 pm: | |
I worry about things like a leak at the seal for the turbo, and
having the engine run off the engine oil.
I had a Mercedes 190d develop a leak in a seal for the vacuum
pump and had engine oil pumped directly into the air intake.
With a small engine and a standard transmission, it was easy
to slip into fourth and apply brakes to stop both engine and vehicle.
But a Bus? No way will you stop a 2 stroke engine that's gone
full tilt. And with an automatic, you can't force it into a higher gear.
A runaway engine will take out everything, one way or the other.
I would feel 100% better installing a shutdown flapper. I'd
rather fix a few blown seals after using it, rather than look
for engine parts in the meadow. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 11:21 pm: | |
(Thanks for the post, sylverstone! You must have been typing 2 strokes faster!) |
RJ Long (Rjlong)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 11:43 pm: | |
John -
You have a turbo 92 series in your bus, don't you?
Good luck finding a flapper shut-down for it - DDA didn't build turbo 92s with them, and AFAIK, the 71 series won't fit.
DDA discontinued the flappers when they went to the individually spring-loaded injectors.
FWIW,
RJ
PD4106-2784
Fresno CA |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 11:49 pm: | |
Really? Good grief man. So how do they shut down a runaway engine?
I believe the guys I talked to, that said they never had one happen, but still..... |
David Evans (Dmd)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 6:47 am: | |
our 4-71 shut its self off rolling thru Richmond at full throttle (62 mph!)When I figured out what had happened and reset the flap she really smoked on restart but was fine after that. I had to wire it open when it happened again an hour later. The cam was worn at the flapper. Filed it flat later to correct it. It definetley shuts her right down. |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 9:06 am: | |
Thanks RJ. I get flamed for not being olite. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 9:38 am: | |
David-
It's good to know that it may not be too damaging to use
the emergency flapper. I think I read it in the manual, that
some damage may occur from it's use.. Maybe only if it's
going full tilt, eh? Helluva lot of suction when that thing's
going full bore.
Rj-
To rephrase my comment to you... It wasn't meant to be
rhetorical!
If the engine is in a runaway state, running on the crankcase
oil, how do you stop the engine without a flapper to shut off
all air intake?
By the way, I have the v92 manual here, and the flapper
assembly(s) are quite clearly shown for the v92 series. I always
respected your comments, and would never claim to know
more than someone else, since there's always something new to learn...
Am I missing something here?
Stan-
"Thanks RJ. I get flamed for not being olite. "
Hmmmm..... "P"d off again!!
HAR!! |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 10:34 am: | |
I used the flapper one time on a 6-71. Had an injector stick open and it held the whole rack open. Was just clearing the crest of a mountain and was really scared what to do till I finally thought of the emergency shutdown. It worked great and did absolutely no damage to the engine. Pulled the valve cover, loosened the sticking injector and came on home on 5 cylinders.
The flapper was eliminated sometime later when a change was made in the injector system and after that there was no way to shut an engine down that was running on its own oil. I know my 6V92 and 8V92 did not have one. I do not know about the V71's.
Richard |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 11:55 am: | |
When you burn a hole in a piston head the engine loses power, it doesn't run away. No compression equals no power.
I expect that somewhere in the world there is a record of DD92 running away becase of leaking turbo seals. I don't personally know of anyone who has seen or heard of it. On the other hand, if you trip an air shut off there is a high risk of takng out the blower seals and the engine will continue to run. On an engine with spring coupled injector rack there is a greater risk of engine damage from accidental tripping of the emergency shut down than from a run away.
The DD 'flapper' valve does not shut off the air completely. If you want that kind of protection, you should buy a 'rig saver valve' which is an air operated slide valve that is used on oil drilling rig engines. That will give you 100% air shut off but almost guarantee the loss of blower seals. |
RJ Long (Rjlong)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 12:06 pm: | |
I stand corrected.
I just got a note on another bbs from a fellow who works at DDA's Reliablt factory. He says the flappers "are out there" on the turbo 71s and 92s, but mostly on industrial and marine applications. Very few on vehicles.
He also says they are still rebuilding a lot of two-strokes, both RH and LH, and LH in both 15 (RTS) and 43 (GMC) degree tilt models.
FWIW,
RJ
PD4106-2784
Fresno CA |
sylverstone (Sylverstone_pd4501864)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 1:19 pm: | |
all i know is what i've been told, and there's at least a dozen old time marine guys around here that have had 8v's run on them. two of them did *not* have flappers on the engines... one of them threw a rod through the bottom of the boat, and the other was shut down by the simple expedient of shoving a life jacket, another life jacket, a hard hat, and 3 wet bath towels down the air intake until it ran out of air.
i have no idea why my scenicruiser came with one, but it makes better sense than anything else i can think of. (my engine is a non turbo)
and i happen to know that it'll stop my bus if it's in gear when i hit it. good thing too.
-dd |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 1:57 pm: | |
Good to know there's another opinion, RJ. The guys at the
bus garage down here were saying just the opposite.
According to them, the marine and industrial engines didn't
have the shutdown, just the engines on the vehicle applications
did.... (prior to OSHA standards?) Supposedly for passenger
safety reasons - engine blowing apart killing people; driver
losing control, etc., it was required..(?) I can't easily locate
any documentation that indicates any "requirement", but then,
I didn't look all that hard (just no time right now). He asked me
if it was turbo. I said yeah, and he said it oughta' have one.
Turbo seals let go, and you have oil straight into the intake.
Yeeegads. Imagine passengers sitting in the back rows, on
top of that runaway engine... Or anyplace near it...
I think common sense would dictate some means of shutting
down an engine that's runaway, burning it's own lubricant and
far exceeding any governing action..... but...
So there we go.. What do we suppose is the correct answer?
I'd much prefer to have a flapper to shut off the air supply,
than to just stand there praying the engine won't blow parts
over a three acre area when it explodes at over 8k rpm. |
Henry R. Bergman, Jr. (Henryofcj)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 7:04 pm: | |
Oh..no!!!!...another old fireman's story which happens to be 100% true. Years ago, the mighty I.S.O. Class 1 Fire Department of Bakersfield California burned up 3 houses pretty much (nice $expensive$ ones too) because of a series of little things that added up to a big thing like burning up three houses.
Not to point fingers at anyone I know, one of the "little" things that went wrong was that a apparatus operator (the driver) of one engine company accidently hit the emergency shut down lever of his 8V71 Detroit Diesel powered pumper.
His could not reset/restart it. Did not know how. Anyway, a simply roof fire went to 3 alarms and the fire chief had to do a lot of explaining to the city manager, city council and to the three families suddendly left homeless.
The point is that at that time Detroit Diesel had the emergency air flapper thing on their motors. The required education for the drivers was NOT forthcoming. It is now, even tho this happened 25 years ago. Long ago and far away. Thanks. |
Jerry@nc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 7:57 pm: | |
I have a 671 in my tugboat and 353 in a crane and they both have flappers I have had to use the one on the 671 when a hyd. line got a pin hole in it and was going down the intake. |
Stephen Fessenden (Sffess)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 8:22 pm: | |
I remember reading on this or another bulletin board that the newer engines had an emergency shutdown that worked on the rack and was supposed to be better than the flapper. Am I remembering right? |
DMDave
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 10:05 pm: | |
All the old Hattaras' boats had emergency shut offs under the throttle levers, little pull T handles. The boat washers always would trip them. |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 21, 2005 - 11:00 pm: | |
Hello show stoppers.
The DD emergency engine shut down feature's intended purpose has more to do with sticking or broken fuel delivery parts than running on lube oil, though that has been known to occur.
Of particular concern for a busnut:
As long as the fuel rack, governor, injectors and all those springs are maintained, everything will be fine. However, if parts are re-used when they shouldn't, if overhauls have not been done, the reliability of the fuel delivery system becomes suspect.
The emergency shut down ended once the electrically controlled injectors came along. Many of the chances for mechanical misadventure are gone.
A busnut, in buying a bus that someone else didn't want anymore, murky past maintenance practices, potentially murkier present preventive maintenance practices, would want to have their emergency shut down functional.
happy coaching!
buswarrior |
Gus Causbie (Gusc)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 22, 2005 - 1:12 am: | |
At a recent truck show at which I had my 4104 on display an old time DD mechanic told me that they always kept a big 1/2" thick steel plate nearby to put over a DD air intake when they were working on them.
He also offered to run my rack just for old times sake, I'll surely take him up on that offer. |
Tim Brandt (Timb)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 22, 2005 - 12:04 pm: | |
One boat I worked on, a converted WW2 minesweeper with Detroits, had two large C02 extinguishers aimed at the airboxes to smother the motors in case of a runaway. If those failed we were to evac the engine room, shut the watertight doors and pull the lever for a secondary system that flooded the entire compartment with C02. If that failed you just had to hope the hole in the bottom wasn't too big and that the bulkheads held |
mikeEMC
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 22, 2005 - 6:01 pm: | |
Being an old marine guy lol i had at least 5 runaways 671 n and m models 871 old navey rebuilds and 1 chysler brand new turbo. i always put a selonoid valve in the fuel line and use co2 to shut down it will compress with out hurting the engine don't use notrogen. the switch has a flap rocker cover one for the fuel selonoid and one for the co2 s-valve so as not to accadently bumb the switch or panic and hit the wrong switch. flaps can shut down but be prapaired to replace seals. if you burn oil after a shutdown you have bad seals. oh by the way use just enought co2 to control the shut down don't try to use to to turn off the engin, slow it down and the fuel will run out. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 22, 2005 - 8:36 pm: | |
Re:
"don't try to use to to turn off the engin, slow it down and
the fuel will run out. "
And if it's running on crankase oil? |
Donald Lee Schwanke (Dontx)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 23, 2005 - 8:30 am: | |
Curious Mike, why not use nitrogen? |
mikeEMC
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 23, 2005 - 10:55 pm: | |
Donald i was told by a machanic some 30 years ago that nitrogen doest compress at high sppeds and could rupture the seals , i guess like nitrogen oxide doest burn it just takes up airspace to increase compression in drag race cars. back then i was a commercial fish nut and repowered with 2 671's and they were already 20 years old ,all i could aford at the time so i ran them 150 hours at a clip and shut down and serviced them . hahaha you couldn't belive what i went through on those engins but never blew one up. |
Donald Lee Schwanke (Dontx)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 23, 2005 - 11:18 pm: | |
Hm, I wonder if we are all speaking of the same thing. Nitrogen compresses very nicely, and makes up 78% of the air you are right now breathing. It doesn't burn or ignite, used to inflate tires, struts, etc. Nitros Oxide again I have no idea about |
Dale L. Waller (Happycampersrus)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, December 24, 2005 - 10:06 am: | |
You don't want to use nitrous oxide to try to stop a runaway diesel.
Nitrous is used to get more oxygen into an engine to build more power.
If I can recall nitrous breaks down at 572 F on the compression stroke to release oxygen into the cylinder.
So injecting nitrous into a runaway engine would be feeding it more oxygen. Then KABOOM. |