sad day for this motor :( Might wanna turn the volume down :)
https://video-atl1-1.xx.fbcdn.net/hvideo-xfp1/v/l/t42.1790-2/11183976_1139709659378843_1243429475_n.mp4?efg=eyJybHIiOjU3MiwicmxhIjoxMDU2fQ%3D%3D&rl=572&vabr=318&oh=797d7eac9905b2e6251360d498e4b90e&oe=55A88BC1 (https://video-atl1-1.xx.fbcdn.net/hvideo-xfp1/v/l/t42.1790-2/11183976_1139709659378843_1243429475_n.mp4?efg=eyJybHIiOjU3MiwicmxhIjoxMDU2fQ%3D%3D&rl=572&vabr=318&oh=797d7eac9905b2e6251360d498e4b90e&oe=55A88BC1)
Yep ... very sad. Also very expensive. And that is why, before the dawn of time, our old beloved DD 2 strokes (the early ones) had that blower intake flapper thingie that could be slammed down with suction and spring pressure shutting off nearly all the air. Better to blow some seals than toast the entire engine. I was told the world record for a run a way Detroit, (probably without the shut down thingie) was about 4500 rpm? Then the valves float? Dunno fur sures. HB
That also leads into a very expensive interesting story which shall be saved for later. :)
That's what happens when you blow a turbo and the engine runs away on the engine oil. Good Luck, TomC
If you turned on the Jakes, would that be enough to stop a runaway, at least in a 2-stroke? If the engine's got no compression, surely the oil can't combust in the cylinders? I don't know if this plan would work with a 4-stroke because Suck Squeeze Bang Blow occurs over twice the number of piston movements. If the Jake plan works, it could be better than blocking the inlet or firing a CO2 extinguisher into the intake or whatever other ways.
Just an idea. (I thought of it in the shower - all my best/worst thinking happens in the shower.)
John
The old coal truck I used to drive (GM 5 over 4 tranny) had a "T" handle that was a compression release. You pull it so that there was no compression on the engine and when the starter was up to speed, you push it in to start the engine. The only way to shut the engine down was to pull the T handle, releasing the engine compression. Why is there not a compression release on these buses? just thinking Danny
If you turned on the Jakes on a runaway engine past 2300 RPM (from turbo oil) you would stop the engine but bend half the valves (the ones the Jake are holding open). If you could stand the noise the best thing is to cut off the air supply, but that would take time and nerves of steel. Runaway Detroits make my heart rate explode-- this is known from a few incidents.
--Geoff
Quote from: Iceni John on July 16, 2015, 11:04:50 PM
If you turned on the Jakes, would that be enough to stop a runaway, at least in a 2-stroke? If the engine's got no compression, surely the oil can't combust in the cylinders? I don't know if this plan would work with a 4-stroke because Suck Squeeze Bang Blow occurs over twice the number of piston movements. If the Jake plan works, it could be better than blocking the inlet or firing a CO2 extinguisher into the intake or whatever other ways.
Just an idea. (I thought of it in the shower - all my best/worst thinking happens in the shower.)
John
I cut a hole in the side of our MCI 9 and stuck stainless mesh over it so I could pull it off and slap a clipboard over the intake rubber grommet.
Quote from: Scott Bennett on July 17, 2015, 09:08:04 AM
I cut a hole in the side of our MCI 9 and stuck stainless mesh over it so I could pull it off and slap a clipboard over the intake rubber grommet.
in this runaway scenario, a clip board could possibly/likely be ingested also...that's why airhorn flappers were steel :)
Why would the valves bend? I do not understand. HB
Quote from: Geoff on July 17, 2015, 08:06:15 AM
If you turned on the Jakes on a runaway engine past 2300 RPM (from turbo oil) you would stop the engine but bend half the valves (the ones the Jake are holding open). If you could stand the noise the best thing is to cut off the air supply, but that would take time and nerves of steel. Runaway Detroits make my heart rate explode-- this is known from a few incidents.
--Geoff
On second thoughts, turning on the Jakes may not work, because they should only work when in gear or lockup and when at No Fuel, and when the Ignition run switch is on. If the Jakes had an extra switch to send power in an emergency to their solenoids regardless of the usual operating parameters, even with the Ignition turned off, that could stop the engine just like the old Cummins compression release, and the risk of bending half the exhaust valves is better than definitely trashing the whole engine! Would the valves bend because they are floating open at those high revs?
John
Aha then! My clipboard shalt be made of steel!
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On the video, don't understand why the guy didn't just stick it in gear and let out the clutch? Course you do some non thinking things in emergencies. Good Luck, TomC
Quote from: Iceni John on July 17, 2015, 03:20:59 PM
On second thoughts, turning on the Jakes may not work, because they should only work when in gear or lockup and when at No Fuel, and when the Ignition run switch is on. If the Jakes had an extra switch to send power in an emergency to their solenoids regardless of the usual operating parameters, even with the Ignition turned off, that could stop the engine just like the old Cummins compression release, and the risk of bending half the exhaust valves is better than definitely trashing the whole engine! Would the valves bend because they are floating open at those high revs?
John
Lets see, if the Detroit is a "runaway", and is running on turbo oil, then you are not going to be pushing on the throttle, so the Jake micro switch would be in the idle position so the Jakes would come on at high speed. And if the Jakes come on at high speed, they are holding two valves open which would make them kiss the pistons. And yes, you can even make the valves hit the pistons by over revving the engine (like coasting down a hill in too low a gear).
--Geoff
Quote from: Scott Bennett on July 19, 2015, 05:56:03 AM
Aha then! My clipboard shalt be made of steel!
Sent from my iPhone using Tapatalk
the aluminium ones with the folding cover work very well too... (https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fecx.images-amazon.com%2Fimages%2FI%2F4185chcFV5L.jpg&hash=4b1000cb2d9ddfcff143be31d718ed35897ec51a)
and will look very
professional doing
either job :)
i prefer this one... http://www.amazon.com/Saunders-10519-Recycled-Aluminum-Snapak/dp/B0007UO4OQ/ref=sr_1_20?s=office-products&ie=UTF8&qid=1437326064&sr=1-20&keywords=Aluminum++Clipboard (http://www.amazon.com/Saunders-10519-Recycled-Aluminum-Snapak/dp/B0007UO4OQ/ref=sr_1_20?s=office-products&ie=UTF8&qid=1437326064&sr=1-20&keywords=Aluminum++Clipboard)
PS cut and pasted for your conveniance and --- --- ----'s irritation... ;D
All diesel engines will runaway I have seen my share of Cummins and Cat engines destroy their self,worst I ever saw was a JT Cummins mounted vertical on a pump we dodged flying parts for 10 minutes when it got a dose of natural gas
^ now that's funny. but not...but funny.... :o ;D :o
Quote from: Scott Bennett on July 19, 2015, 11:17:33 AM
^ now that's funny. but not...but funny.... :o ;D :o
But.... I get to chuckle twice ... ;D
The worst runaway I was witness too started out like this...
I had replaced a head on an old 12E Cat grader on a job.
The boss (Master Mechanic) was doosh...
The oiler was .... apprehensive... to say the least...
The oiler was to add oil and grease the machine...and change the air filter... he did not have one... I saw him "cleaning" the old one...in gasoline....
I asked him what he was doing...he said...he was instructed by the MMd... I said you know what's going to happen ? uhuh he says...
I said were I you...I'd run that filter over with a loader...
so... I buttoned up my portion of the job... and as I was packing my tools.... I heard this awful sound....
I never looked back. :-\ :o >:( ;D
I checked the operation of the flapper valve on my MC8 not long after I bought it. Just a dry run without the engine actually running.
Trip solenoid operated OK but the valve didn't move - because the shaft was seized solid in the housing.
After an hour of freeing it up and then pulling it apart it worked as it should, and now I check it every few months.
Quote from: eagle19952 on July 19, 2015, 03:33:22 PM
But.... I get to chuckle twice ... ;D
The worst runaway I was witness too started out like this...
I had replaced a head on an old 12E Cat grader on a job.
The boss (Master Mechanic) was doosh...
The oiler was .... apprehensive... to say the least...
The oiler was to add oil and grease the machine...and change the air filter... he did not have one... I saw him "cleaning" the old one...in gasoline....
I asked him what he was doing...he said...he was instructed by the MMd... I said you know what's going to happen ? uhuh he says...
I said were I you...I'd run that filter over with a loader...
so... I buttoned up my portion of the job... and as I was packing my tools.... I heard this awful sound....
I never looked back. :-\ :o >:( ;D
Seriously, this event clearly makes me lose faith in humanity. How on earth did we survive this long? * shaking head *
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