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| 1876.1 | don't ignore and hope for the best | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 16:38 | 63 |
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Note 1876.1 Runaway diesel! 1 of 11
UNIFIX::BERENS "Alan Berens" 53 lines 10-JUN-1992 09:33
-< don't ignore and hope for the best >-
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1) Have there been other instances of runaway diesels? (Yanmars, in
particular)
Yes, this is unfortunately not uncommon. All a diesel needs to run is
air and fuel. As long as there is sufficient fuel from somewhere, the
engine will run. If the piston rings or valve guides are sufficiently
worn, enough crankcase oil can reach the cylinders to keep the engine
running. One autumn I sprayed fogging oil into the air intake of my
diesel while cranking the engine with the injector pump fuel shutoff closed.
I was quite surprised when the engine started and continued running
(very badly) until I stopped spraying oil. Your oil slick and smoke
implies that enough fuel/oil is getting into the engine that it is not
all being burned.
2) What would cause this and why would the throttle and kill knob be
ineffective in re-establishing control?
There are various moving parts inside the fuel injection pump that
control how much fuel is sent to the injectors. There is also a governor
that maintains constant speed at constant throttle and limits maximum
speed. Some governors are completely hydraulic, others may be in part
electrical. It sounds like something stuck inside your injection pump
for a while and is now operating "normally". I use the quotes because if
something did stick once, it may well stick again. The operating
clearances inside an injection pump are a few ten-thousandths of an inch.
3) I failed to mention that the fuel was treated with "Store and Start"
in the fall and "Fresh Start" this spring (tank is 2/3 full).
Would this have any bearing on this problem?
Dunno. Fresh fuel is always better. Do you have a water separator in
your fuel system? Have you used biocide to prevent algae growth? It
doesn't take much water, varnish or algae scum to cause problems.
4) What steps should I take to prevent a reoccurance of this problem?
Call a good Yanmar mechanic and discuss this with him/her. If the
problem is in the injection pump, it may be time for cleaning and
overhaul.
5) Given that the fluids, mechanicals look ok and that the engine has
been staticly run for a length of time, should I assume that
nothing has been damaged?
Not necessarily. The damage may take a while to become evident. It took
several months to a couple of years (depending on which cause you
believe) for either the sea water up the exhaust or overheating to seize
our piston rings.
Many thanks for your inputs.
You're welcome. Usual caveat: They're worth what you paid for them. My
recent traumas with my diesel only remind me how very little I know.
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| 1876.2 | Think of it as TURBOCHARGED | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 16:39 | 31 |
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Note 1876.2 Runaway diesel! 2 of 11
HPSRAD::HOWARTH 21 lines 10-JUN-1992 10:00
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At one time I had a 12 YGM (ro something like that) in my boat,
a Hunter 30. It was grossly under powered! But, one day I changed
the oil and put in slightly more than the was required by the
mark on the dip stick. Result-- runaway! But I
put the boat in gear and let it run around the harbor until it
stalled. I didn't see how the engine could damage itself while
swinging a 13" prop especially with a logarithmic power to boat
speed equation.
I would have tried putting something over the air intake
or use the decompression lever but I was alone on the boat. Looking
back, it was exciting and I'm glad I no longer have that pig
powering my boat.
Incidently, I have witnessed a diesel generator jump into a
runaway situation. Something you want to get away from. Pieces
flew from various sides of the engine just before it stopped.
Joe
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| 1876.3 | | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 16:39 | 22 |
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Note 1876.3 Runaway diesel! 3 of 11
RTL::LINDQUIST 13 lines 10-JUN-1992 13:20
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RE .-1
My diesel Dodge pickup has a decal located near the air
cleaner indicating the location for emergency shut down.
This is done by discharging a fire extinguisher into the
air intake.
I would think that if you used either a halon or (for
the enviornmentally sound) carbon-dioxide extinguisher,
you could stop the engine with no additional damage.
- Lee
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| 1876.4 | reply lost | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 16:57 | 0 |
| 1876.5 | Similar Circumstance with .2... | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 17:07 | 17 |
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Note 1876.5 Runaway diesel! 5 of 11
LANDO::STONE 7 lines 10-JUN-1992 16:25
-< Similar Circumstance with .2... >-
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Again, thank you for the information. .2 provided me with some
insight. I too changed the oil and put a little too much in (it's
about a 1/4" over the top line on the dip stick). Could this have
caused it? I have a call into Mack Boring. Will let you know what I
find out.
Thanks
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| 1876.6 | JMHO | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 17:07 | 48 |
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Note 1876.6 Runaway diesel! 6 of 11
FSOA::SLIEKER 38 lines 10-JUN-1992 17:00
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Ah yes Runaways. I had a diesel truck runaway once when the
turbocharger seals let go at about 60 mph. All of a sudden
it felt like I'd been hit in the back by something. By the time
I realized what was going on I was passing through 80 mph in
a cloud of black smoke you wouldn't believe. I got on the brakes
and when they started pushing clouds of white smoke out of the wheels
and fading I figured I was in deep do-do. It turned out that the
heat was so intense that it started to boil the brake fluid so they
started locking up by themselves. I didn't dare put it in neutral
because I was concerned about shrapnel from the engine exploding.
With any non-positively coupled diesels I'd keep a CO2 extinguisher
handy just in case. Diesels can get lube oil into the combustion
chambers in two ways that can result in a highspeed runaway, through
the crankcase breather and past the rings. One of the interesting
points about runaways is that with lube oil containing about 30-50% more
BTUs per pound in latent heat energy than diesel fuel they develop
30-50% more power than if fed with DF, possibly a factor in my brake
overload. Letting a motor run if its loaded can result in destruction
of the motor since the lube oil is consumed rapidly, I used a gallon
in less than 3 miles in the truck. In a boat pull the compression
release or throttle the air immediately. The reason your "throttle"
didn't have any effect is because it isn't a throttle its a governor
high speed limit control. Diesels speed and power are controlled
almost indirectly by setting the high limit of the governer in the
injection pump. The governors are either centrifugal or hydralic and
limit the max speed of the engine. When you advance the power lever
the pump pushes a certain amount of fuel within a range based on the
delta between the actual speed and the governor limit. At the high end
fuel volume wise the engine may no be able to burn all the fuel and
pushes black smoke, this is called over-fueling and should be avoided
since it doesn't produce any more power. The mechanical metering in the
pump is designed to reduce the amount of fuel pushed as the actual
speed approachs the governed speed. The power and speed of the engine
is controlled entirely by the metering of the fuel. As the load changes
(assuming the power lever position is static) the delta speed changes
and the governor automatically adjusts the fuel quantity and timing.
The operator in effect doesn't contol the engine he only sets the
high speed governed speed...
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| 1876.7 | | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 17:07 | 17 |
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Note 1876.7 Runaway diesel! 7 of 11
EPIK::FINNERTY "The bug stops here" 8 lines 11-JUN-1992 13:39
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re: -.1 yikes!
I gather that the locked up brakes locked in the engaged position, and
that's what stopped you?
/jim
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| 1876.8 | | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 17:07 | 19 |
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Note 1876.8 Runaway diesel! 8 of 11
FSOA::SLIEKER 10 lines 11-JUN-1992 16:57
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Thats right, it was weird, first they faded and then they started
locking up. It was so hot in the wheels I expected to see either
the grease cap of spindle seal on fire when I got out, luckily not.
The braking system is closed with a one way check valve feeding the
master cylinder from the reservior. If the fluid boils or expands
enough to push the peddle all the way to the top of travel and keeps
going the only other thing to move is the caliper. Thats what happened.
Took about 45 minutes to cool down enough to move. The rotors warped
pretty badly and had to be replaced they were so far out of true.
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| 1876.9 | Mack Boring's Inputs | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 17:07 | 29 |
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Note 1876.9 Runaway diesel! 9 of 11
LANDO::STONE 19 lines 12-JUN-1992 09:12
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Hi, I thought that I'd get back to you with what I have learned. I
talked with a Pat Donovan (very helpful) at Mack Boring. I briefly
related to him my experience and his first question was, "have you
recently changed the oil?". Yes, overfilling the oil does indeed
cause this condition in that there is a breather tube which carries
the excess into the intake manifold. The solution? Drain the oil
to the proper fill line. He stated that this is very important in
sailboats where the angle of heel will affect the relative oil level
will be different-so be careful when under power.
He also had another IMPORTANT piece of information. In a runaway
condition, do NOT attempt to stop the engine with the decompression
valves. Given the speed of the engine (the pistons) you WILL bend
or break your valve stems as that the pistons will hit the open valves
at the top of the cylinder. He rocommends covering the air intake and
even suggested using a plastic bag. If it gets sucked into the intake
it will be stopped be the air cleaner.
Again thanks for the inputs.
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| 1876.10 | Some diesels have a kind of failsafe | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 17:08 | 41 |
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Note 1876.10 Runaway diesel! 10 of 11
MR4DEC::DCADMUS "happiness is a bigger boat" 31 lines 12-JUN-1992 13:57
-< Some diesels have a kind of failsafe >-
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Some diesel's have a system which allows you to control the air flow.
I've had two MB diesels over the years- a 180D (this was basically a
forlift engine in a car!), and a 200D. the governor in the injector
pump was set by a cobination of engine vacuum and thrittle position.
I had the diaphram go in the engine driven vacuum pump and this allowed
crancase oil to literally get pumped into trhe intake manifold. When I
saw all the smoke, I panicked , as I expected a runaway, as I had seen
in some GM diesels. Fortunatley, The Vaccum portion of the governor
in the pump was set by ther vaccum from the intake manofold , which had
a simple throttle plate intalled in the inlet tube just nelow the air
cleaner. THis was operated by the acellerator pedal.
Taking one's foot of the throttle closed this plate which shut off the
airflow.The idle speed was adjusted by adjusting the throttle plate
position. Seemed like a simple, fool proof approach.
BTW, I lost over a quart of oil in the time it took to slow down from
about 60 to a top. The engine idled nicely, but somewhat must have
thought I was fogging for skeeters. The pupose of the vaccum pump
(cvommon on most automotive diesels) was to provide a source of vaccum
separate from the intake manifold to prevent erratic running when the
brakes were applied or to prevent runaway in the event a vacuum hose
broke.
I seem to remember on some of the trucks we had in the miltary that
there was an "emergency stop" that allowed you to close off the air
intake from in side the cab. That's the only way I know of to stop a
runaway diesel aside from self-destruct (can be interesting in a boat to
watch all them parts exit through the hull!)
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| 1876.11 | Don't get too close. | UNIFIX::BERENS | The Moderator | Mon Jul 06 1992 17:08 | 51 |
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Note 1876.11 Runaway diesel! 11 of 11
HYDRA::ALLA 41 lines 12-JUN-1992 14:04
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Be careful on runaway diesels. Yup, you can stop them by blocking
the air intake however you are now in CLOSE to the engine that may or
may not start coming unglued right next to you.
I happened to a friend of mine, though it was a larger engine, the
port ships generator on an "Old" LST (Landing Ship Tank)
He was the engineering officer on this bucket that had been pulled
in for cargo duty in Vietnam. The ship stopped at our base to resupply
us and he gave me a tour of the ship. Scottie commented on the
problems he was having with that engine when we went though what was
a small space built to house the generator. (it sounded rough, by
now it was 1968 this ship had been built in 1943 and had been run
hard for 10 years)(plus a slapdash layup when she was pulled out again)
Next time the ship was back, about a month later, I stopped over and
he was no longer on board. Seems the generator started to runaway and
as engineering officer he ran to the generator room just as the watch
came running out, (something like "don't go in there ...)
He went in and it blew, almost took his arm, and he was medevaced out.
(he kept the arm, but lots of hospital time, ironic since he had been
on the Liberty the year before when the Israelis attacked it and came
out of that in one piece)
I would rig a CO2 bottle next to the intake with a remote pull or a
piece of metal that pulled over the intake for such times.
Over reving a diesel cuts the life way down, just a function of how
high and how long.
Run the diesel with the new load of oil and when you change it send
it off for analysis, to see what may or may not be abnormally wearing.
On the PBR patrol boats we had GM 6V53's, 220hp V-6 truck engines, SOP
you had a runaway/fire, lift the engine cover a bit and toss the
uncorked fire extinguisher which usually did the trick.
Regards
Frank
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| 1876.12 | Don't use Halon | DPDMAI::CLEVELAND | Grounded on The Rock | Thu Jul 16 1992 20:48 | 9 |
| If I remember my reading correctly, the suggestion of setting off your
halon to stop a runaway diesel is not a good one as it simply creates
more of the same problem. That's one reason why you kill that engine
immediately if your halon goes off. C02 is ok.
If this is wrong, someone please update. As I said, I'm going from
vague memory of reading.
Robert
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| 1876.13 | Halon | SALEM::GILMAN | | Fri Jul 24 1992 13:20 | 5 |
| "Creates more of the same problem" What does that mean? I guess it
means it doesn't work... stop the diesel, right? If Halon will put
out a fire why won't it stop the combustion in an engine?
Jeff
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| 1876.14 | High octane Halon | DPDMAI::CLEVELAND | Grounded on The Rock | Mon Aug 03 1992 17:49 | 5 |
| Jeff,
I'm going to look this back up, but if my memory serves me right, you
got it. It won't stop the engine but causes the engine to go into an
high rpm mode while burning this stuff and spewing an awful smoke out
the back of the boat.
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