[AT] jd 70 diesel tractor

[charlie hill]

yes John a 2 cycle diesel (Detroit such as a 3-54 up to 8-92, etc) will "run 
away".
I've actually seen two of them do it.  Being a 2 cycle there are no intake 
valves.
Combustion air comes into the engine though "air boxes" on the side of the 
cylinders
via a roots type blower (supercharger).  If the oil control rings on the 
engine get
too worn, engine oil will collect in the air boxes and the engine will start 
to burn it
as fuel.  When that happens the governor can not control the engine speed 
because
it is running on engine oil not diesel fuel coming through the injectors. 
Once it starts
it will suck more and more engine oil into it and the engine will race to 
speeds way
beyond the engines design until it hand grenades.

Charlie

-----Original Message----- 
From: jtchall at nc.rr.com
Sent: Friday, April 25, 2014 9:48 PM
To: Antique tractor email discussion group
Subject: Re: [AT] jd 70 diesel tractor

I read an article in GEM many years ago where this supposedly happened on a
2 cycle diesel pulling a cotton gin, evidently the operator put a bunch of
oil in the crankcase so the machine couldn't shut down or regulate speed.
Never fooled with a 2 cycle diesel so I don't know if it was possible, just
remember reading the article.

My reservation to believing the engine was burning the oil is that it is a
mighty small engine to consume over a gallon of oil in a couple minutes
while presumably idling---even being diesel you would think the amount of
smoke would be tremendous.

If its not leaking externally, leaking into the coolant, or burning it, is
it possible for it to be ponding somewhere in the valve train? Not certain
how the transmission hooks up so not certain if it is possible for the oil
to get into there. Same goes for the pony motor. Is it possible for a seal
on the injection pump to be bad and the oil is being sucked into the pump
and returned to the fuel tank? (OK I'm really reaching with that one!)

John Hall


-----Original Message----- 
From: joehardy at epix.net
Sent: Friday, April 25, 2014 8:36 PM
To: Antique tractor email discussion group
Subject: Re: [AT] jd 70 diesel tractor

Greg, It is probably sucking the oil up past the rings and burning it in the
combustion chamber.  I owned an early VW Rabbit diesel and when the rings
became worn, the engine would begin to run away with its self without
stepping in the throttle because the engine was running on crankcase oil.
My car manual said that if you experienced that condition when in neutral,
get away from the car because the engine  would crank up so fast that it
would blow itself apart. I believe you need the take the engine apart.  Keep
us informed as to what you find....Joe Hardisky, Ryman Farm Dallas, PA
On Friday, April 25, 2014 7:44 PM, Dean VP <deanvp at att.net> wrote:

I


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