Help ASAP Please (Gas in diesel engine)

> wrote in message
ups.com...
> Just to offer a bit of science perspective, I thought that diesel fuel
> was used with diesel engines mostly because it is cheaper.
>
> Otherwise one could be injecting gasoline into the cylinders, and it
> would still burn up. The ignition is based on temperature, and not the
> spark.

Apparently direct injection of gasoline presents a bit of a different
problem than injection of diesel.

I have been of the impression, perhaps falsely, that since diesel
uses compressive heating to fire the charge, the timing of the
burn is heavily dependent on the properties of the fuel. If true,
then the gasoline might ignite much advanced to what the diesel
might do. That could be a problem.

Lubrication of pumps, etc, which diesel fuel would provide would
certainly not be the same for gasoline.

We had an old diesel forklift at our warehouse Scotland. In the
winters, which were bitterly cold, the previous crew had resorted
to ether starting fluid to start the thing. A mechanic later told us
that, once ether had been used, the combustion was so advanced
that the crankshaft had actually been bent, making starting with
diesel a problem. Truth or legend? Dont know. Maybe others
here can comment.

wrote:

> Just to offer a bit of science perspective, I thought that diesel fuel
> was used with diesel engines mostly because it is cheaper.
>
> Otherwise one could be injecting gasoline into the cylinders, and it
> would still burn up. The ignition is based on temperature, and not the
> spark.
>
> The only issue is that gasoline viscosity is lower than diesel fuel,
> and so some components may not be designed for that.


That's ONE issue. There are others, the prime being that gasoline is a
much poorer lubricant than diesel. But there are still others- whereas
gasoline engines require gasoline that is resistant to self-ignition in
order to avoid detonation, diesels need a fuel that WILL self-ignite
immediately upon injection. If it doesn't, it accumulates in the
cylinder and then detonates rather than burning smoothly, causing a
phenomenon very similar to detonation in a gasoline engine.

wrote:

> > wrote in message
> ups.com...
>
>>Just to offer a bit of science perspective, I thought that diesel fuel
>>was used with diesel engines mostly because it is cheaper.
>>
>> Otherwise one could be injecting gasoline into the cylinders, and it
>>would still burn up. The ignition is based on temperature, and not the
>>spark.
>
>
> Apparently direct injection of gasoline presents a bit of a different
> problem than injection of diesel.
>
> I have been of the impression, perhaps falsely, that since diesel
> uses compressive heating to fire the charge, the timing of the
> burn is heavily dependent on the properties of the fuel. If true,
> then the gasoline might ignite much advanced to what the diesel
> might do. That could be a problem.
>

Thats almost what happens. Since fuel isn't injected until its ready to
burn, you can't really get "pre ignition" in a diesel. What can happen
is that the fuel doesn't light immediately, but accumulates briefly and
then goes off all at once. The timing will actually be LATE, but the
combustion will be more of a detonation than a burn and damage can
result. Proper diesel combustion isn't a flame-front that sweeps across
the cylinder like a spark-ignition engine, its closer to a torch flame
on the tip of the injector during the injection cycle. "Torch" is
misleading, since the injector is designed to create a fan flame rather
than a torch-like pencil flame, but you get the picture.

> We had an old diesel forklift at our warehouse Scotland. In the
> winters, which were bitterly cold, the previous crew had resorted
> to ether starting fluid to start the thing. A mechanic later told us
> that, once ether had been used, the combustion was so advanced
> that the crankshaft had actually been bent, making starting with
> diesel a problem. Truth or legend? Dont know. Maybe others
> here can comment.

Its possible, but I'd expect something like a connecting rod to bend
before the crank would. With starting fluid you are introducing a fuel
into the intake air BEFORE the intake valve even closes (like with a
spark-ignition engine) and therefore exceedingly advance-timed
combustion *is* not only possible, but practically guaranteed in the
higher-compression diesel engine.

> there is nothing he can do now. It is apparently an old car.

That would be the atrium and ventricle of the heart of the problem,
wouldn't it? Any damage that could happen in 10 kilometers has already
happened. The parts and labor involved in looking for internal damage
might get you a good part of the way to an overhaul. And it's an old
car, much though it hurts a person to finally lose a car that has been
giving good service for a long time.

My guess: Remove the gasoline (probably by hand-pumping it into gas
cans) and use it in cars meant for it (mild diesel contamination won't
hurt them usually). Change the filters, and drain the lines if that's
reasonably easy. Idle for a while. Drive in a mild-mannered fashion,
with your cell phone and auto-club card readily available, until you
either build confidence that the engine has survived its ordeal or
conclude that it is damaged and needs major work.

If you're lucky, it'll be fine. If you're slightly less lucky, the
fuel pump might have gotten some accelerated aging. If you're really
unlucky, you get to decide what to do with an old car that has trashed
pistons or con-rods. If you didn't romp on it too hard before
noticing the problem and then nursed it carefully to a nearby garage,
maybe you'll have one of the luckier cases.

--Joe