"Mallett, Donald B" <Donald.Mallett@bnsf.com> wrote:
[...]
: One topic not touched on the lack of oil at start up of the engine.
: A few companies make a pre charged type of pre oilier. These store oil
: in a device under pressure until the engine is started and release into
: the engine. Some have incorporated a sensor that if the oil PSI hits a
: low predetermine PSI it will send its pressured oil in to the engine.
: What I've been working on but not getting very far due to unable to find
: a 12v pump that can pump oil and can handle any kind of heat. (Just a
: foot note, using the pump only for pre-starting and not while the engine
: is running.)
It would probably need to be a fairly heavy duty pump also
to be able to pressurize oil up to the 40psi or so you would want
for an engine start. I used a 5 amp, corded electric drill to
spin the oil pump in my Cuda and prelube it when I did a top end
rebuild, and it could barely build pressure on the gauge and
heated up mighty quick; it wasn't really adequate for the job.
(Granted, the oil pump design might not be as friction free
as a standalone pump, but still you are pushing a fairly viscous
fluid up to a pretty decent psi and you're going to need a
fairly hefty pump for that I would think.)
An alternative to a pump may be a simple electric valve and
a pressure tank. Mount a small pressure tank somewhere with
an electric valve on it. (The valve is normally closed, and
opens when power is applied.) Plumb a line from the pressure
side of your oil system to the valve, and put a switch in the
cab for the valve. When you are driving down the highway with
high oil pressure, flip the switch which will open the valve.
This will pump oil from the engine into the tank until the pressure
in the tank matches the oil pressure in the engine. You can
install a gauge if you wanted to, or just have the switch open
for 5-10 seconds to ensure it was up to pressure, then shut off
the switch. Now, when you shut off the engine, the pressure tank
has some oil in it, at whatever pressure the oil pressure was
when you closed the switch before. When its time to start
the truck, hit the switch to open up the valve and pump the
oil into the engine then turn the key. (Obviously, you will
want the valve on the tank wired to a constant +12v source
so that the valve doesn't close when you turn the key to
"start".)
A couple of things that might require more thought on this
method are:
- When the valve is opened to fill the tank, will the pressure
drop too low in the rest of the engine?
- You would need to add additional oil to the engine so that
the oil level doesn't get too low when the pressure tank is
full, but not so much that when all of the oil is in the
engine, the crankshaft is foaming it up.
- You would probably want to keep the line from the engine to
the valve as short as possible, since it will probably drain
when the engine is shut off, so you need to fill it before
any of the oil will reach the engine. (Possibly mount the
valve right near the engine and have the oil line itself
be pressurized along with the tank?)
- Will the relatively small quantity of oil in the pressure
tank be enough, and at a high enough pressure to actually do
any good during startup? If not, another method might be
required, something perhaps like a hydraulic cylinder, with
oil on one side and air on the other. Open the valve on the
oil side and close the air valve and open a vent on the air side
while the engine is running which will pressurize the oil side
of the cylinder with engine oil, then shut the valve on the oil
side. Shut the vent on the air side, and open a valve on the
air side which connects to an on-board air tank. This will
pressurize the air side to 90-100psi or whatever. Then, when
it comes time to start the truck, you open the valve on the oil
side and the quantity of oil gets injected into the engine under
the pressure in the air tank (90-100psi), which might equate to
the 40psi or so that you need in the engine itself. An on-board
air compressor would be used to re-charge the air tank. (A benefit
to this method is that you can use the air tank for other things
like filling tires in an emergency, or plumbing in air horns.) :-)
There may be some other problems also; I haven't really given
this more than 10 minutes of deliberation. :-) It just popped into
my mind so I thought I would spew it out there as some food for thought;
maybe it will spark some more ideas for you.
--
-Jon-
.- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
| '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
`-------------------------------- http://www.jonsteiger.com --'
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