351CJ

"Gonzo" <jkedward@stoneturtlesoftware.com> wrote in message
news:1138911188.482919.267270@f14g2000cwb.googlegroups.com...
>I have an 89 F250 diesel with a banks turbo and 60K miles on it. Nice
> truck.
>
> Recently, I was towing 9000 lbs of trailer across the Appalachians, and
> my oil pressure went from the bottom of the "low" of normal to just
> above the lowest mark...way below normal. I immediately pulled to the
> side and killed the engine, but the oil level was fine and the oil
> looked and smelled normal and since there was nothing obvious to fix, I
> finished the trip.
>
> Once home, I replaced the oil sensor sender with a pressure gauge, and
> found the oil pressure to be 30psi at cruising RPM (2500rpm) and
> dropped to 10psi at idle. I changed the oil (15w40 Shell rotella
> before and after the change), and the pressure went to 32psi at cruise
> and 20psi at idle.
>
> The oil pressure sensor is NOT where it was when the truck was first
> manufactured, but is now part of the Banks turbo retrofit: it is
> located at the end of a 1/4" oil supply tube that feeds the turbo.
>
> So, do I have a problem? Is the pressure too low? The guy that drove
> the first 40K miles on this truck used it to pull a big boat, but
> nothing outside the capability of this truck. Could the oil pump be
> going out? The engine runs fine, doesn't smoke, pulls strong. I've
> read the procedure for replacing the oil pump, and it sounds like a big
> job...any other suggestions?
>

Obviously without being there... I will just toss out a few things.

Number one, you are running a true mechanical oil gauge on board correct?
The silly IDIOT factory Ford oil pressure gauge is basically nearly useless.

You realize that working your engine hard, even without the "extra heat"
producing abilities of the banks add-ons, will greatly increase the
temperature of your engine oil, reducing it's viscosity, dropping your oil
pressure. The viscosity of engine oil has a direct effect on engine oil
pressure. Oil pressure is also affected by temperature.

I would suggest that if those are your true oil pressure readings, when hot
and working really hard the working pressure would lie somewhere in-between.
I would certainly suggest you replace the oil pump.

Finally engine oil pressure is produced between the crankshaft, and
crankshaft bearings. If the rest of your oiling system and your monitoring
system is fully functional, you may have to start looking in this area.

Good Luck