I've read the posts about building up oil pressure after a rebuild. I need advice in this situation.

I just rebuilt the 225 that is in my 64 Dart, and I'm in the process of checking out things before starting for the first time. When I crank the engine over in 25 second bursts, after the third burst or so I can get the pressure up to about 20 psi, but it then trails back downward regardless of what I do and goes back to zero or near zero. This is the case with the valve cover off, plugs out.

I did not prime the oil pump at installation, but have subsequently tried to prime the pump by filling the oil filter with heavy oil. It gets to the 20 psi a bit faster, but still trails off. I even cheated, put the plugs back in, and ran the engine for 30 seconds at a time to see if it would reach pressure in those bursts, and it runs fine, but no pressure.

It is clear that the oil pump is pumping, because with the filter off I get a steady flow when cranking. I'm about to an opinion that although I have no pressure it is somehow "not" the oil pump, although that seems counter intuitive. Any ideas where to trouble shoot next?

thank you all in advance. lots of superior minds at this site.

I recently put a rebuilt 225 in my 71 D100. Sounds like your oil pump is probably primed and working. So with your oil pump working, your main concern is going to be getting the oil to where it would be pumped. That's easy if you've got your valve cover off. As you fill your engine with oil, make certain that you cover your valve train with oil and get a quart down into the lifter area as well. Then you can start it up and see if the oil pressure goes up with the engine running. This method worked fine for me.

Best of luck,

Joe

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Joe Hoppe

71 D100 225 Super Six 727 AT on 2008 Crown Vic CopCar frame

64 Valiant Wagon 225 904 AT 3:23 8.75"

Whoa, whoa, hang on.

Bates, the oiling system will not retain oil pressure after the engine is shut off. Nothing is wrong.

The only way you could completely eliminate dry starts is to weld a suction bung near the bottom of your oilpan with a screen, and run a hose from that to a diesel fuel pump, and run the discharge hose to your oil pressure tap. This is impractical and completely unnecessary, though. It is however used on heavy truck engines and high mileage commercial vehicles.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

Sorry for the confusion. The problem is not that I'm expecting pressure when the engine is off. The problem is that I'm not able to retain oil pressure when the engine is turning over.

Daddiojoe, I think you are right that the oil pump is primed. I've not seen any evidence of oil pressure built up in the oil channel such that it is making it up to the rocker arms.

Maybe I'm over thinking it, but since the oil pressure sensor hole is down low near the pan, I would have expected some pressure since the pump is working. I've drained the oil to see (God forbid) if there is a head gasket problem, but it looks fine. Front and rear seals are tight. This is the 4th engine that I've rebuilt (but first /6) and I've never had anything but pretty immediate oil pressure at initial break in.

With the valve cover off, should I go ahead and start it, manually lubricating the rockers and let it run several minutes, with the idea that it will build up the necessary initial oil pressure?

Sure, go ahead and start it up with the valve cover off. You'll need to adjust the valves anyways.

Best of luck,

Joe

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Joe Hoppe

71 D100 225 Super Six 727 AT on 2008 Crown Vic CopCar frame

64 Valiant Wagon 225 904 AT 3:23 8.75"

Are you CERTAIN you got all the threaded plugs back in their respective holes in the oil system. Don't ask me how I know that that can cause a problem ...

Double check your oil pump relief valve. The pickup tube may also not be sealing correctly and aspirating air in the system. Are you checking pressure right at the oil pump, or the pressure tap at the back right hand side of the engine?

This probably goes without saying, but with the spark plugs out your engine will crank a lot faster and the starter will run cooler.

_________________
I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.