Oil pressure not coming up

No leaks anywhere (yet) so I’m pretty sure no plugs are missing. Here are a couple more shots in case someone sees an installation error. BTW, both pipes had new O-Rings installed that seemed to fit well.

When viewed from this angle, the pickup pipe will have a big air bubble in it, but my thought was that pumping a few quarts of oil thru the gallery should force a fair amount backwards through the discharge pipe and the pump and out the pickup into the sump. Of course some will go into the mains too.

Here’s the pan prior to installation. I don’t think there is a way to block the pickup and still have it go on.

Completely mystified.

Rick

You have pre -lubed the engine, so I would have no problem at all starting the engine: I’d be willing to bet that within five seconds or so you’ll get oil pressure.

Hi Rick…are you not seeing pressure on the guage becaus you still have the garden spray bottle attached…try removeing it and blocking the T piece. …im thinking that pressures from the pump is getting lost in the bottle…Steve…ps is your pressure valve in the filter head open and allowing all the oil to return to the sump…try clamping the return hose

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I’m not recognizing the blue plastic cone aft of the pump? Do you recollect what that is/was?

You cannot prime the pick up that way. Oil pumps are positive displacement.
If you primed the gallery and got pressure, I am surprised cranking did not show pressure.
After changing main seals in the 68, it did take a few trys to prime it.
I would be cautious. It should eventually show something. 5 lbs is adequate.

Truth of the matter is, 1 pound of pressure is sufficient… at cranking speed.

Do I hear lower? Going once …. Going twice… :wink:

Sure, some types of engines run with zero oil pressure and do okay.
Tom

Rick,
You may have already done this…
Have you taken off the oil filter adaptor assembly (that converts to spin on filter)?
It may be worth checking if they machined it wrong or perhaps if assembling it “wrong face in” blocks the oil from the pump.
And while it is off, spin the engine!
Dennis
60 OTS

I recall starting my engine after a rebuild and watching the gauge.

That was the longest 50 seconds of my life.

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Hi Dennis,

Can you share a photo of your 60 ots ? :blush:

That’s the plug I had in the bypass nipple. The camera angle makes it look like its near the pump.

I’ve tried it with the line plugged and the bottle removed. Also with the line completely open to see if anything burbles out.

Ah, I see what you mean. The pump, being positive displacement, blocks the gallery pre-charge from filling any more than a small part of the pump. The suction pipe will remain empty.

I wonder what would happen if I rotated the engine backwards by hand while holding pressure on the gallery. Seems like the pump might work in reverse and perhaps slowly fill the suction pipe.

I have not tried this but it’s worth a look.

You’re probably right (hopefully). If nothing else, I can use the bottle to charge the gallery while I try to start it. It should buy me a bit more run time even in the event the pump doesn’t start working. Basically, I’d be using the bottle as a temporary pump.

Thanks all

Rick

Yup. Accusump makes a device for racing that does just that.
Beware if the pump primes and runs, you may find that bottle grenade. :face_with_spiral_eyes:

I’m not sure what a bypass nipple is. Maybe a 3.8 didn’t have it. There are several plugs which if missing could cause a silent loss of pressure without any exterior oil leak. Mine has a rather large plug in front of the distributor bushing inside the timing cavity. And there is at least one, maybe two plugs behind the oil filter housing. Did these all get replaced?

Should not make a hill of beans difference: if there is oil in the pump, and it’s turning, it will lift oil: every time an engine is shut off, their suction pipes drain back into the sump.

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Keystroke problems!!!

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Filling the gallery is where the oil goes is after it comes from pump through the filter so you may not have forced oil all the way through the filter to the oil pump. The pump is pretty tight tolerances and will likely not allow flow towards from the gallery through the filter-

I am optimistic that taking the whole filter housing assembly off may allow pump priming or might reveal a problem with machining of the spin on adaptor or even a gasket problem.

Dennis
69 OTS

As far as I know, all plugs are accounted for. But I will be pulling the filter housing just to be sure.

Rick

I pulled the spin on adaptor and spun the engine with no joy. Next I pulled the entire housing.

I spun the engine again and got reliable oil flow out the lower hole WooHoo! I re-installed the housing and still have good flow.

So, at least the pump is working. I’m still not sure why it wouldn’t prime until the hosing was removed. But I’ll keep adding parts back and testing.

Rick

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Maybe this is silly and has been covered already in this thread, but how about just removing the oil filler cap and see if oil is flowing after startup…?