Oil pressure on start-up

[Floyd]

A known good (Stewart Warner) mechanical gauge fitted directly to the engine and a good ,fully charged Optima 6 volt battery will spin it like crazy and you should see oil pressure within 20 to 30 seconds. Pull the plugs to allow faster rotation. Otherwise something has gone wrong.
My opinion

[G.M.]

You can NOT tell if the oil pump is good by putting the pickup screen in oil and
turning the pump by hand. Even a bad pump will put out a big stream of oil.
As soon as you block the output slightly like the restrictions from bearings etc
a bad pump will stop flowing. This could be from worn gears, end play in the ends of gears to bottom cover or the bypass valve on the pump. I described on this forum 4 or 5 times how to build a simple plastic sleave and run the pump with a 1/2" drill. This way you can shim the spring to get whatever preesure you want. These pumps early and later style will all put out close to 100 lbs. Look up in past posts how to build the test unit. G.M.

[tubman]

G.M.

Thanks for posting this. I have searched the site (including the archives), but can't find what you are referring to. I think I see how it works, but I have a question. Is the hose coming out of the fitting behind the gauge to direct the oil from the pump back to container in which the pump is run? Does it have a restriction in it to simulate the resistance of the bearings, etc. If it is, I think I understand it.

Tubman

[flatheadmurre]

You need an adjustable valve on the return hose.
What you want to see is that the pump can put out X amount of gallons/minute at your desired pressure.

[tubman]

Originally Posted by flatheadmurre

You need an adjustable valve on the return hose.
What you want to see is that the pump can put out X amount of gallons/minute at your desired pressure.

Murre,

You wouldn't have a value for "X", would you?

Tubman

[flatheadmurre]

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It should be able to do about 15quart a minute at 2000rpm in the engine.
If i dig i should have a spec from Melling somewhere...but its probably lost in the book keeping

[G.M.]

Originally Posted by tubman

G.M.

Thanks for posting this. I have searched the site (including the archives), but can't find what you are referring to. I think I see how it works, but I have a question. Is the hose coming out of the fitting behind the gauge to direct the oil from the pump back to container in which the pump is run? Does it have a restriction in it to simulate the resistance of the bearings, etc. If it is, I think I understand it.

Tubman

The plastic "sleeve" is bored on each end a few thousandths smaller then
the OD's of the pump and pushed on the pump. This confines the output
of oil in the sleeve. A fitting is drilled and tapped into the sleeve but can
not extend inside or the sleeve won't push on. A "T" with gauge and a
flexible plastic hose for returning the oil into the oil supply for the pump
pickup. The hose is bent to slow or stop the return flow. When almost
closed you will see close to 100 lbs. The bypass valve on the pump is
adjusted pressure you to what want at 40 MPH. Older pumps do not
have the bypass valve, the pressure is adjusted by the valve in the
front of the valve valley. The pump gear is removed and the pump is
powered by a 1/2" drill. The CW rotation of the drill is the way the pump
runs. Even bad pumps will pump a good supply just by turning the pump
a few turns by hand but as soon as you bend the tube there is no pressure
and the oil just slips in the pump. G.M.

[Bored&Stroked]

Originally Posted by flatheadmurre

It should be able to do about 15quart a minute at 2000rpm in the engine.
If i dig i should have a spec from Melling somewhere...but its probably lost in the book keeping

Just so everybody is thinking the same . . . 2000 RPM at the pump is 4000 engine RPM - it runs at 1/2 speed (via the cam).

[flatheadmurre]

That was engine rpm something like cruise speed.
Heres some specs on melling pumps.
M-19 (Std vol. Pump) Idle 16 psi.- flow 2.12 gpm. Cruse 52 psi. (no flow info.)
M-15 ( HV Vol. Pump) Idle 23 Psi.- flow 2.25 gpm. Cruse 56psi. (no flow info)

[Bored&Stroked]

Originally Posted by flatheadmurre

That was engine rpm something like cruise speed.
Heres some specs on melling pumps.
M-19 (Std vol. Pump) Idle 16 psi.- flow 2.12 gpm. Cruse 52 psi. (no flow info.)
M-15 ( HV Vol. Pump) Idle 23 Psi.- flow 2.25 gpm. Cruse 56psi. (no flow info)

I wonder what weight oil and if up to temperature? Probably straight 30 weight and the engine warm.

[tubman]

An old thread I know, but I'm back in Minnesota for the summer and am back on this engine. I was going to put this Mercury engine in my '51 Ford if it ran good. Well, it had over 100 lbs of compression on all cylinders. This is when I ran into the oil pressure problem. Since I got back. I have pulled the pan off the Mercury and plasti-gaged a couple of rod bearings. Both were at .002 and looked good. Since the Mercury pan and pickup won't work in the Ford, I swapped the oil pump. pickup and pan from the Ford onto the Mercury engine. I did this because the Ford engine always had good oil pressure (it was getting low on compression).

Anyway after all of this. I bolted it back on my test stand and hooked up the 6 volt Optima. After about 15 seconds of cranking, it showed a little over 10 lbs of oil pressure on a new mechanical gauge. I think this is enough that I can attempt to start the engine next week. The Mercury pump is withing spec on end clearance (the only figure I can find in the manual). but it's going in the "Questionable Pile" anyway.

I may really luck out on this engine. Now, I'm going to have a beer and celebrate.

[Bored&Stroked]

Always celebrate - early and often . . . beats the alternative!

[JSeery]

Originally Posted by Bored&Stroked

I wonder what weight oil and if up to temperature? Probably straight 30 weight and the engine warm.

Here is some information from Joe:

"The stock Flathead oil pump is a positive displacement gear type, capable of circulating about 15 quarts per minute under ideal conditions when the engine is spinning at 2,000 rpm (the high-volume version pumps approximately 20 percent more). A recent test at Roadrunner Engineering demonstrated that a stock ’46-53 oil filter with restrictor flows about a quart and a half of oil per minute through a clean filter under meaningful conditions of oil pressure (55 psi), temperature (180 degrees F), and viscosity (15W-40). This means that about 10 percent of the oil pumped by the stock pump goes through the filter under these conditions and the rest goes unfiltered to the engine. Therefore, under these same conditions, I estimate that all the oil in a 5- or 6-quart system is filtered in less than five minutes at highway speeds. Not bad and certainly worthwhile!"

[Kerk]

I can remember using a pre=oil tank where you put oil in the container then add air pressure with the connect hose or tubing connected to the oil pressure sender fitting, At this point turn on the valve and look at the gage. With the pressure showing turn the engine over by hand which should lubricate all pressure points. ON the chevys you can drive the oil pump through the dizzy hole with a piece of rod attached to a drill ! kx