Engine sits for about a weekend and have no oil pressure.

And it loses prime.
Can't get oil pressure started.
Ran it for about 15 seconds and nothing.
Had to put the priming shaft into the distributor hole and use the drill.
Pressure came right up.
Started right up with 72psi.
6 days later, same thing.
This never happened before.
What causes this to happen?And how do you fix it.
Dual milodon oil lines. It's the new external Black oil pump.

Did you loop the suction lines above the pump, so that there always is some oil trapped and can´t go back to the pan?

Michael

if you slow the drill speed down to as best you can match the "cranking" RPM on the intergear will it prime? I'm wondering if it is bleeding off somewhere from a leak or not priming in the first place, just thinking out loud. Post what it ends up being.

6 seconds on the drill and it's got oil pressure.

wix/napa filter?

It is loosing the seal between the pump and the block or somewhere else allowing the oil in the lines to drain down to the oil pan level. Look very closely at the O rings and oil line fittings and maybe even the lines to fix any problems with them
Are you using the stock type oil pump gasket to the block? If so get rid of that That pump only needs the O rings on the pump body and snout to seal properly

Not this build.
Morosos

I've had 1 small block Melling pumps pressure by-pass piston stick open and have no pressure when cold. Also an old 2.2's pump did the same.
Big block would be easy to check that piston.

X2, a pin hole will break suction.

You have an internal air leak in the pickup system. Very common problem with the old Milodon dual external setup. It is less common problem with an internal pickup but can still happen.

It's the new Milodon oil pump and cover setup.

If it has an external line then that is usually the problem. If it is all internal then you probably have an issue with the pickup tube. Maybe a small crack in the tube or the block is cracked in the threads or something like that. Internal problems are rare but problems with the external lines are very, very common. I stopped using the external line systems because they were such a hassle.

When did this all start ?

You make no mention of that.
Fresh engine build, or been on the road untouched for years or something in between?

read title ,said to myself ..bet its got "Dual milodon oil lines"

Mark

When you have an air leak into the pump, the “loop” makes the situation worse. You now have longer hoses filled with more air than you would with “normal” hoses.
A siphon is a siphon. Stop the air leak and you will lose the siphon.
I went through a season of this with my car. Never an external leak. I had the older cast 2 piece milodon pump. At seasons end, replaced the pump gearset, all the orings, resurfaced the pump cover, and had it hard anodized. (There were some minor radial scratches in the cover)
Never found a clear failed part, but doing this stopped the issue. My suspicion has been that the pump clearances, along with cover scratches, allowed air from the outlet to leak into the inlet. Just my best guess.

Dual external -12AN lines

Take it all apart, clean and inspect everything. Put it back together with plenty of lube and torque everything to the proper specs. If that doesn't fix it then you'll have to try it again until you find the air leak.

the dual swinging pick-ups have issues sometimes. I always used the static dragster pick-ups. that being said i'll be the odd man out here. try a different filter first before dismantling the mechanicals. I've had trouble with drain back on every wix, napa, k&n, and I hate to say but baldwins too. baldwins used to be top notch. the anti-drainback in the wix, etc, etc, doesn't work when the filter is in the horizontal. people will argue this but I doubt most people know or understand drain back. currently i'm using purolator pl30001's without issue. other brands may work too. a $10 test is where i'd go first.

That could work. I use the small Mopar 409 filters on my stuff these days. The little filters fill up with oil faster and they are stronger since they are smaller. Screw one of those on there and see if it solves the problem.

Going to try that.
Thanks
This problem started with this Moroso break in oil filter. Think it is a fine micron filter element.

Never had a problem with Wix oil filters. This just started with the Moroso oil filter.

I have used the Milodon dual line swinging pick up on my Hemi for over ten years and always used the Wix filters . Never a problem.

Mark

I have the exact same problem with my swinging pickup, -12 external line, and Indy Billet Oil pump, and I will try the Purolator one...worth a try.

Mark

the problems that the OP originally layed out are exactly problems I have experienced with filter drain back. the oil will drain out of the filter to the bottom of the threaded connection. that doesn't mean there "couldn't" be an air leak, but I seriously doubt that pressure would pick back up/normalize by mechanical priming if the system wasn't air tight. I've built milodon swinging pick-up engine combo's without issue, BUT the joint where the pick-up swings can leak air if not always covered in oil and that's why my preference is a static pick-up.

Just to mention, I do run a Moroso 3 quart accumulator. Even after turning it on and getting 24 psi out, the pump still won't prime.

You stated this started with a new filter - a Moroso - have you tried another filter yet?
As for the pickup sucking air - how is that possible when the pan’s oil level is above the swinging pickup ?

Also, the greatest contributor to a pump’s inability to prime is too much face clearance. Make sure no difference is a trans pump or engine oil pump. That and too much “resistance” to flow on the output side - hence your reduced micron level Moroso filter.

Been using Mildon systems since the late 60’s and never had an issue with any swinging pickup.

Now that is a weird problem. I've had problems with dual line Milodon systems before but I've never had one that wouldn't prime once the accumulator was turned on. In fact, the best band aid for the Milodon non-prime problem has always been to use an accumulator. I'm thinking that you're going to have to take the system all apart and inspect it closely. You must have something more out of whack than the typical Milodon system.

I had a crack in my internal pickup and it did that.

Andy, I have my 2qt Accumulator providing oil to the back of the block where the oil pressure sensor goes...is there another location that would be better? I have the Indy Blue Billet oil pump on my hemi, and a single -12 AN hose going to an Indy swinging pickup.

Thanks, Mark

this is what I use.

easy and effective

https://www.summitracing.com/parts/...l-sr4yUpfOwXIk6J0V5zKcuqSogaAhBJEALw_wcB

I use the Canton equivalent........

https://www.summitracing.com/parts/ctr-22-565

I've got a Moroso, maybe it is a Canfield, 3 quart oil accumulator I've not taken out of the box since buying it from a local boat racer years ago. I'm planning on using a 12 AN line plumbed into the oil line going back to the block from the remoted mounted oil filter with a male #12 AN T fitting
I did use one of the Morrso 3 quart accumulator on another motor years ago and plumbed it with a #6AN line to the back of the block, but decided since then to use the larger size line plumb into the front of the block instead of the smaller size oil passages at the rear of the BB Mopar blocks

I think I have to reroute my rear -12AN line tomorrow.
Looks like its pitched downward not up.
This might be my problem.
Not sure why I would have plumbed it this way.
Wont know for sure till I get it up on jacks.

Sam post what ends up fixing it. My thought is that your current setup worked fine & now SOMETHING has changed/sprung a leak

Hi Sammy,

I have an all aluminum Indy Hemi...that adapter would kick out the filter into the radiator. My -12 AN line comes straight out the back of the pump and runs on an angle down to the rear pan/swivel pickup on the back of the pan. I will see if I have a picture to post.

Thanks, Mark

I had that problem in the eighties and Kendall green oil cured it. That stuff would cling to anything! Too bad it is gone!!!

Lucas oil has that green thick oil, although it is a 60w, & it is green

Now I'm really baffled.
Got a loop in the line at the back oil line.
Front line goes up and over pump, so that one definitely holds oil in the filter. Tightened up all the fittings again. I was able to tighten them up more for some reason.
I started it up and now only 3 days and it lost prime.
Turned off ignition and turned it on and it took about 20 seconds to get oil pressure.
I did use the oil accumulator and got 25 psi shot into the motor.
But oil pressure did not go up quick enough for my liking.
Wondering if they make a 1 way check valve for the bottom oil line?
Going to try again tomorrow and if I lose prime again I'm going to change out the oil filter back to my trusty WIX.

Sammy, mine does the same with the Wix and Mobil1 filters, and mine does what yours does, exactly. I am now thinking the filter is full, but the oil in the pump drains back into the engine and loses its prime. In the summer heat, I sometimes get pressure right away.

I am thinking if there is a way to prime the engine with the accumulator off of the front of the oil pump...maybe that would work???

Mark

Mark. my oil accumulator sandwich is between the pump and oil filter. When I hit the switch, I'm sure that oil must go into the line I'm going to see if I can raise the rear oil line above the oil pump tomorrow, somehow. I might have to change a fitting or 2 to get the line up. I hate seeing no oil pressure for 20-25 seconds. Never had this problem before.

Anyone running thier motor without oil pressure for 15 to 25 seconds better look at your bearings. Mine were starting to smear bearing material. Your results may vary.

This has been on my mind.
Just wondering if the accumulator might help with this problem?

My bracket car, with two different motors with different dual line Milidon oiling systems hasn't had any pressure problems when sitting for months at a time in the car trailer during the winters here, it has got down to-25F two years ago. I have ran 5w20Wt oil and 10x30 VR1 oil in the car since day one of me racing it 6 yrs. ago
I think I had more issues with straight 50Wt and later with 20W50Wt oil loosing the prime, even with Kendall GT1 20x50Wt oil

Sammy,

I looked at the Indy Billet oil pump today...the pump looks to be cast Iron (Indy part) and the cover is two piece. There is a cover bolted on the pump, then an adapter for the oil filter. On the top of the Oil filter adapter there is a single 1/4" pipe plug on the top. I will call Indy on Monday to find out if my accumulator could or should be plumbed into there???

Mark

Yes that's where I had mine on.
I wish I never switched from Indys pump setup.
Never an issue.
-10an line to the 1/4 port.

Sammy,

Attaching the accumulator to that port, would it prevent the pump from losing the prime? and still pre-oil the bearings?

Mark

Mark. I have my accumulator on a solenoid switch.
When I'm ready to turn off the motor, I rev up the engine to get maximum oil pressure, then turn off the switch.
It will hold my75psi till I turn the switch back on to prime the engine.

You guys have mentioned the shape and angle of the feed line. Does mine look ok? I haven't really had any problems but it takes about 3 or 4 seconds to show oil pressure when I fire it up, but I don't know if that's just because of how long it takes the electric oil pressure gauge to react?
I have a habit of letting the motor turn over for about 5 seconds before hitting the ignition toggle switch just to get the oil moving but I don't know if that's good for a motor or not?
I've done this for many years with no problems but I'm always willing to learn.

The delay is probably the sender, that assuming your using a BB and your taking the pressure reading off of the back of the block, which has to fill all the oil passages up before making pressure
I wouldn't and don't spin the motor over on the starter any longer than it takes for the motor to fire, why do that
I know, it is a old Chevy racer trick

Ok thanks Cab, that's about what I figured.
As far as spinning the motor for a few seconds before hitting the ignition, that's only for the first start of the day(or week), my theory has always been that it would get the oil moving for a few seconds before the motor is fired and spinning really fast, but if you guys think it's completely un-necessary I probably won't do it anymore.

Does the oil feed line look ok in my photo?

That line looks good to me
As far as trying to get a BB Mopar oil system to make pressure don't you think it will make pressure quicker at 800+ RPM running than at less than 100 RPM on the starter
Chevy oil pump with pickup and pump submerged in oil versus a BB Mopar having to suck oil up into the external mounted pump, two different animals

I dont.. you need a hump in that line to act as a trap.. right now your draining about 90% back of what you have

That's what my thought is as well.
How fast do you think it takes for all the oil to drain out and lose prime.
Mines very similar but mine has a little more of a hump.
So far 2 days and I still have prime. Don't think 2 more days will have prime.

That would depend on the clearances.. mainly the pump and the oil level... I use to run a fairly tight radius on the
hump to keep the air volume down to a minimum and try to keep the hump close to the pump(again less air
volume)

Hi Mike,

I do not have hump in the feedline to the pump, as one of the header tubes is very close to the AN -12 hose. I use a 45* fitting at the pump, and right angle at the pickup..

That is why I was asking if I would be better off to run the Accumulator to the fitting on top of the Indy filter adapter, instead of running an AN -6 hose to the back/top of the block.

Thanks for any advice, Mark

I never ran a accumulator so I cant say to that,, all I know is you want a large volume of oil to dump quickly
so you want a good size port... I bought a accumulator but never hooked it up

Minimum of -8an is recommended and I believe the back of the block is NOT advisable to use as a prelube.

Are you talking the oil pressure line supply port.. if you are thats a 1/8" and by the time you put a fitting in it
that would be WAY to small

Mike, I'll make a new line with a 45 degree fitting at the oil pump, that should give a small hump up there to keep oil in the pump. Sound correct?

Try it.. anything to make a trap

I called Kenny at Indy, and he told me to plumb my Accumulator to the top of the Filter adapter, and I did, and no more dry starts! I get oil to the passage ways, and Kenny told me it would reprime the pump. Works like a champ now.

Thanks all the help!

Mark

PS: Mike (Mr_P-Body) -- Randy's (Labratt) car now has a 605CI 1100HP all aluminum engine it now!

Sweet... the car is looking real good..Do I see a glimpse of a injector under there... glad you got your
problem squared away

Hi Mike,

Yes, Holley Dominator EFI MPFI. Works great now, since I went with a Dwayne Porter Solid Roller Cam with 115LSA and 260/268* at .050, and advanced 2*
I went from 4" of vacuum on the Carb Cam (110 LSA), and now idles at 16" of vacuum.

I also went with a Frank Lupo 4L80e Trans and his custom 10" lockup converter. It runs like a beast now!!!

Mark

You sound pumped!

So I went under the car to look at the oil lines and one of my oil lines that come from the back of the oil pump , I have dual lines, goes up and over the center link. Its a very tall slope, almost 90 degrees up. The front oil pump line is the typical 120 degree up over the top line.
Still having issues with oil pressure at startup but it does prime eventually.
My question is, is the vertical slope of that back line causing it to take long for the oil to get up and over the center link?
Thinking about dropping it under the center link.

You need a hump in both lines to act as a trap but you want it small so it will prime quick

There is a hump in both lines but the rear one is severely high. Up and over the center link.
Could this be the problem?

The rear oil pan 90* fitting is straight up 12 oclock.from the swinging pickup. Think this could be the
Problem?

How high does the rear line go up.. you want both line low enough but yet still have a trap.. the
area going up high needs to be reduced
EDIT
you also want the humps close to the pump.. I liked to put the hump the last thing in the line close
to the pump

So I just learned something today. And I just wanted to pass this along to anyone who might have this problem in the future.
1st of all, the problem was the oil pan 90* elbow out of the pan.
I had the oil line going up way high and the 90* fitting was pointed in the 12 o'clock straight up position.
I got under the car today and turned the 90* fitting to to 7 o'clock position and got the line under the center link instead of over it.
Turned the car on not only did it prime right up, I now have almost 20 psi more oil pressure.

Will double check if I lose prime tomorrow but I definitely see a huge difference from what I had to now. I'm pretty happy right now.

The extra oil pressure sounds a little odd. I'm wondering if the pickup inside the pan was tilted at an angle or something.

Sounds like you got it covered now.. good luck with it

It definitely changed for the better. I think that straight up fitting with the high oil line was causing the oil pump to work extra hard and the head pressure was causing the lower oil oressure.

Before the fix, I had 72 psi cold and now I have 88psi cold.
Going to start the car tomorrow morning to see if the prime still works.

Went out today to start the car and lost prime again.
Took a bit for oil pressure to get up to making pressure
Kept the rpms way down but this is not normal.
Once I get oil pressure, it's better than before at 82psi cold.
I dropped the one line down down.
I checked for tightness, changed out oil filter and changed oil.

Car sits and it loses oil pressure
Don't know where to go from here.
.

Take the pump off and inspect it for wear or damages to the scroll and rotor, also remove the bypass valve and spring and check to make sure the bypass vale moves freely in the pump cover, no damages or gunk holding it, same thing on the end of the bypass valve and the seat in the pump cover for damage or gunk holding it from seating correctly
Good luck, your making progress

Cab do you think a -12AN one way check valve would solve this problem?
No room to take the pump out and its brand new .

Do you really need 2 #12 feed lines. I just have 1#10 feed line on my hemi. Even after an oil & filter change my pressure comes right up. The 90* fitting on the pan is about 45*.

I had a guy over this week wanting to replace his Milidon single entry cast aluminum oil pump due to it not having any oil pressure after priming it. He had recently bought this 1972 duster with a 440 motor in it that use to be a "drag race car" that had not been started in several years. He was smart enough to prime it before trying to start it but it loss the prime the second time he tried to prime it again the next day and it wouldn't make oil pressure again using his 1/2 inch electric drill motor. I had one used one and one new one on the shelf, he ask me how much I wanted for it and I told him what ever price Summit sells them for or replace it with another new one. He took it home and looked up the Summit price ($339.95)and then decided to look closer at his, I had told him to look at the bypass valve and spring in the pump cover to make sure there was no debris or gunk holding it open.
It had a hunk of silicone holding it opened Once he clean that out his pump work good New motors make metal while breaking in and it is impossible to keep a new motor to clean while assembling them

Will a one way check valve at the back of the inlet of the oil pump solve this problem?
Getting the oil pump off will be impossible unless I pull the engine. Going to investigate the bypass valve today.

.

You still have too much air volume before it gets to the pump.. 2 -12 lines is a lot

Went out today. Started the car.
One day later and I have oil pressure immediately.

So why do I lose prime in 3 days?
Wouldnt the oil drain out the filter overnight?

Would a check valve at the lower -12an fitting on the pump prevent this from happening?

Do you want to risk the chance of it not opening on the start up... I dont know of anyone running one

That's why I would only use just 1 check valve, the top fitting would be used as a backup and be the primary suction line if the check valve failed.

Wait 3 or 4 days now and see what happens then

Why not take one of the pick up lines off.. keep the flattest line

After rerouting the oil lines, I thought the problem was fixed.
It isn't .
Much better oil pressure but still takes a good 15 to 20 seconds to prime.

Did you ever measure the clearance between the pump cover and the rotors ?

Back on 3/15/2020 you said this all started after installing a Moroso filter.

Did you go back to a filter that never gave you problems?

This problem Started after new Milodon oiling system and Moroso oil filter. Moroso was a breaking fine micron filter but changed it out to a regular Wix racing oil filter and pressure did go up to 82psi from 68psi cold..
Priming issue still the same enough. So it's not the oil filter.

A oil pump has very little draw until it gets oil in it to seal it up.. in your case you started with 2 lines and
at least one line went high.. oil or any liquid will always take the path of least resistance.. keep a
small trap point and dont make the pump work hard.. your pump may be screwed by now

I'm thinking that the oil filter is draining out over the 3 days.
A $40.00 check valve might be the answer.
Going to leave the top line without a check valve.
If this doesnt work, I ordered 2 -12an threaded caps and will try just 1 line to see if the problem goes away.

Most all oil filters have a anti drain back valve.. so does Wix

so my question is, if theres oil in the filter, why wont it prime? I guess the oil out of the pump must be draining back over time.

If you have a trap in the line close to the pump and the pump is in decent shape it will prime..
have the oil line low enough that it has oil in it.... take a pic of the oil line and post it

It's almost exactly like Prosports except my other line goes straight across to the front of the pump fitting.
Not sure why it loses prime in 3 days but not 2 or overnight.

If the gears have excessive clearance the oil pressure will take time. The pups don;t pull well, they push. Have you looked at them? Mine runs a single line, Indy cover, swinging pick up, Wix filter. Never an issue. On my previous car; dual line Milodon with worn pump gears was very slow to build pressure. Either way an accumulator will solve it.
Doug

I just received the -12an check valve and I blow in the end that is suppose to close and seal but it leaks air!
Shouldnt it be sealed tight with no air escaping?

Now I ran water through it and it doesnt hold, all water escapes through it.

Boy does Murphy love messing with you