Oiling Issue - Won’t Hold Prime

After finally getting everything together and getting it on the run stand, I'm not able to get oil pressure from just spinning it over with the starter. I have included two videos, one spinning it over with just the starter and one using a drill on the pump. It basically shows it takes quite bit of speed and time to get things started. I am using a Milodon pan, pickup, pump and a Meiling pump cover-all new stuff. The videos are after three days of sitting. The line from the pan to pump has a curve to it, where it is higher than the pump for several inches. I didn't take the time to measure the pump, but after this I guess that is my next step.

I looked through several threads and this does seem to be a common issue, it just seemed there was no single bullet-line routing, oil filter drainback, pump drainback, air leak, etc. I didn't plug the internal pickup, as the Milodon pump is solid where that hole is thus it shouldn't allow any air flow.

https://youtu.be/Os7D8fHTSQg?feature=shared
https://youtu.be/epGIRQvukyM?feature=shared

The oil pressure gauge is sitting in the middle of instrument panel, you can zoom in on it.

What happens when you spin the drill atfull speed from the start? I guess i'd remove the line at the pump itself after setting. See if it's full of oil. if it's empty drain back is happening. Mine has no loop. Has no issues. Even when the pump gears got chewed up from a broken valve spring. It still primed and had good pressure.
Doug

I installed a simple brass swing check valve near the pan on mine. It was unnerving how long it would take to make oil pressure without it.

Just a thought………
If the anti-drain back valve in the filter leaked a little, would it exacerbate the losing prime situation?

Even when I hit the drill full tilt it will take 4-5 seconds for it start picking up oil.

Anyone have a link or picture they are using for a check valve?

I dont have this problem with my melling pump, but i did with my Milodon oil pump and was told by Best Machine to either switch out the O ring on the end of the snout/shaft for a larger one that will fit or smear a small dab of rtv around the O ring. If the O ring leaks it can suck air. Dont use too much RTV, if it gets into the pump it will snap your oil pump shaft. Just a thought.

I've had several different Milidon external oil systems loose the prime after sitting a short while, 8 hours upto 5 days, others that never lost the prime after I started making my own oil pump to block gaskets that fit around the oil hole to the block and snug against the boss that the oil pump drive fits into.
As far as the O ring on the boss, snout, it shouldn't slide up into the block easily, even with oil or grease on it, it should have to be work and have to be twisted around a little while pushing it into the block

I think I remember reading in the instructions for the pump that said you have to use the included larger o-ring and not a standard one.

Would the motor being tilted forward make a difference? I have my back legs on the run stand a little high right now so the engine actually tilts forward a bit, which in mind should help prevent draining the line.

Cab-do you have any pictures of your homemade gaskets?
What material are you using to make them?

I don’t mind making gaskets, I actually made some .015 intake gaskets for this motor-the Fel-pro material is like $6.00 on Amazon.

At this point I am going to pull the line off the pump to see if I have oil in the line. How much oil should be there? Is it a go-no go situation, where if there is any oil there, then it has to be an air leak situation with the pump?

I have a brand new meiling high volume pump sitting on the shelf, so I would be tempted to bolt it on and give it a try. My only issue there is that the Milodon pump cover (top port) interferes with my Schumaker mounts, which is why I bought the Milodon pump and shaft to start with, plus I hate the idea of having bought $600 of oil pump only to not have it work ($400 pump/$200 shaft).

I have no, repeat NO, experience with remote pickups. But the way you have the suction hose with the loop at the top, is there any way you could route the hose with the loop at the bottom? When I did piping design I always tried to eliminate a high point on a pump suction as it takes a lot of flow to eliminate the air pocket at the top. If this is a stupid comment just ignore it.

Sorry no pics. Plumb this in down near the pan and it will solve your problems. Just be sure to install it in the right direction. At least it worked for me.

https://www.amazon.com/Eastman-Brass-Swing-Check-20425LF/dp/B00GZ3H5JA/ref=sr_1_3?keywords=swing%2Bcheck%2Bvalve&qid=1696080923&sr=8-3&th=1

What Milodon pump number is that? Most have this note:
NOTE: This pump does not use stock Chrysler O-ring around gear set. Special supplied O-ring must be used, also available in system rebuild kit #21590.
I don't know if that is the problem.

I would try a different filter and, if that doesn't help, install a check valve in the suction line.

https://www.summitracing.com/parts/hse-4152-12-1

Quick update:

Pulled the line and there was very very little run out. I pulled the pump and it was extremely easy to pull out of the block. It looks like I used the stock o-ring on the snout, so I used a larger o-ring and made a full gasket to go between the block and pump. I primed it and will try turning it over with the starter tomorrow. If no go, then I will put a Baldwin filter on and it try again. I will likely go ahead and get the check valve.

Thanks for all the help.

No pictures, I bought a sheet of fiber type gasket material years ago, not paper type, that is around .030 thick.
I would use a stock type OEM oil pump to block gasket to trace that on the gasket material and trace the hole to the block bolt holes, cut it out and punch the bolt holes out with a hole punch and then install it with 4 3/8 short bolts with large fender flat washers and then cut out the oil pump snout hole carefully

I fought this issue for quite a while. I did all of the above mentioned tips and tricks. Nothing fixed it. I even plugged the old oil pickup, filled it with RTV and made a custom gasket. Didnt help. I ended up replacing the pickup line, and all the fittings including the one into the pan.

That finally solved the problem. Still dont know if it was a bad fitting, a leaky hose, or something with the pickup????? All i know is now itll sit for days and have oil pressure right away.

If you do that make sure you mount it horizontal with the hinge for the flap up top.

I have always had this problem with my single line setup. Both static and swinging pickups. Had the line above the pump, below it. Run a 51515R wix filter with a drainback. No difference.

I have an accumulator so I never worried about dry starts but when I change oil I have to pull the distributor and spin it at high speed and it still takes a bit to pick the oil up.

I need to go through it next oil change and check some things mentioned here. Because priming it every oil change is a PITA.

Put the drill to it this afternoon and ran it pretty slow, I had pressure within 2-3 seconds running it slow. I went ahead and traded out the filter to a Baldwin, primed it again and will let it sit another day and try again.

What is the trick to getting the intermediate shaft in place? Seems like everytime to go install it, I spend 20 minutes slowing turning the oil pump shaft then dropping in the intermediate shaft only to find I am one tooth off one way or the other. It is like the intermediate shaft doesn’t engage the pump until the shaft is already engaged with the cam thus if the hex isn’t lined up it will not fall the rest of the way in.

Drop the pump drive in. Then turn it backwards so it hops up on the cam teeth. Then back in the forward direction. go back and forth like this. It'll skip a few teeth then drop in. If it's still in the wrong position keep at it until it drops where you want it.
Doug

Get a longer priming rod and use it to turn the pump shaft to were you want it

Is yours a Milodon gear?

If so I have the same problem. Other pump shafts I have used never did that.

I even radiused the bottom of the teeth on the drive slightly with a flat file and it didn't help. Another PITA.

It is the Milodon intermediate shaft, you have to use their slightly (and I mean slightly) longer $200 shaft with that particular pump. I have filed down the edges on the intermediate a bit to no avail. I actually keep a socket and breaker bar on the crank so I can just barely bump it to see if the shaft will fall into place, it really requires two sets of hands. It truly acts like it only has one position that it will fit, so you have to have the gear in exactly the right place-maybe I'm not holding my mouth right. Cab-I am using a longer hex shaft so I can turn the pump gear. I was going to spin it over with the starter yesterday but after 30 minutes trying to get the intermediate shaft in and lined up, I just gave up and spun it with the drill. I have tried to look at everything when it does fall in so I can repeat the sequence but it never seems to work the same way twice.

Same here, I have never had the problem on any other build, but I will say that once it is in, there is very very little slop and I do like that. On my last motor the timing seemed to move around a bit when checking it, and I am now thinking between a little slop in the chain and the intermediate shaft that may have been my issue.

I've fought that problem before. The cam gear has 18 teeth. The intermediate shaft has 6 flats. What is going to happen if you try to move the intermediate shaft 1 tooth? You guessed it, now it doesn't line up with the 6 flats. The easiest way to do it is to loosen the 4 bolts holding the oil pump on and pull it away from the block, now put the shaft wherever you want, then twist the oil pump to line up on the flats and tighten the oil pump bolts back up.

I’m pretty sure that with an OE pump and shaft/gear, the hex of the shaft has engaged with the pump before the gear engages with the cam.

I’ve never had trouble getting the pump drive hex to engage with the pump then cam gear, though I’ve never used the Milodon external line setup

https://www.amazon.com/Eastman-Brass-Swing-Check-20425LF/dp/B00GZ3H5JA/ref=sr_1_3?

I let is sit for two days primed with the Baldwin filter. The first video is trying to prime it with just the starter, which is never does. The second video is after I pulled the distributor and hit it full tilt with the drill (600 rpms). It seems to take 3-4 second for it to build pressure.

https://youtu.be/9Upv_pIEdDs?feature=shared

https://youtube.com/shorts/SODsGh2JH3I?feature=shared

I have the check valve in hand, so do I need to go ahead and install the check valve or is the 3-4 seconds an acceptable situation?



As a side note, I also found a better way to get the intermediate shaft in and lined up easier, all I did was cut a bigger chamfer on the end of the intermediate shaft. Once I lined up the pump, I could then get the shaft to slide in much easier.

I will never use the starter motor to try and turn the motor over long enough before starting it to get oil pressure
That is one of the old time Chevy racers things to do on their motors, not a good thing to try on any Mopar motors

Ok scrap everything I said about the additional chamfer helping in getting the gear installed. This process is extremely frustrating, i realize I can stab it and turn the distributor but the pump has to be in a certain position for it to fall in anywhere. You have to walk the shaft all the way around to see if it will fall in and when it doesn’t you slightly turn the pump and try again. I am averaging 20-30 minutes each time I do it. It seems if the shaft were just a tad longer this wouldn’t be an issue. When looking at the engagement it seems there is room for the shaft to go deeper.

Anyway, primed it this morning with the drill, installed the distributor then spun it over with the starter and it primed instantly. I started putting everything I need to start it so hopefully I will fire it tomorrow.

i have primed engines with a pressure tank i built.
i fill the filter when it's installed, then fill the tank with 4-7 quarts of oil, indicated with a sight gauge/tube on the side of the tank.
the fill cap has a tire fill valve with a 1/8npt fitting in the top. i pressurize the tank to 40-45psi.
the bottom of the tank has a hose with a 1/4npt ball valve and adapter[s] that can screw into the oil pressure gauge tap. quick connect hydraulic fittings are used to keep it a no mess operation.
open the valve and "shoot" the oil into the engine, watching the sight gauge go down until the oil is almost gone, then shutting the valve while there is still some oil visible in the gauge tube.
unhook the tank, install the appropriate sending unit, and fire it up.
instant oil pressure.
just like a "home made" accusump system.
this is just my personal experience. your mileage will vary.

Is the plan at this point to let the motor sit for a couple of days, then start it and see how long it takes to build pressure?

Kinda, I feel like at this point, anything above the starter rpm will cause it to build pressure.

I wired it and put the carb on it today, in order to start it. I spun it over a few times with the starter and it moved the gauged instantly so I felt good about starting it. First hit it back fired through the carb, so I advanced the timing a bit and hit it again. It barely fired so I hit it with a little fuel then the starter stopped engaging. I adjusted the starter position and went to start it again and then it popped the fuse from the battery to the switch. I called it a day at that point. I am assuming it is just a low voltage situation on the battery, so I will charge the battery and likely leave the charger on it the next time I go to start it.

Not to hijack, but I've also been fighting a "losing a prime" issue and here's what I tried to eliminate it :

i. sealed swinging pickup threads and sealed bulkhead fitting to pan side ....no go
ii. replaced pickup to pump lines ....no dice
iii. replaced fittings....nope
iv. oil line loop at pump pump inlet....nada
v. lost the swinging pickup for a fixed pickup....no change
vi. new pump....better, but still took excessive time to prime after a shutdown of 1-2 days
vii. tried different filters......same crap

Lost patience pulling the dist to prime for fireup and lucked upon this at a real good price.....

Wish me luck.

I have been following this post and had planned using an external oil on my 572 street Hemi. I'm now having second thoughts as i do not want those issues with priming every time i want to drive the car. Can an internal pick up be made to work with the 4.500 stroke? Is there a better external oil pan available to avoid these issues?

I use the old style Milodon 21815 pump w/ a stock cast iron oil pump cover b/c I hated the remote filter setup and didn't want the leak prone old style Milodon cover. I've never had an issue w/ losing prime.

Seems like this is more of an issue w/ the newer black Milodon billet pumps?

The first Mildon dual line external oiling system I used in 1971 worked fine No issues ever
The 2nd one had this losing prime problem
The last 5 or 6 builds using the cast Milidon aluminum oil body bodies with the nipple on the front of them work fine also

" I have been following this post and had planned using an external oil on my 572 street Hemi. I'm now having second thoughts as i do not want those issues with priming every time i want to drive the car. Can an internal pick up be made to work with the 4.500 stroke? Is there a better external oil pan available to avoid these issues? "


99% sure the 4.500" stroke will not work with the internal pickup.

I had enough of losing a prime so hopefully the Peterson setup will eliminate the issue. Being able to pre oil it before every fire up is an added bonus.

Its a PITA.

Some have no problem at all and other with identical components have nothing but trouble.

Go figure.

Ok, thanks for answering my question.

Chuck from BEST Machine told me about that Primer/Remote , Probably the best thing you can ever put on a BB Mopar or any engine. Get you a cheap cordless drill with a socket, run it for a minute or so. Even better is to rotate the engine while priming it . Also you really appreciate it at rebuild time because you dont have to pull the dist or anything to pre lube. All around a really great investment for your engine. NO more dry starts ever. I use it every time my car has sat for more than 24 hours

I think the hose liner, neoprene, rubber or Teflon may have something to do with this issue.
I now use Teflon lined hose only on both oil systems and fuel systems, no other type of liner
All the major brands of hoses say that the Teflon line will hose take a lot more pressure and heat than the other types of hose liner due safely
They are stiffer and hold their shape around corners making them a little harder to work with, but they last forever, unlike some of the other type of liners
I try to use the curved hose fittings on the ends that need it instead of the sharp turn hose ends

It seems to build pressure pretty quick once started.

https://youtu.be/yJpK_wKdddg?feature=shared

https://youtu.be/EENWEE6cR9A?feature=shared

I agree with the teflon lined hose, working with suction and heat you don't want the hose collapsing in on itself.

On a side note the small block drivers side head oils when the dampener is at 20 ATDC #6 compression and the passenger head oils when the dampener is 90 degrees (1/4 turn) or 5.693" around the dampener BTDC #1 compression and a big block oils when #6 and #8 are at TDC compression (I forget which head is which). With cam/lifter failures being what they are I like to minimize cranking.

Got the engine on the run stand and it did take 3-4 seconds for it to build pressure, so I have decided to go ahead and install a check valve. Did a quick fit up tonight and wanted some feedback on the routing-just curious about the two 90 degree bends.