Hey all,

I've been trying to search the archives looking for my issue, but not having any luck. What i have is, I can prime the motor and get 65 lbs off the drill then go to fire less then 10lbs.

What I've done is replace the o-rings on the fittings of the pump, since they were junk. I did take the oil pump cover off, to clean and look it over. I've replaced to different degree fitting on the back of the pump since I have motor mounts and try to get a loop so it doesn't drain back.

Looking for ideas anyway
Thanks!

When you say you only get 10 psi, is that idle? What idle rpm, lifter, rocker gear, block, oil feed to rockers, pushrods?

HV pump ?? I had a very similar problem. Swapped in a HV pump body and alls good now.

If you have a dual line the oil could be draining back through the front line even though you have a loop in the rear one.

Besides pump volume, knowing the rpm your drill runs at when you see 65 psi will help you figure out what you need. If your drill speed is 1800, rhen that represents 3600 rpm engine speed. If you see only 10 psi at an idle of 1200 rpm, that would be a srill speed of only 600 rpm.

I just looked up the drill speeds of 3/8 corded drills. They go from 2500 to 2800 rpm. If they are bogged down to 2/3 speed, then you are looking at equivelent engine speed of over 3000 to 3600 rpm roughly. Pump speed driven by the drill is half that, or about two to three times what it would be at idle, 1250 to 1400 rpm, normal pump speed at 1200 rpm idle is 600 rpm when driven by the engine.

Hey Greg, yes pretty much at idle, wouldn't go up much at all with raising the rpm.

Indy Sr heads

Roller cam, Harland Sharpe rockers.

I had roller lifters that at max lift would expose the bottom of the lifter bore and pour oil out. The engine had good pressure on the drill, but low when running and would climb slowly with rpm.

PS if I recall, I think I had the lifters in wrong, the tie bar was against the block instead of being toward the cam. (it was 20+ years ago)

Do you have restrictors in the oil lines to the heads? If not, it'll bleed off a lot of pressure w/ those rockers.

Yes I do

Pressure will be lower due to the size of the -12 external lines, but is moving more volume of oil at lower pressures.

I kindly disagree. Unless there is leakage by the pump rotors, or an air leak in the pickup lines and fittings, the rotors will draw a full volume of oil, no matter how big the external lines. Atmospheric pressure will see to it.

Huh ??? Those lines are on the inlet side, what the hell do they have to do with outlet pressure ?!?!?

The statement about the drill speed is important. Its tough to find a drill that turns art 500 rpm. What I do is get the prime with a drill then switch to a speed wrench and turn it by hand. If I can maintain some pressure spinning it by hand then I figure its good to go.

Over 50 years around building engines and never had s problem getting oil pressure with a speed handle and maintaining 50 plus pounds or pressure and back in the day with straight 30 weight oil. No matter external or internal oiling.

That’s with wet pump rotors and a full filter.

Not sure what all is going on with today’s parts.

what roller lifter are you using - are the lifter bores bushed? - I am guessing the lifters are becoming uncovered if you have stock lifter bores

Need a little more information. What is the oil pressure at higher engine speeds with the engine running? At 3000, 5000? You've stated it has oil pressure with a drill motor at these speeds. If it does rise with speed? Then the question is what is different when the pump speeds are similar? What parts are moving and opening a leak path internally? If it were me I'd pull the intake and valve covers. Spin the drill while rotating the motor and watch.
Doug

Good idea. Then be sure and have ar least one lifter at max lift, to see if it is uncovering rhe oil galley hole.

True, sorry for the confusion. I was thinking of my entire oil system. It is all -12 to and from the remote filter mount, to and from the Accusump, to and from the Milodon oil pump and to the external return lines.

Sorry guys for late replies, sorry no clue on drill speed, it's a habor freight that's well over 10 years old.

Is it possible, maybe I put the side cover with the impeller's back in wrong?

The lines feel like the have pressure on them. I will try to prime and spin the motor at the same time.

It's a 21200 milodon pump, I have attached a picture of what the o rings looked like.

That’s not a o-ring fitting. Thats a bulkhead fitting, that could b ur problem.

That o-ring is pretty chewed up. I doubt its your problem but it certainly needs to be addressed. That is the wrong fitting to be using an o-ring on. the fitting should not have threads where the o-ring sits. The threads are whats chewing it up. The pump face looks good - they're usually all chewed up by the rotors.



I don't see how anyone could do that !!



Suction lines do not have pressure !!



Why, it won't make a difference.

Have you had the pan off - any chance the pickup is clogged up?

Please tell me you did not use RTV anywhere in the oil system.