No oil pressure at idle

sccachallenger

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You can disassemble the old pump and check clearances, and for a stuck spring if you're interested.
And don’t be surprised if a warm engine at idle speed is a little lower than what you’re seeing.
 
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74 360 dart sport

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No you would not be wrong on that point. Higher RPM would definitely see a reduced pressure if the suction side is restricted. Oil pressure is totally dependent on clearances in the complete system. Since rods have side clearances they are usually not a big factor considering the mains only allow metered flow. Some engines such as Ford FE's allow unmetered flow to the rockers which has always been a pressure issue in those engines. There is simply far too much oil fed there and by restricting it you can increase pressure to the rest of the engine dramatically. On to the rest of the equation. Since rod bearing clearance is a big issue and will make noise lets go on to the rest. If the mains are loose, you will see pressure rise with RPM and fall at steady throttle, if you ease off the throttle and see pressure go up a bit then you have too much clearance there. Cam bearings will lower pressure and there is nothing that will change that short of thicker oil either when cold or hot, hot will be lower. You have 5 feed holes directly to the pump that are letting more oil bleed off around those bearings ALL THE TIME hot or cold. Cam bearing clearance is about as critical as you can get in an engine ! Since the cam spins half the RPM clearances are held much tighter than rods and mains. There is less heat here, and with all those springs pushing in the same direction, depending on engine oil system design, some engines feed oil from the top and others feed oil from the bottom. Those that feed oil from the bottom are less affected than the other way, as oil is fed to the cam journal from the bottom the downward pressure keeps the cam closer to the feed hole restricting bleed off, the other way around gives the opposite affect. The other thing that affects oil pressure is the pump itself, clearances in there, end clearance in the pump/gear assembly, clearance between the gear teeth and then there is the pressure relief valve and spring ! Obviously if the engine is old the pump is worn since it gets all the crap from the rest of the engine first hand from the bottom of the pan before it gets filtered out !!!! Oil pumps are for sure easier to deal with then cam bearings. That should be the first thing to address on any engine that has problems. Just ask a shop tech that has worked on newer LS engines or any other engine that uses an aluminum body pump, AMC, Buick, Toyota, Ford in some cases, there are others but what's it matter. I don't recall seeing a MOPAR with an aluminum pump body. As we all know Aluminum expands more and faster than iron so it starts with too much clearance and gets worse. The result is obvious. GET it out of there and put in a good one. And before you put it in take it apart and check those clearances. End clearance in a pump body is easy to fix and it is the worst worry as oil that flows under those gears is not picked up by the next tooth as well as what gets from one tooth to the next. From that point you can roll in new bearings on the crank but if that isn't enough well you know what comes next. Pull that engine and disassemble it for new cam bearings. Those are your options. Thick oil wastes power!
My engine builder told me if I put a hi volume oil pump in with the original oil pan I would suck the pan dry 360 with original 5qt. Pan is this true after reading this thread and seeing people putting in hi volume pump's
 

Phreakish

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My engine builder told me if I put a hi volume oil pump in with the original oil pan I would suck the pan dry 360 with original 5qt. Pan is this true after reading this thread and seeing people putting in hi volume pump's

I run a HV pump with a stock oil pan on my 360/408. Never have I had an oil pressure problem. 70psi cold idle, 40psi hot idle. Bearing clearances are in the .0028-.0031 range and timed oil to the heads (not a fully grooved cam core).

HV will provide more PSI at a lower RPM than a standard volume or a HP pump. The bypass will open sooner on a HV. Engine masters did a whole episode on oil pumps and comparing HP, HV, super-HV, and aftermarket vane pumps. The absolute highest flowing pump used about 4hp more than the stocker. The HV pump provided higher idle pressure than a HP, the HP provided higher pressure only after about 2k rpm IIRC (pump has to flow enough to get up to bypass pressure).

If built with clearances on the tighter end of stock, I'd run a stock pump. If running more clearance, which is a good idea, a HV pump is a no-brainer. A HV pump can also help a worn or high-mileage stock shortblock.

An oil pump won't suck a pan dry - oil drains back quickly in an engine, and the passages and filter can only hold so much oil - it has to go somewhere and there's few places other than the sump for it to reside. If all the oil is staying 'in the heads' there's other issues.
 

512Stroker

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I run a Melling HV oil pump in my stock block, roller valve train, 340 with the stock 5 qt pan 10w-30 oil - no issues.
40 psi @ hot idle, 65 psi @ cruzing speed
 

Bret Tschacher

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Recently fixed the wiring to my oil pressure switch and was dismayed to find the oil light glowing at idle. I removed the switch and placed a mechanical gauge, and it confirmed. Basically zero oil pressure at idle. Comes up to about 5psi at 1500, and climbs from there. Snapping the throttle got me 40-50 psi.
I changed the oil/filter and it made no difference. (No glitter came out either).

Engine is a overhauled Magnum 360. I hadn't noticed any engine noises that would lead me to believe it had oiling issues. Main and rod bearings replaced and plasti-gauged within specs. Cam bearings were not touched when the lunati roller cam was installed. Oil pump is stock Magnum, I just took it apart to check for scoring on the rotor (looked ok). Summit oil pan and pickup (I didn't use Teflon tape on the pickup threads, was I supposed to?). Stock magnum oil pump drive. Wix 51515 (tall filter) and 10w-30 oil.

Anything I can check before I have to pull the motor?
Why doesn't ANYONE ever bother to check the clearance between the pump gears and case? These gearotor pumps are critical ! You HAVE to check the clearance between the rotor lobes and more so the clearance between the rotors and the pump body cover ! Use you heads people, how is the pump going to build any pressure against the oil if it is easier for it just flow around the parts instead of into the oil galleys and against the pressure gauge? The pump spins half the engine speed so with all those places for oil to bleed off and then add clearance in the pump, what do you expect? The engine doesn't open up more clearance at any time while it speeds up so if you start spinning the pump faster than it stands to reason it will pump more oil and make pressure. Now it only takes a little over 5 PSI to float a bearing and unless you have a very sensitive pressure gauge, you're not going to notice much difference above or below 5 PSI readings. The critical issue is that oil is flowing through the engine parts and since you do see over 20 PSI the oil is obviously flowing. You aren't hearing tappets clatter so there's no issue there. Have a look at a brand new Chevy small block or even an old small block, look at the engine manual specs. Chevy's never listed much over 35 PSI at any RPM and a lot of engines did worse than that. In a properly built race engine, clearances on the crank and rods were usually increased to allow more oil flow to cool the parts. Reason it out the more pressure requires more power to make an puts an added strain on the pump and drive system. The generally accepted rule is to have 10 PSI for every 1000 RPM so if you never spin the engine over 4500 than 45 PSI is fine. Now unless the oil pan is smashed, there won't be a problem with the pickup tube because the strain screen and cover are designed to get the pickup as low as possible in the pan for a reason. There will always be a space for oil to enter the pickup even if the pickup contacts the pan. Even in cases where the pan has been bent and the tube is pushed up, it will still let oil flow in. As far as tape or any sealer on the pickup tube threads, doesn't matter, there isn't going to be enough leakage around the threads to make that kind of difference either. Now with the older small block MOPAR's high oil pressure was a no can do issue because it would blow out the gasket at the filter adaptor plate to the block, unless you were running the angle adapter with the cast housing ! Newer engines run 5W30 in a lot of engines and this oil is always thin so it isn't for making pressure, it's for flowing so don't worry about it. My last comment will be about an old Ford Flathead V8 I rebuilt about 45 years ago. I had to bore out 1 hole for a .020 piston because a broken ring had made a mess of the wall. The rest of the cylinders were fine for a re ring. Flatheads were notorious for cracking blocks and basically were worth putting that much into them. They were so old and hard to find parts for even that long ago, I had to settle for a reman pump and the way those things were designed, wasn't anything a person could do about some of the clearances just like an AMC, Buick, or any other engine with a pump housing cast in the timing cover outside of replacing the cover to tighten up the spaces. The only you could do was to take out end clearance in the cover piece of the pump which is basically all you can do with any pump! Take what you can get where you can get it. Then think back if you're old enough to remember the way things were in the 40's when engines didn't even have a pump to make pressure beyond 15 PSI at the mains and the pans had troughs in them to catch and hold a bit of oil that dripped down from above and when the connecting rod came down and around, a little scooper splashed some oil up into the rod bearing which was about as hard as a piece of soft lead, called Babbit alloy inlays that had to be melted into place and bonded to the rod. Now we all know how easy it is to melt lead so it would be obvious that it would take much heat to trash one of these. Now if you absolutely must have more pressure than pull the engine remove that pan and pump and open it up to check it. Find out what the specs are supposed to be and fix it ! Sand the pump housing and end cover if it is showing wear till you have between .003 to .005 inch between the sides of those gears and the housing pieces and if you have anymore than .006 to .008 between the gear lobes, replace the pump with a new pump and check it before you install it ! Even new pumps can have too much space for oil to leak by. Personally I never cared for using a stock pump in any engine I built, I nearly always went went with a high volume unit if it was available but as I mentioned, AMC's, Buick's and a few others there was no choice. For those I often installed a shimmed bypass system but that never helped for low speeds. Again, high pressure only draws more power and loads down the pump system which costs you some small amount of efficiency. Don't sweat the little things all the time.
 

Rat Bastid

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Why doesn't ANYONE ever bother to check the clearance between the pump gears and case? These gearotor pumps are critical ! You HAVE to check the clearance between the rotor lobes and more so the clearance between the rotors and the pump body cover ! Use you heads people, how is the pump going to build any pressure against the oil if it is easier for it just flow around the parts instead of into the oil galleys and against the pressure gauge? The pump spins half the engine speed so with all those places for oil to bleed off and then add clearance in the pump, what do you expect? The engine doesn't open up more clearance at any time while it speeds up so if you start spinning the pump faster than it stands to reason it will pump more oil and make pressure. Now it only takes a little over 5 PSI to float a bearing and unless you have a very sensitive pressure gauge, you're not going to notice much difference above or below 5 PSI readings. The critical issue is that oil is flowing through the engine parts and since you do see over 20 PSI the oil is obviously flowing. You aren't hearing tappets clatter so there's no issue there. Have a look at a brand new Chevy small block or even an old small block, look at the engine manual specs. Chevy's never listed much over 35 PSI at any RPM and a lot of engines did worse than that. In a properly built race engine, clearances on the crank and rods were usually increased to allow more oil flow to cool the parts. Reason it out the more pressure requires more power to make an puts an added strain on the pump and drive system. The generally accepted rule is to have 10 PSI for every 1000 RPM so if you never spin the engine over 4500 than 45 PSI is fine. Now unless the oil pan is smashed, there won't be a problem with the pickup tube because the strain screen and cover are designed to get the pickup as low as possible in the pan for a reason. There will always be a space for oil to enter the pickup even if the pickup contacts the pan. Even in cases where the pan has been bent and the tube is pushed up, it will still let oil flow in. As far as tape or any sealer on the pickup tube threads, doesn't matter, there isn't going to be enough leakage around the threads to make that kind of difference either. Now with the older small block MOPAR's high oil pressure was a no can do issue because it would blow out the gasket at the filter adaptor plate to the block, unless you were running the angle adapter with the cast housing ! Newer engines run 5W30 in a lot of engines and this oil is always thin so it isn't for making pressure, it's for flowing so don't worry about it. My last comment will be about an old Ford Flathead V8 I rebuilt about 45 years ago. I had to bore out 1 hole for a .020 piston because a broken ring had made a mess of the wall. The rest of the cylinders were fine for a re ring. Flatheads were notorious for cracking blocks and basically were worth putting that much into them. They were so old and hard to find parts for even that long ago, I had to settle for a reman pump and the way those things were designed, wasn't anything a person could do about some of the clearances just like an AMC, Buick, or any other engine with a pump housing cast in the timing cover outside of replacing the cover to tighten up the spaces. The only you could do was to take out end clearance in the cover piece of the pump which is basically all you can do with any pump! Take what you can get where you can get it. Then think back if you're old enough to remember the way things were in the 40's when engines didn't even have a pump to make pressure beyond 15 PSI at the mains and the pans had troughs in them to catch and hold a bit of oil that dripped down from above and when the connecting rod came down and around, a little scooper splashed some oil up into the rod bearing which was about as hard as a piece of soft lead, called Babbit alloy inlays that had to be melted into place and bonded to the rod. Now we all know how easy it is to melt lead so it would be obvious that it would take much heat to trash one of these. Now if you absolutely must have more pressure than pull the engine remove that pan and pump and open it up to check it. Find out what the specs are supposed to be and fix it ! Sand the pump housing and end cover if it is showing wear till you have between .003 to .005 inch between the sides of those gears and the housing pieces and if you have anymore than .006 to .008 between the gear lobes, replace the pump with a new pump and check it before you install it ! Even new pumps can have too much space for oil to leak by. Personally I never cared for using a stock pump in any engine I built, I nearly always went went with a high volume unit if it was available but as I mentioned, AMC's, Buick's and a few others there was no choice. For those I often installed a shimmed bypass system but that never helped for low speeds. Again, high pressure only draws more power and loads down the pump system which costs you some small amount of efficiency. Don't sweat the little things all the time.

Ill read this IF you go back and use some punctuation. If not, I won’t.
 

Sterling

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This is why I take every new pump apart and inspect. This was a brand new pump that the relief was stuck, and I got it less than a year ago

20220915_165758.jpg
 

Bewy

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Post #52. You gotta laugh, haven't you: a HV pump will suck the pan dry. This assumes that the oil passages are not completely filled with oil from using the std pump & that there is room for more oil.
If the passages are not full of oil, then you get no oil pressure............or very low oil pressure....all the time at any rpm.
 

krazykuda

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My engine builder told me if I put a hi volume oil pump in with the original oil pan I would suck the pan dry 360 with original 5qt. Pan is this true after reading this thread and seeing people putting in hi volume pump's


I've been running high volume oil pumps with stock oil pans on my daily drivers for decades and haven't had any problems...
 

krazykuda

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Have you checked to make sure that the oil galley cup plugs are installed that go behind the camshaft thrust plate??? I had a similar problem like this once before and that was the cause, the machine shop didn't put the cup plugs in the oil galleys behind the thrust plate...
 

66fs

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Have you checked to make sure that the oil galley cup plugs are installed that go behind the camshaft thrust plate??? I had a similar problem like this once before and that was the cause, the machine shop didn't put the cup plugs in the oil galleys behind the thrust plate...

Early small blocks did not use plugs since the thrust plate was machined to seal the oil galleries. Somewhere along the line that changed, not sure when. I have a stash of 60's and early 70's engines, none have the plugs in the oil galleries behind the cam thrust plate. I too have run HV, HP oil pumps with stock pans and never had oil issues. Ran a mechanical Stewart Warner oil pressure gauge and the 273 would see 7,000 rpm regularly.
 
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