440 Oil Pressure

[oldchevelle541]

does anyone know what would have been the factory oil pressure for a stock 440 - 375HP with a standard pressure OEM pump ?

[flyinlow]

Warmed up with 10w-30 oil about 60 psi. at cruise, maybe 30 psi at idle in drive. If you installed a mechanical guage so you read PSI.

[Challenger340]

Mine ran 45 psi Hot at rpm, never went any higher as that is where the oil pump pressure relief valve is set.
and....
Hot at Idle in gear is 30 psi, using 10W-40.

I then switched to 15W-40, same 45psi Hot at rpm.... but the Hot Idle pressure stays higher at 35 psi.

Original, never rebuilt, never out of the Car for any reason, 375 hp 440 Magnum in a 1969 Charger R/T SE. 

[oldchevelle541]

Thanks all.......good to know. I run 10W-40 with a K+N Filter HP-3001. It was 30 psi at idle.  Your feedback makes me feel a little comfortable as I thought it was low.

[John_Kunkel]

Mine ran 45 psi Hot at rpm, never went any higher as that is where the oil pump pressure relief valve is set.

The factory relief valve is "set" higher than that. The reason it wouldn't pump higher than 45 psi is because the demand exceeds the supply. (wear)

[c00nhunterjoe]

What rpm is idle though? Alot of people throw the term "idle" out for comparison but a stock car may be idling at 700rpm and trying to compare their oil pressure reading to my idle reading taken at 1300....... just dont forget that variable.

[Dino]

30 at 800 rpm, 40-45 cruising.  Stock gauge, 10-w40.

[BSB67]

Mine ran 45 psi Hot at rpm, never went any higher as that is where the oil pump pressure relief valve is set.

The factory relief valve is "set" higher than that. The reason it wouldn't pump higher than 45 psi is because the demand exceeds the supply. (wear)

John, I hear what you are saying.  I recall the standard pump spring being "55 psi" and the hemi pump spring "65 psi".  I also remember that back in the day when in unadulterated motors, original factory pumps, and the use of the factory red spring or the black spring (i.e. std verses hemi) that those actuals psi numbers were achieved.  Anything original today likely has a combination of higher oil volume demand (bearing wear), pump wear (lower volume output), relief piston and bore wear (valve leakage) and some loss in relief spring compressive force resulting in lower than original numbers.

However, I assume that the OP and some others that have posted are not actually using a good OEM pump.  They either wore out, or have been replaced as they seem to be the first thing that gets tossed.  Todays replacement pumps are complete POS.  I've got three or four sitting here that I purchased hoping to get one that I though was marginally adequately in quality.  But they don't exist.  Besides the poor quality, the pressure relief components/system are actually designed differently from the original.  I have tested several as well.  As you know, you can tell when you are actually into the spring (verses not supplying enough volume). The pressure on the ones I've tested (both standard and high pressure) are low at least 5 psi from the 55/65 psi and not even consistent from one pump to another.  I'm not saying they don't work, or that people should not buy them.  But if you put one on a decent motor (i.e. not wore out) and your pressure is not 55 or 65, I would look at the pump first.

I've started buying used oil pumps for no more than $5, measure them, and keep the better ones.  I cringe every time someone enthusiastically post that the are or will buy a new oil pump.  My first thought is "can I have your old one"

To the OP.  If you have 30 psi idling in gear you are fine.  If you want your cruise psi to be higher, first try a small washer behind the relief spring.  IIRC, you should not shim any more than about 0.060" as you start significantly restricting the pumps ability to relieve pressure as the spring will bottom out.  Or alternatively, try a high pressure spring.  If neither of these make any difference during high speed cruise, then as John stated, volume delivery or volume demand is the cause.

[Ghoste]

So NONE of the new pumps out there are any good?

[BSB67]

So NONE of the new pumps out there are any good?

I have purchased them from several suppliers, but they appear to be from the same pump manufacturer.  None of them are good from a quality perspective.  They will all work, and no one on this forum would experience any problems with them.

There is truly a misconception in this hobby, that new, or high performance stuff is better, or good.   The reality is that the aftermarket, for what we buy, is mostly low volume relatively low quality stuff.  I guess because I'm very close to the manufacturing industry on a daily basis, it is painfully clear to me.  I could go into great detail on this if you like.

But please, do not take my word for it.  Take one apart and look at it closely and critically.  I think you'll see it for yourself.  Then disassemble an OEM, it will then become even more clear, IMO.  You won't even have to measure anything, it is that obvious.

[Ghoste]

Oh I fully take your word for it and I would fall into that category of thinking that a new Milodon or even just a stock oem style replacement would be up to snuff.  Disappointing but good to know.

[BSB67]

Oh I fully take your word for it and I would fall into that category of thinking that a new Milodon or even just a stock oem style replacement would be up to snuff.  Disappointing but good to know.

I did not buy a Milodon.

[BSB67]

Oh I fully take your word for it and I would fall into that category of thinking that a new Milodon or even just a stock oem style replacement would be up to snuff.  Disappointing but good to know.

Just remembered.  There use to be a guy that was "blue printing" Melling pumps.  Maybe he is still out there.  When you looked at what he was doing to them, it was basically fixing them from a quality perspective.  I think he was also coating the rotors, which would be in addition to fixing them.  But the coating would also to help tighten up the rotor clearances.

[John_Kunkel]

Todays replacement pumps are complete POS.

Sorry, gotta disagree; every new pump I've installed in recent years would exceed the advertised max pressure.

The actual pressure of the relief valve spring is irrelevant if the relief valve can't handle the excess volume the pump produces. IOW, if the excess volume has the relief valve wide open and it still can't bypass the excess volume, the excess volume will translate to higher pressure.

[BSB67]

Todays replacement pumps are complete POS.

Sorry, gotta disagree; every new pump I've installed in recent years would exceed the advertised max pressure.

The actual pressure of the relief valve spring is irrelevant if the relief valve can't handle the excess volume the pump produces. IOW, if the excess volume has the relief valve wide open and it still can't bypass the excess volume, the excess volume will translate to higher pressure.

Well your experience is good info.

And yes, I understand.  And I have seen 110 psi and burst oil filters on cold start-up because the relief valve had spacers.  The piston diameter on the newer pumps are smaller as well.  I Guess the relief valve was just a bad engineering idea.

[flyinlow]

more numbers;

Both of my 440's have Melling HV pumps.  with 15w-50 Mobil One they run about 70 PSI above 2000rpm and about 50 PSI at 800 rpm idle fully warmed up on a hot day. One car has an oil cooler that seams to drop the temp about 25-30 * so that engine has relief limit oil pressure at a slightly lower rpm. of course different oil pressure gauges. 

[c00nhunterjoe]

My basic readings- 15 year old melling hv pump purchased from advance auto for $13...lol. cold start on 10w40- 80psi@ 1300 rpm idle, climbs fast if you try to rev it up so i dont....haha. 40 psi hot. If i try to bog it down to around 850-900 rpm it drops to about 30. Cruises at approx 65-70 psi anything above 2500.
    Changed to 20/50 this season and all numbers have gone up about 10ish psi.

[Challenger340]

Mine ran 45 psi Hot at rpm, never went any higher as that is where the oil pump pressure relief valve is set.

The factory relief valve is "set" higher than that. The reason it wouldn't pump higher than 45 psi is because the demand exceeds the supply. (wear)

No, that is NOT the reason it would not pump higher than 45psi, and 45 psi is where mine was set from factory. They can differ, but that's where mine is.
It makes no difference 10-30 to 20w-50, SAE 30... you name it... 45psi with an external mechanical gauge.

The oil pump is capable of far more Oil delivery as rpm's increase. As soon as mine is revved when hot and held at even 1500 rpm it hits 45psi, and goes no higher, even at 5,000 rpm, so it is in fact the Oil Pump pressure relief open.
Only when revved cold(something I don't do), can I exceed 45psi when the as mentioned relief cannot handle the excess = extra pressure.

If you wish to determine "wear" in an Engine... best way is an Oil Pressure "avalanche" test with a mechanical gauge to look for excessive bearing clearance.
In my engines case all is good... shut it off... drops steadily down to 20psi.... THEN it "avalanches" to zero, which on a BB mopar is pretty good.

In Today's world, no two engines are built the same. You can have a tightly clearanced Engine that will have HUGE pressure with a std Volume pump... and conversley.... and loose clearance Engine that has poor Oil Pressure even with a HIGH Volume Pump.
An Oil Pressure Avalanche Test is about the only way to establish a internal clearances correlation.... done externally.

[Ghoste]

Never heard of the avalanche test, how is that done?

[c00nhunterjoe]

Never heard of the avalanche test, how is that done?

Ive never seen a chart but you check on a normal op temp motor. Shut it off from idle and you want to see it maintain oil pressure with a slow decrease down to it's "avalanche point" which is where the bearings no longer hold the oil pressure and it dumps the remaining to 0psi all at once.
   Think of it like when water pressure is coming out of a garden hose. You have 30 feet of hose with 50 psi water. You shut the hose off, but there is still 50 psi worth of water in it even though the nozzle in your hand is still spraying water. The length of time it takes the hose to maintain a slow decrease in water pressure until it gets to that point where the hose is no longer swollen and the water drasticly changes from the spray to the weak stream is kind of what you are looking for with the bearings in the engine. Its a glorified leak down test.

[tan top]

 just thought I would ad this , for reference !!  its from a 69 Charger FSM

[c00nhunterjoe]

There is no way i can get mine down to 500 rpm....lol.

[John_Kunkel]

As soon as mine is revved when hot and held at even 1500 rpm it hits 45psi, and goes no higher, even at 5,000 rpm, so it is in fact the Oil Pump pressure relief open.
Only when revved cold(something I don't do), can I exceed 45psi when the as mentioned relief cannot handle the excess = extra pressure.

The fact that it won't exceed 45 psi when hot has nothing to do with the relief valve "setting", it simply means that the pump can't deliver enough volume to raise the pressure above 45 psi...IOW, the supply can't meet the demand.

In a low pressure situation such as yours the relief valve likely can handle the volume when cold and the max pressure meets the relief valve setting.

This isn't a low pressure situation, it's a low volume situation.

[Challenger340]

As soon as mine is revved when hot and held at even 1500 rpm it hits 45psi, and goes no higher, even at 5,000 rpm, so it is in fact the Oil Pump pressure relief open.
Only when revved cold(something I don't do), can I exceed 45psi when the as mentioned relief cannot handle the excess = extra pressure.

The fact that it won't exceed 45 psi when hot has nothing to do with the relief valve "setting", it simply means that the pump can't deliver enough volume to raise the pressure above 45 psi...IOW, the supply can't meet the demand.

In a low pressure situation such as yours the relief valve likely can handle the volume when cold and the max pressure meets the relief valve setting.

This isn't a low pressure situation, it's a low volume situation.

45psi hot at rpm is NOT a low pressure situation ? why would you think it is ?

Yes, it is the relief OPENING and dumping, in TANDEM with the old inefficient pump, which is not overcoming the return "port" continuing to build pressure, probably due to the worn stack height dimension on the rotors funneling back into the intake side of the pump.
YOU believe whatever you wish.
All I know is "if" I was worried about it... I could easily remove the relief externally and ADD a washer behind the spring, which even on a worn stack height pump, would increase system pressure.
No point though, the thing runs like a swiss watch at 134,000 miles, No Tics, No noises, No blue even on startup, nada, zilch, not even a main drip, best left alone.

[John_Kunkel]

If you think increasing the relief valve spring tension will increase your hot oil pressure, try it and report back.

Hundreds before have done just that and wasted their time.

[Challenger340]

If you think increasing the relief valve spring tension will increase your hot oil pressure, try it and report back.

Hundreds before have done just that and wasted their time.

If the need arises I will.
Done it before, and I will do it again when required, and Thanks.

Dunno what the "hundreds" did to fail ?... or how they reported back to you that they did ?
But here's what I do.
Read it in a service manual when I apprenticed at a Chrysler dealership back in the 70's.
For used Pumps....
* Remove Pump and dis-assemble.
* Check Rotor/Body "stack height", Polish as neccessary(down to .010")
* Polish grooves out of top plate/filter housing
* Re-install Pump
* Shim relief spring externally as required, until desired pressure reached.

Done it on the Dyno a few times of late as well.... but those were NEW Pumps, so no Stack Height dimension work required... just shim and go.

[ChargerKen]

In any hydraulic system the relief valve is installed so that the pressure in the system can be regulated to a predetermined setpoint. That's why shimming the spring raises the pressure. If you were to shim the spring and the pressure does not increase then you have reached the maximum flow of the pump. Pressure is resistance to flow. Bigger clearances in bearings; equals less resistance to flow; equals less pressure;  if the pump won't flow enough oil to unseat the relief. If the pump will flow enough oil to unseat the relief then shimming the spring will definitely raise the oil pressure.