If this is true then now I am really a convert on startup wear from heavy oil. Flow will be significantly reduced to the engine if the relief valve opens. I'm out to buy more 0w20!!
Oil Pressure Does Not Equal Lubrication
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If this is true then now I am really a convert on startup wear from heavy oil. Flow will be significantly reduced to the engine if the relief valve opens. I'm out to buy more 0w20!!
I've wondered the same thing. I've read Dr. Haas's Motor Oil 101 several times now. Thanks Doc. That has been one of the most interesting and informative things I've read on motor oil. I learned a lot from that. I've got an old '84 diesel Rabbit where the oil pressure is not ideal. It is OK when the RPMs are up and the oil is warm. However, when the oil is up to temp and the engine is idling, my pressure is low. My plans are to replace my oil pump with a higher volume pump, and then see if I can go to a lower viscosity oil (currently 15w-40 HDEO -- would like to then try a 5w-30 HDEO). I personally would only move to a higher viscosity oil if I new that the oil pump couldn't be improved upon and I still had low pressure.
-Bryan
Are you sure this is a positive displacement pump. What you describe fits the charateristics of a centrifical pump. The exception would be if the pressure is so high the relief valve is opening.
Duh yeah it is a Roper positive displacment GEAR PUMP By pass is NOT active it is locked down tight.
bruce
What? Pressure is important, if for nothing more than to force the oil through the engine. If pressure is bled off by large tolerances expecting thicker oil, then there may not be enough flow to get to the valve train. If your heart doesn't provide enough blood pressure, your organs and brain starve for oxygen from a flowing blood supply. Our sprinkler system had a leak and some of the heads on the circuit didn't have enough pressure to water.
Someone correct me if I'm wrong here.
Someone correct me if I'm wrong here.
I don't see the comparison. The flow variables through pipe, orifices, and bearings are all different. Your blending system may also see more head resistance if your raising the fluid more than a couple of feet. The crankshaft will add a centrifugal pumping affect for engines.
While your blending system may give some insight into positive displacement pumps and flow versus viscosity, it's a poor analogy to what's going on inside an actual engine, IMHO.
I would suggest you need a new pump, if you are losing 50% flow. It must be worn out. Normal response for a gear or other positive displacement pump when faced with viscous fluids is to lift the relief valve, and if can't lift then you can burst the casing, or if you are lucky the breaker will trip (if electric driven and set properly) before that happens.
Pressure goes down when visc goes down, ~because~ there is more flow. Right?
my blending pressure head means nothing in that it is all static nothing changes but oil vis and flow and pressure very simple. Just a very large lab bench test but is valid
in simply showing pressure/flow versus viscosity nothing more or less.
IMHO this is just like running an IC engine at a steady speed with at a set oil temp if you did that with a heavy and a thin oil I think you would have the same results I see every day at work.
or not my head hurts over hydarulic and fluid dynamics.
bruce
in simply showing pressure/flow versus viscosity nothing more or less.
IMHO this is just like running an IC engine at a steady speed with at a set oil temp if you did that with a heavy and a thin oil I think you would have the same results I see every day at work.
or not my head hurts over hydarulic and fluid dynamics.
bruce
""Normal response for a gear or other positive displacement pump when faced with viscous fluids is to lift the relief valve, and if can't lift then you can burst the casing, or if you are lucky the breaker will trip (if electric driven and set properly) before that happens.""
or PUMPS LEAKS back over rotors as pressure builds up just as in ALL gear pumps (including IC engine) bye the way pump is new. Never seen a burst anything with a Roper and motors never trip so you guys argue it out I work with this every day so what do I know.
bruce
or PUMPS LEAKS back over rotors as pressure builds up just as in ALL gear pumps (including IC engine) bye the way pump is new. Never seen a burst anything with a Roper and motors never trip so you guys argue it out I work with this every day so what do I know.
bruce
Bryan, that's not a good thing to do. With thinnner oil and higher volume pump with what sounds like worn bearings, you will be flinging a lot of excess oil around inside your engine from the piston rod big ends. That will load up your cylinder walls and your worn piston rings may have problems keeping up.
If you are going to try and keep a worn engine running a few more thousand miles, thicker oil is the way to go.
Also, as long as your oil pressure at operating speeds is OK, don't get too alarmed about idle speed oil pressure.
Thank you for the excellent description and education Titan. I don't find it boring at all.
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Sounds like a reasonable course of action to me(if it is economically feasable or worth your time or labor). If you follow through with this please share your results with us. Discussion is one thing, but nothing beats field experience and expirimentation.
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I would suggest partly right. With a positive displacement pump like the one in the typical engine, yes pressure does go down when when viscosity is reduced. However, flow does not change for all practical purposes (and assuming the relief valve is not operating). The power required to drive the pump will also reduce.
A centrifugal pump is very different (and is more like the garden hose example). As you reduce pressure with reduced viscosity or reducing piping resistance, flow does go up, and depending on the pump curve, power also typically goes up. This is not a good analogy to a car lube oil pump.
Yes, when both are at a steady state condition, your system roughly predicts what happens in an engine. But engines have many more variables that can change. Pump flow rate proportional to RPM, viscosity of oil changes due to viscous heating in bearing, the pumping action of the bearings dependent on RPMs, flow through some orifices are not dependent on viscosity, oil pump relief valve may limit leakage in pump, yet bleeds off flow under certain anyways, etc, etc, etc.
In short, basically I agree, but as I believe 1sttruck already mentioned, the analogy may not hold for all conditions.
I'm done. Happy pumping, bruce.
Bruce, I think I may still have a Roper design guide at work. If I remember I will dig it out and have a look. Yes internal leakage will increase as pressure goes up. But, offsetting that to some degree is the viscosity. If the pressure goes up due to increased viscosity then this tends to reduce leakage. My memory could be failing me, but I think you are only looking at about 5% loss or less when you double the pressure.
got mr thinks tho I will double check the by pass maybe they worked loose?
bruce
bruce
Interesting what you can find on line. Here is the same manual I have at work. I think my original is in better shape than this obviously scanned version of it. Too theoretical for solving your issue with the transfer pump though.
http://www.roperpumps.com/SolvePumpingProblems.pdf
However there is probably enough information in the Curves documents if they have your pump model number listed at the link below. Let me know which model you have, size, and RPM you are running it at, typicals pressures, and I can have a quick look at what your internal slip loss should be.
http://www.roperpumps.com/eng1indu.php
http://www.roperpumps.com/SolvePumpingProblems.pdf
However there is probably enough information in the Curves documents if they have your pump model number listed at the link below. Let me know which model you have, size, and RPM you are running it at, typicals pressures, and I can have a quick look at what your internal slip loss should be.
http://www.roperpumps.com/eng1indu.php
Flow rate through many orifices is not as viscosity dependent as the flow rate through a pipe (tube). However, it may not be valid to equate your sprinkler hose scenario to the complex geometries found in an engine's lubrication system.
Ron roper 3648 running 15 HP motor, RPM on pump about 300.
flow rate with 100 sus oil about 55 minutes into 7K tank or about 128 GPM.
With 1000 SUS oil into same tank same temp about 70 minutes or 100 GPM.
Best guess from plant guys (had to averge what each one say) so I was off on original stated fill time.
Anyway Slip looks to be close to what Roper states in the book It is less than I thought but still is valid I think for at least Roper gear pumps.
Tell you one thing they sure GROWL when pumping 2500 vis bright stock.
bruce
This sorta makes me realize why sludged Audi 1.8ts have their OP lights go on after an oil (filter) change. Flow is lees restricted by the new filter and that drops the pressure ever so slightly from what it was prior.
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