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Thought I was buying a Nissan filter when ordering from Motorsport Auto because they look just like the OEM product with color and characters. Any thoughts on quality of these filters? Also, any thoughts on why the idea of not seeing a Nissan filter under the hood bothers me? Thanks! 

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1 hour ago, Geoff's 240z said:

 Also, any thoughts on why the idea of not seeing a Nissan filter under the hood bothers me? Thanks! 

Adjustment Disorder.

https://www.webmd.com/mental-health/mental-health-adjustment-disorder

We can help you work through this.  Fortunately, I'm married to a psychologist so I no longer care what kind of oil filters are on my cars.

Edited by psdenno
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Yikes, not really sure what was. 

Besides oil wars, folks are having filter wars.  My concern with filters lies mainly with the fact they bypass oil directly to the motor whenever the static+dynamic pressure exceeds a threshold - usually when it's quite cold and oil viscosityis at its greatest.  Unfortunately,  the vid didn't provide anything quantitative to consider.  The reason I am focused there is my motor suffered some fair damage from debris that I believe bypassed the filter.

Sorry, don't mean to hijack your thread, just thought I'd offer up what I  am learning and what there is yet to be learnt 😁

The more you look into something,  the less certain and more confused you become.

I'm thinking our motors need two filters.  The normal OEM style filter, and a second filter for bypassed oil.  If nothing else, one that filters out rocks and birds 😉

 

 

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3 hours ago, ETI4K said:

My concern with filters lies mainly with the fact they bypass oil directly to the motor whenever the static+dynamic pressure exceeds a threshold - usually when it's quite cold and oil viscosity is at its greatest. 

The reason I am focused there is my motor suffered some fair damage from debris that I believe bypassed the filter.

I'm thinking our motors need two filters.  The normal OEM style filter, and a second filter for bypassed oil. 

I disagree with both your premise(s) and your conclusion(s).

How far from the original thread do we want to go? Haha!

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On 6/5/2021 at 10:32 PM, Captain Obvious said:

I disagree with both your premise(s) and your conclusion(s).

Always good to learn. Please explain.

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Well first of all, let me be clear that I'm no lubrication expert, but now that I've got a couple more minutes, let me try to explain a little bit.

First of all, I think the premise that both the static and dynamic pressure are involved is incorrect. Since the bypass valve is around just the filter media, the static pressure should have no effect at all. The only pressure that should matter is the differential pressure across the filter media. Any static pressure should come out immediately in the math.

Second, I would claim that the differential pressure across the filter media (assuming that media is clean) is not high enough to open the bypass valve.

You might say "But what about a cold engine just started then... The cold thick oil would be harder to push through the filter media thereby creating a higher differential pressure across that media". 

And to that, I would say "Yes, but don't forget that cold thick oil would also be harder to push through all the bearing clearances and oil passageways, which would increase the pressure on the clean (outlet) side of the filter, thereby keeping the differential about the same."

As evidence, I would cite the oil pressure gauge. It's on the outlet clean of the oil filter. It's higher when the engine is cold and the oil is thick. And the higher the outlet side, the lower the differential pressure across the media.

And on the inlet side... the pressure into the filter is limited at the top end by the pressure relief valve inside the oil pump.

That's my non-expert take.

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So, as the engine wears the differential grows geater and the odds of a bypass event increase.  But the clearances are greater so the crud will probably just slip through.

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Hmmm. Never thought about it that way, but I guess that would be true. If you push 60 psi oil into the filter and let the other side hang open into a bucket, the bypass valve will absolutely open because the differential would be so high. So if you put a brand new high pressure oil pump on your tired worn out motor...

The question is... "How much oil volume passes through the filter (per unit of time), and how much pressure does it take to achieve that?"

Or turning the question around... "How much oil volume can you push through while keeping the bypass valve closed?"

Fram's PH8A says the bypass valve opens at 12psi differential. How much oil could you push through the filter at 11 psi differential? Enough for even a worn out motor?

Anyone know what the spec is on the pressed-into-the-block bypass valve is? For all I know, it's lower than the ones built into the filters? I took a quick look at at couple FSMs and didn't find any spec. They talked about it, but no pressure spec.

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So, I guess this is where things get interesting.  First, my focus is on the first few moments after startup - not when the motor is in some state of 'equilibrium'.  During that time, I am assuming an oil filter is not full of oil and there is not enough oil residing in all the passages, etc. to be able to impart any real resistance to flow.  Before the engine is started, the differential across the filter media is zero.  As oil begins to flow into the filter, its velocity will impart a force on the bypass valve - albeit quite small I'm sure, but important to at least consider since static and velocity pressures are additive.  As the filter approaches being full, oil will begin to be forced through the media raising the static pressure from zero on the oil entering side of the media.  During those first few moments, the rest of the oil system has not yet filled and offers less resistance to flow than it will after oil has been fully distributed to the motor.  This is all qualitative I know, but bear with me for conversation purposes.  The differential pressure across the media is likely higher in these moments than it would be after the rest of the system is pressurized.  If that differential exceeds the filter's bypass valve cracking pressure, a bypass event will occur.

So, without a pump curve, knowing the flow characteristics of the filter media, knowing the actual behavior of the bypass valve (it is most certainly not a precision device), knowing the engine cranking and idling rpms, etc., there'd likely be a fair amount of guessing as to the extent and duration, and therefore significance of a potential bypass event.  That said, this is an interesting read. 

https://www.machinerylubrication.com/Read/29026/engine-bypass-filtration

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2 hours ago, ETI4K said:

So, I guess this is where things get interesting.  First, my focus is on the first few moments after startup - not when the motor is in some state of 'equilibrium'.  During that time, I am assuming an oil filter is not full of oil and there is not enough oil residing in all the passages, etc. to be able to impart any real resistance to flow.

The filter has an anti-drainback valve that keeps the filter full even when the engine is shut off. No differential pressure even when first starting.

And when you change the oil and put on an empty filter? There's no oil in the filter, so you can't bypass dirty oil. There's no oil to bypass,,, clean or dirty.

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Comments appended:

The filter has an anti-drainback valve that keeps the filter full even when the engine is shut off.  -  True, and it's generally held that silicone ADBVs are considered "better", presumably bc the others do not reliably seal against drainback.  So I am asserting that all oil filters are not full at startup, and in my case specifically, mine isn't.  Further, as far as I am aware, there is no mechanism retaining oil in the filter on its discharge side.  Leaving an engine at rest for an extended period of time (however much that is?) would likely relieve the filter of at least some of its otherwise retained oil.

No differential pressure even when first starting.  -  There will always be deltaP even if the filter is completely full bc the oil galleries are not full and at normal operating pressure at startup, and all filter media (even when new) offer resistance to flow.  Not until the oil system is fully pressurized will the pressure on both sides of the media be close in value.  Is the differential enough to crack the bypass?  I suppose if the filter has done some work and is loaded to some extent, the oil viscosity is just so, the startup rpm is on a steep portion of the pump curve, etc., etc., that it certainly could.

And when you change the oil and put on an empty filter? There's no oil in the filter, so you can't bypass dirty oil. There's no oil to bypass,,, clean or dirty.  -  When the pump picks up the new oil and sends it to the filter to fill it and then distribute it through the motor, the initial differential will likely be at its lowest potential, and not at all likely to bypass.  But consider this.  No oil pan completely empties itself.  There is always residual oil, and in older motors, often some "light" debris in the pan, at the least.  Further, if there is "heavy" debris, like metal pieces, it will rarely be completely flushed from the pan by draining the oil.  Adding new oil one quart at a time during a change may or may not deliver that debris into suspension for pickup by the oil pump.  But, I believe the quick change places pump the oil in quickly.  If that is enough to dislodge debris and get it into suspension, and they start the motor to check for leaks then it's a different equation.  Could any form of debris enter the filter and cause a leak in the ADBV by virtue of becoming jammed at the valve (I've seen this type of problem many times in air and water valves)?

This is getting too speculative, of course, but I am considering all forms of failure as I have a currently unexplained "bypass" event that damaged my motor. 

Of course, there are those who believe paper filters will tear, stamped steel bypass valves fail, and some filters are produced missing the bypass valve altogether.  I guess these would result in a bypass event as well.😁

 

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3 hours ago, ETI4K said:

I have a currently unexplained "bypass" event that damaged my motor. 

How have you determined the cause of the damage?

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For all intents and purposes, the motor was new when I built it.  Block was align bored, decked, cylinders bored.  Head was shaved, valve job.  New pistons, rings, pins, oil pump, water pump and on and on.

Drove the car maybe 10-15K miles before putting it on the rotisserie (1997).  Upon disassembly of the motor this past Jan found hard debris and metal shavings in the oil pan and head.  The oil pump was badly damaged, journals scratched, cam towers worn past use.  Interestingly, the machine shop just told me that one piston/rod was 12 grams lighter than the others which were all within a few grams of each other.  When they removed the pins and weighed everything separately, that one piston weighs 19 grams less than the others.  I'm going off memory here, but I think that is near one half cubic inch of aluminum.  Machinist says the (ITM) piston looks fine.  Hoping to pick up everything from the shop next week so I can see for myself.

I get the oil pump would be damaged, but can't understand how the other parts ever saw debris to damage them.20210428_171342.jpg

 

20210428_171318.jpg

 

20201228_154448.jpg

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The bypass valve in the filter is to allow oil to be supplied to the engine in the event that the filter becomes clogged enough that it can no longer pass oil sent to it by the pump. With the multi viscosity oils of today, on cold startup the viscosity of the oil is low enough that the bypass shouldn’t be opening.

Clogging of the filter media to the point that the bypass opens happens one of two ways.

1. The car is neglected and maintenance ignored for so long that the lubricating oil becomes so fouled with dirt and carbon (carbon is what makes the oil black over time) that the filter becomes clogged and oil can no longer flow through it in enough volume to keep the engine lubricated.

2. A component fails (bearing, piston skirt, rings and ring lands from detonation, etc.), and the resulting debris gets forced into the filter and it becomes clogged enough to block the flow of oil.

In either case, bearing damage will result.

And we all know what happens next.

 

 

Edited by Racer X
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