Any years Oil filter bypass pressure

[TJ Hopland]

Doesn't seem too crazy to me that someone could have 5 year old used filters around.  For me a year is pretty common, not sure I have gone 5 tho.  For me it always seems when I think of getting rid of them the drop off site isn't open.  Its not open every day and I think only one weekday after 4 and the Saturday hours are short and usually very long lines so I tend to let them and the oil build up till I have to take time off work and go. 

Again I'm not saying I know or can prove or test it myself just thinking out loud but how would it push the element away?  For this lets assume its vertical with the threads on the top.

Its all about surface area.  Sides, the element even if its clogged isn't going to be able to move it up or down as long as its able to hold its shape and not just get crushed so we have to think about the ends.  Lets say the element is roughly 3" in diameter.  For the solid bottom plate that's about 7 square inches.  Lets say the top just has a 1" hole in it and what ever gasket up there takes up 1/4" so there is 1 1/2" that the pressure can't get to.  We take the 7 square inches and deduct the 1.75 inches area of the hole and gasket that leaves 5 1/4" square inches for the pressure to push on.

So since the filter is clogged and or the oil is cold we might as well be dealing with a solid piston. Pressure is equal in the can so each end is exposed to equal oil pressure.  So if we have a well used engine that is only generating 10psi of pressure at the filter the bottom is getting 70 pounds of force on it not counting what the spring is adding.  The top side with its reduced exposed area is only going to get 52 pounds of pressure.  So we got 70 plus the spring, maybe another 5 so 75 psi keeping it sealed against the plate and only 52 trying to move it away.  That means there is still 23 pounds of force trying to keep it sealed in place. 

Looking at the pressures there if it can't flow the most likely failure mode I think would be it just crushes the element to the point it can't seal.  I'm not quite sure how to calculate the are of the element but especially with the pleats there is a lot of area there so if it can't pass through it its going to be applying a lot of force trying to go somewhere.

And again my concepts could be wrong and my math would be even more suspect so feel free to point out errors or flaws in my thinking. 

[bcroe]

Here is my opinion on oil pumps.  All I have seen
have a spring loaded valve that opens to limit max
pressure, and some adjustment is possible.  It will
operate at high rpm but tend to close at lower rpm
or idle, and will tend to close more as engine wear
flows oil easier, oil pressure will be seen to drop. 
Wear may become severe enough that the valve never
sees enough pressure to open. 

A high volume pump does not set the pressure, its
bypass valve does.  If an oil filter becomes clogged,
it may have its own low presure valve for bypassing
oil to the engine.  A filter will always flow oil if
it is not clogged, regardless of oil pressure.  It
does take more torque to spin a higher volume and/or
higher presure setting, so I use a heavy duty shaft
on Olds engines such as the Seville. 

I see higher wear engines as losing most of their oil
pressure at idle, which allows faster wear, and the
process snowballs to wear it out.  For these a high
volume pump can maintain more oil pressure at idle,
avoiding even more wear at that point, extending the
useful life of an engine.  Engines I have had out of
the car usually get a high volume pump. 

I have seen claims that porting out a pumps oil
passages will increase its volume.  But it is a
positive displacement liquid pump, so the above
will not increase the volume pumped.  Bruce Roe

[Cadman-iac]

 That's true Bruce, porting the pump will reduce the resistance to the flow, but does nothing to increase it.

 Rick

[Cadman-iac]

 TJ,

 I think the only way that the oil pressure would crush the filter element is if it was made with no way to move within the can.
 A filter with a spring to keep the element pressed against the base can still be moved within can as the spring yields to the pressure for whatever reason it reaches that point.
 Granted, you probably won't ever see that amount of pressure, as there are two means of relief in the event the pressure is too high. The first being the pressure relief valve in the pump body itself. This just vents off the excess back into the pan.
 The second one is the bypass valve intended to allow the oil to get to the engine in the event that the filter becomes clogged.
 
 This was just something that I had thought about while trying to figure out how to get 100 percent of the oil to pass through the filter in order to capture all of the wear material on a new engine, since the bypass valve seems to open around 15 to 20 psi according to the information I've seen. By blocking the bypass valve, you get 100 percent filtration.
 My thoughts are that in this case, if that filter clogs, that even though it does not have a bypass valve incorporated into it, it will still allow oil to push past the element by pushing it down against the spring, thus opening a small path between the inlet and outlet between the base and the element.
 I'm sure that it would take an extreme amount of pressure, but unless the filter can blows off, the oil will get through.
 Does that make sense to you?

 It's all moot at this point anyway, since I've removed the high-volume oil pump and replaced it with a new stock pump. But I wanted to pose the question to see if I could get an answer.

 Rick

[TJ Hopland]

Anyone else want to jump in on the cartridge moving subject?  I'm really curious now and have myself convinced I can explain that it can't move but I know I can convince myself of just about anything so it would be nice if others could jump in and explain that my logic is sound or if its not what the flaw is so I can not make the same mistake on the next rabbit hole I stumble into.

[Cadman-iac]

  I got a chance to cut open a new Cadillac 51258 oil filter to look at it's construction.
  The filter media has a metal cap on both ends with pleated paper to filter with.
 There's a spacer that it sits against that's about half an inch tall, and a coil spring on the bottom that keeps it in place.
 It does have an anti-drain-back valve under the base piece, which is a formed rubber disc.
 









  I measured the distance from the edge of the gasket to the bottom of the element, which is 3 and 21/32", or 3.656".
 The overall length of the filter is 4.360", and the metal thickness of the can and the element bottom cap is. 018" each.
 So if you take the distance of the element and the base including the gasket of 3.656, add the thickness of the can and the bottom of the element of .018" and . 018", you get a total amount of 3.692".
 Subtract this from the total height of the filter including the gasket of 4.360", that leaves the space for the spring of .668", or right at 11/16". The freestanding height of the spring is. 925", or 15/16".
  I took two pieces of round stock that were 11/16" in diameter and put them on either side of the spring on a postal scale I have, and I compressed the spring using a piece of wood wide enough to reach both pieces of round stock until it just contacted them and measured the force, or weight it took to do that.
 I got right at 25 pounds of force, which is not what I expected.
 I measured the diameter of the element, it's 3.25", and the piece it fits against on the base is 1.75" in diameter, leaving a 3/4" wide area around the element that the oil pressure can push against.
 Now I am not sure how to figure out what pressure it would have to take in order to push the filter element down away from the base, but I know that even at 70 psi, if the oil can pass through the filter that's not enough to cause the element to move away from the base.
 I never passed geometry or anything higher in school, so I can't prove what it would take to do what I think can happen with a clogged filter.
 But does anyone know how to work this out? I think it's possible, I just can't prove it myself. I'd like to know if I'm right or not.

 Thanks for any assistance. Rick

[dadscad]

Hope this helps.

https://www2.wixfilters.com/Lookup/PartDetails.aspx?Part=13350

Above, a Link to your 51258  Wix filter specifications. Your filter is classified as a full flow filter. It does not have bypass capability. It's rated to flow 9-11 gpm.

A filter with a "bypass valve", functions on the "differential" pressure of the filter inlet reading to the filter outlet reading. When the pressure is higher on the inlet of the filter than the outlet, due to the filter element restrictions, the bypass valve opens at the set differential pressure. As an example, If the bypass valve opens at 10lbs differential pressure, it will start to open when entering pressure is 30lbs and outlet pressure drops to 20lbs.

As long as the downstream GPM flow through the filter is within its designed flow, the system pressure can be anything within reason below the burst pressure of the filter canister. The downstream lube system bearing clearances determine the system flow restrictions to create the measured pressure on the outlet side of the filter element. So if the filter becomes the greater flow restriction in the system, the bypass valve will compensate to relieve the restriction of flow.

[bcroe]

The pump picks up oil from the oil pan and
sends it to the filter.  If the system pressure
is high enough (over 40psi on my engines), the
pressure regulator might open and allow excess
unfiltered oil to circulate AROUND THE PUMP. 
A new filter is not going to bypass even with a
high volume pump, which is only like 20% extra
volume. 

The filter bypass valve only sees the pressure
loss THRU THE FILTER, which has nothing to do
with total system pressure, and it will only be
opening to save your engine in the case of a
totally plugged filter.  All oil getting to the
new engine will be filtered by the new filter. 
Bruce Roe

[TJ Hopland]

My guess is cold weather is the main consideration for the bypass design.  I don't think they would have really thought it was worth a lot of effort complicating the design and adding cost to try and make life better for the people that were just going to neglect the equipment. That issue is also easily solved(ish) with an oil change.  Cold weather on the other hand there isn't a lot you can do about that.  Even when clean oil and filters get cold things really slow down.

Anyway back to the just for fun exercise....

Im thinking that the in theory plugged sides won't have any effect on the movement we are concerned about.  The direction we are interested in is the ends.  Since the pressure per square inch is the same everywhere inside the can and on the outside of the element its about the area of what you want to move.  The spring side has all its surface area available for that 10psi to act on so 10 pounds of force per square inch and 7 square inches of surface means 70 pounds of force.  The plate end has the hole in it for the outlet so that area isn't exposed to our can pressure so less area exposed, I can't remember what did I say?  5 square inches? So only 50 pounds of force.

Same stuff going on with a hydraulic cylinder.  With the same incoming pressure the cylinder can exert more force pushing out than it can sucking in.  Reason is on the out direction you got the whole surface area of the piston to act upon in the direction you want it to move.  The other direction part of that surface area is taken up by the rod so less area to push on. 

Lets dump the round shapes and just use squares.  LEts say our piston is a 3x3 grid so 9 units, doesn't matter what the unit is but lets stick to inches.  So 9 square inches.  If we have 1 pound per square inch thats 9 pounds of force.  On the other side we have the outlet hole or rod so we loose that middle block, 8 inches and with 1 psi thats only gonna be able to generate 8 pounds of force so assuming that 1 psi differential is enough to overcome other resistance to movement like in a cylinder the drag from rings the 9 is goona win and its going to move to the 8 side. 

To make the cylinder work you don't let pressure get to the 8 side you would usually vent the 8 side so that your whole 9 psi can work to do the work.  Since our oil filter doesn't have any sort of rings dividing it in half like a hydraulic cylinder its always got to fight that differential so even if we had 100 psi in the can that top can never push harder than the bottom because it will always have less area. In my example there would be 700 trying to keep it sealed and 500 trying to unseal it.  The 700 is still gonna win. 

Even if there was no outlet and the top was a solid plate its not going to move because then the pressure will be even in both directions 70 vs 70 or 700 vs 700.  Now if they made the top plate bigger so there was a solid flange that went out to the edge of the can there would be a lot more surface area and the pressure on the inlet side would be greater than what was in the rest of the can because of how closet this large flange is to the sidewalls maybe then it could move.  You could play with how well it sealed to the walls but there would not be any point to that design since to get the higher pressure you could not flow much and if the goal was to get oil through the filter you would not be doing that anymore.  Hmmm...  maybe a new product idea a crappy filter that wrecks your engine so you have to buy parts or a new car?  Oh wait I think we have those now........   

[Cadman-iac]

Edit: I began this post in the quick reply section by mistake, so I'm adding more piecemeal.

  I guess I should explain it this way.  Hypothetically, if you have an engine that does not have a pressure relief valve in the oil pump, and does not have a bypass valve in the filter adapter, 100 percent of your oil is going to go directly to and through the oil filter.

In this situation, with the filter being constructed with a spring to keep the element pressed against the base and the burst pressure for the can at 345 psi, here's my question.

  If the filter is plugged, wouldn't the pressure move the element against the spring pressure?

I'm asking because they used a spring instead of a bracket or something else that would block the element from ever moving at all.

The use of the spring, to me anyway, implies that it's possible that the element can be moved if the pressure is high enough.

Granted, I doubt that this will ever happen. I'm not blocking the relief valve or the bypass valve.

The 472 has both pressure relief valve and bypass valve. If the bypass valve opening pressure is like the Chevrolet, it's going to open around 15 psi, which means that even though the filter screens 100 percent of what enters, the problem is getting 100 percent of the oil flow to enter due to the bypass valve operating pressure.

The pressure relief valve is a bit different than what Chevrolet used in the small block and big block engines. Chevrolet's dumps the excess oil directly back into the pan, however Cadillac's pressure relief is a recirculating design. When it opens the oil is directed to the intake side of the pump body. Since the pump is external, oil passing through the relief valve has no direct path back to the pan, which means it's not creating a turbulence in the pan but ready to be sent into the filter, or bypass it and into the engine.

Here's a few pictures of the pump from my 472.







The 1st picture shows where the filter mounts, notice the bypass valve.

2nd picture I'm pointing to the top of the relief valve piston.
3rd picture I'm pointing to where the oil from the relief valve is routed. This is the "intake" side of the pump gears.

 Rick

[TJ Hopland]

I think the reason they use a spring is the tolerances don't have to be as good.  IF there wasn't something with literally flexibility everything else would have to be perfect. The can would have to be perfect depth the element would have to be perfect the gasket would have to be perfect.  The depth the cap goes on into the can would have to be perfect.   With the spring they could be +/- a couple millimeters on every part and still be fine.   Could one be made perfect?  I'm sure it could but I bet it would be expensive, way more expensive than just sticking a spring in there especially when in many cases its not even a spring, its just a stamped hunk of metal.   

I suppose heating and cooling expansion could maybe be a slight factor too?  Maybe as it heats and expands it would crush the element slightly so when it cools it may not be tall enough to maintain a seal?  I suppose that much could be taken up in the seal itself?  Or is that a thing and there isn't really a 'rubber' seal at the top of the element?

[Cadman-iac]

  That does make sense. I wasn't looking at it from that standpoint, I figured the spring had to have a bigger purpose, otherwise, why use it.

 That means that if you wanted to get 100 percent of your oil to go through the filter by blocking the bypass valve, it's guaranteed not to get around the element because of the spring. I kept thinking the spring was the weak link here simply because typically a spring will give under pressure/weight.

 Thanks for your input TJ. Sometimes we overlook the obvious.

 Rick

[TJ Hopland]

I do recall hearing about the bypass being blocked as part of 'racing' modifications.  As with many 'racing' applications I don't know about the benefits especially when applied to a street driven car but at least in the context of racing you can assume that the racers could and would do things like preheat the oil if needed.  Average Joe isn't or can't do that on his or her way home from work everyday.   

[Cadman-iac]

I do recall hearing about the bypass being blocked as part of 'racing' modifications.  As with many 'racing' applications I don't know about the benefits especially when applied to a street driven car but at least in the context of racing you can assume that the racers could and would do things like preheat the oil if needed.  Average Joe isn't or can't do that on his or her way home from work everyday.   

 This is true, I have only considered doing this in order to prevent any wear material from getting past the filter and into the engine. .
 This was the whole reason for posing the question about bypass valves and filter springs.

 Since I think we've concluded that the filter does not bypass at all because of the spring, the only thing left is the bypass valve itself.

 I've got to debate this in my mind now before or if I decide to do it. I already know that you can block it on the oil filter/cooler adapter as I tried it to see what's necessary.

 I really appreciate you pitching in with your experience and another point of view. Thanks for that.

 Rick

[TJ Hopland]

I would think preheating things, perhaps the whole engine would help and maybe be practical in the context of an initial break in sort of start up.

I just looked up to see if magnetic stick on heaters are still a thing and they are but dang they have got expensive.  Last time I bought one which was years ago I'm thinking they were like $20,  now $75-100!.  Its one of those tools I have maybe only used a dozen times over maybe 20 years but can be pretty handy.  Doesn't work on a lot of newer stuff since aluminum got common.   

[Cadman-iac]

  Yeah,  back in the 80's I had rebuilt a 283 for my 56 Chevy and I had bought one of those heaters that goes in your lower radiator hose. I loved it, car fired right up and was halfway warm. I loved it, until I got the electric bill! I promptly removed it and it sat on the shelf for 30 some years before I finally tossed it.

[Lexi]

I would think preheating things, perhaps the whole engine would help and maybe be practical in the context of an initial break in sort of start up.

I just looked up to see if magnetic stick on heaters are still a thing and they are but dang they have got expensive.  Last time I bought one which was years ago I'm thinking they were like $20,  now $75-100!.  Its one of those tools I have maybe only used a dozen times over maybe 20 years but can be pretty handy.  Doesn't work on a lot of newer stuff since aluminum got common.   

TJ sounds like interesting stuff for that odd tools thread that is currently going. Clay/Lexi