Any years Oil filter bypass pressure

[Cadman-iac]

  I have a technical question about oil pressure and oil filters.
 Does anyone know at what pressure the typical oil filter will bypass the filtering medium and just let the oil pass without being filtered?
  And if you run a high-volume oil pump, does it cause the filter to bypass the filtering medium if the pressure is too high, even if the filter medium is clean?

 What I'm trying to figure out is if it's worth using a high-volume oil pump, or if this is just a recipe for disaster.
 For example, say you have some debris from something in your oil, whatever the source.
 If you are running a stock oil pump I would expect the debris to go through the filter and be trapped there, preventing any damage.
 But what if you have the same debris in your oil and are running a high-volume oil pump? The debris is pumped to your filter, but due to the high pressure will the filter still remove the debris, or does the bypass spring inside the filter allow the oil to push past the filtering medium and allow the debris to get into the bearings or other areas inside the system and cause damage?

 Would you remove a High-volume pump and replace it with a standard one for this reason? Or just not use the high-volume pump in the first place?

 Rick

[TJ Hopland]

If you are basically doing a stock rebuild and planning on using the engine more or less in its stock application there is no reason to go with a high volume pump.  I don't think it would bypass the filter because that won't be the restriction, the rest of the engine will be the restriction if its stock.  Could actually hurt you because its going to be extra stress and pumps don't like to flow less than they are designed for.  I'm not sure what it takes to cavitate an oil pump but if you did that would be bad for oil pressure.   

If you are changing things about the engine like clearances and the average RPM maybe adding a turbo then you may want and need more oil.   Trying to band aid a trashed engine maybe another reason to go with a high volume pump.

I would guess if you got enough crap in your filter for dirt to be the problem you would have bigger problems so bypassing the filter would not likely be the biggest problem.  I think the more common reason for a filter to bypass would be cold to extreme cold especially before we had the fancy 5w and 0w oils. Thick oil doesn't go through filters.

One other twist is the oil pump is before the filter so if you have any harder materials in the oil its going to damage the pump on the way through and even if you correct other issues pump could be damaged to the point it can't perform as needed.   

[Cadman-iac]

  What I was thinking of was if you have a newly rebuilt engine, you know there's going to be metal from the cylinder walls and rings, maybe also from other parts in the engine as they're breaking in, and it's definitely going to get picked up by the oil pump and run to the filter where hopefully it gets strained out, but is it possible if you have a high volume pump putting out up to 70 PSI for the pressure to be high enough to force the filter's bypass spring to yield, and the oil and whatever is in it to be pumped into the engine bearings and lifters?
At what pressure will the filter begin to bypass is what I'm getting at. And this is with a new filter as well.

Do the filters have to meet a certain specification for this, or is it just up to the individual manufacturers to determine what the bypass threshold should be?

I realize that if the medium is clogged with debris that the filter will most likely bypass, but is it possible to cause a new filter to bypass from too high of a pressure?

If so, is it possible to determine what that pressure is?

If it's a low setting, say 30 PSI or so, I don't believe I'd want a high volume oil pump if it's going to cause the filters to be ineffective.

I also realize that the pumps own pressure relief valve will cause oil to simply return to the oil pan if that setting is reached. This isn't what I'm concerned with. It's the filters bypass system I'm asking about.
Thanks in advance for your input.

Rick

[TJ Hopland]

----slight edit, was going to put this at the end but it looks like maybe its more important than the rest of my ramblings, this may be a case where we (users of non Chev, Ford, or Chrysler engines) are worrying about stuff that just doesn't apply to us----

What engine we talking about?  I just looked up the WIX 51258 which I believe was the PF24 that fit most of the non Chevs through most of the 60's and 70's.  That filter does not have a bypass valve in it but has a drain back valve.  Drainback could be a good thing with a front dizzy / oil pump especially if it was say a 500 in an Eldo where the pickup is at the rear.  
https://m.wixfilters.com/Search/PartDetail?PartID=13350%20&Source=WESR

If you go a little older the 51049 is often listed and looking at the specs for that the biggest difference is that one doesn't have a drain back valve.  Rest of the specs are pretty close.
https://m.wixfilters.com/Search/PartDetail?PartID=154643%20&Source=WESR

Now lets take the 51515 which is most commonly known as the FL1A that like 50 years of almost every Ford and many Chrysler and many industrial applications, possibly the most commonly use filter for classic American stuff... drum roll please..... Bypass valve 8-11 psi.
https://m.wixfilters.com/Search/PartDetail?PartID=193964%20&Source=WESR

I guess I unfairly lumped Chevy into the mix because the 51069 or 51061 which was the PF25 and PF35, basically the classic Chev car and truck filter they do not have a bypass valve.
https://m.wixfilters.com/Search/PartDetail?PartID=157637%20&Source=WESR


So it looks like GM for the most common filters for the era we are most commonly dealing with here didn't do a bypass in the filters. 


--- and back to my usual ramblings which may be even less useful now---

I would imagine there was a spec for the filters but when you watch video and see pics of tore down filters you can see the methods and materials are all over the place so I don't think that that would be one of the specs the current manufacturers are that concerned with.  I also don't know what the original spec was,  I suspect it was something high enough out of the typical operating range that there was likely a pretty wide tolerance of exactly when it would pop.

If its reasonable to put in a stock pump I would just do that assuming its a stock ish rebuild for a stock ish application.  Now if the stock pump options are scary but you trust the performance one that does complicate things. If the engine is in the car and its not an external pump then that too is complicated.

If the initial break in is the concern you can probably find a filter without a bypass.  There are only like maybe 6 combinations of threads and gasket diameters that cover 99% of the classic American  engines.  What makes the 100 different models is micron size, drain back valve, and bypass as well as the obvious external diameter and length.

I'm assuming your concern is partially because you are also going to be doing a cam break in?  So fairly quickly you will have to hit and sustain a high for a typical Cad rpm?  You could do things like pre heat the fluids so everything will be above ambient when it starts.  My not be a stock item in AZ but they make a magnetic heater to stick on the oil pan to preheat oil in cold climates.  If the oil is warm before the start the initial pressure won't be as high.  They also make inline heaters that go in like a heater hose that will heat and circulate coolant.  I want to say those things get you into the lower mid 100's for temps. 

I don't think any of this stuff is really a big deal but if you want to do a bunch of little things I don't think they would hurt the engine any.  Time and wallet?  Maybe a little but early engine damage would hurt that too.


     

[Cadman-iac]

  I'm not saying that these filters have a bypass valve, but they do all have a bypass spring in the bottom of the can that will allow the filtering medium to be pushed down or away from the base when it becomes clogged and the pressure is greater than what the spring will hold.
 In that same line of thought, regardless of whether the filtering medium is clogged, if the oil pressure is high enough, (and granted, it would have to be higher if the filter is still able to pass oil through it), the higher pressure will push the medium away from the base allowing oil to bypass the medium, would it not?

 I haven't yet cut apart a 51258 filter to look at the construction of it, but I have cut open several 51060,51061 filters and they do have a coil wound spring in the bottom of the can to act as a bypass in the event that the filter becomes clogged, or overwhelmed as the case may be.
 
 The Wix site information is a bit misleading, in that I know for a fact that the 51061 filters do have a spring inside, but they are saying that it does not have a bypass valve. This is technically true, the spring is not a valve, but it performs the same function.

 So in this case I'm asking, at what pressure does this spring yield to the pressure?

 I have a case of the 51258 filters, so I'll cut one apart and see if it has a spring inside.
 I remember when I worked for the local Napa store in the early 80's that one of the main selling points of their filters, (which were made by Wix at that time), was the use of an actual coil spring instead of just a cheap piece of bent metal to hold the filtering medium against the base as other manufacturers were and are using.
 This spring is one reason why I use Wix filters, and I have a garage full of rebuilt engines for both Cadillac and Chevrolet that I would like to prevent any damage to from a bypass system, be it built into the engine itself or in the filter that's screwed onto it.

 My 472 is currently in pieces again after it sat on an engine stand for over 35 years. I tore it apart again to inspect it and to make sure that when I'm ready to install it in the 56 that it's not going to have a problem.

 But to answer your question, I'm currently working on a Chevrolet 350 that has a high-volume pump in it and I am not sure if I should keep the pump in it or replace it with a stock pump. It has 70 PSI most of the time. It drops a little when it's hot at idle, but I'm worried that that is too much for the filter to handle. By that I mean will it filter 100 percent of the oil pumped to it, or will that spring be overcome by the pressure and allow some oil to push past the filtering medium?
 This is a concern for the Cadillac engine as well. I honestly can't remember what oil pump I bought for it 35 plus years ago, and I'd like to know if the filter will protect it from damage by metal particles from break-in. I never run a filter for more than 2500 miles on a broke in engine, and I change it after 100 miles while I'm breaking in one, so either way the filter should never be clogged and bypass for that reason.
 The only other reason I can think of that a filter should bypass is from excessive oil pressure.
 So what is that pressure? Does anyone know, or know where I can find out?

 I appreciate your response TJ, the link to the Wix site was informative, but I think also misleading, but I guess I didn't explain why or what I wanted to know well enough earlier. Hopefully I've done that this time, (I think).

 Or am I worried about nothing?

 Rick

[Cadman-iac]

  TJ,

 Like I mentioned in my last post, it's been since the early 80's when we cut open various oil filters for a display in the Napa store. The particular filters we used fit a Ford, specifically the 51515, and the competing versions from Fram and someone else's brand.
 I saw on the Wix site that they say that particular filter has a bypass valve in it. I don't remember seeing anything like a bypass valve in there, but it did have the coil spring in the bottom.
 What are they referring to, do you know?

 Rick

[TJ Hopland]

I have not personally cut up that many filters but it seems like I have seen them where there was a valve looking thing at the bottom. 

I'm not saying I know any of this just thinking out loud...  Isn't the spring there just to keep the element jammed up to the main plate?  Oil is getting pumped though the round holes so its on the outside of the element.  It then flows through the element and out the center hole.  I suppose even when new there will be a slight pressure drop going through the element.

Seems to me any restriction from minimal to completely clogged is only going to press the element harder into the plate?  High pressure is on the outside.  Low pressure is the inside.  If the pressure can't get though the element what path will it have to the inside?  Its trying to push the same direction as the spring isn't it?  Without some sort of bypass path/valve how would it be able to move the element away from the plate?  If the flow was the other way, inside to out then ya it would be that simple but that direction doesn't make for as much surface area to collect the crud.

I'm thinking if things are going that bad the most likely scenario is the element will just get crushed and you then get a permanent bypass.  Why do some apparently have an actual bypass valve?  I dunno.  Did Ford have their pressure regulator after the filter or no regulator?  Only oil pumps I have ever taken apart are Buick and Cad where the valves are part of the pump assembly.  Maybe if the pump has a regulator that keeps thing from getting the pressure too high?        

[Cadman-iac]

  God I feel stupid! I don't know why I kept thinking that the oil flow went the other way, from center to outer.
 Maybe because I always prefilled my filters before I installed them and I put the oil in through the center hole.
 What an idiot!! Thanks for the  lesson in the obvious TJ.
 Just disregard my previous questions about bypassing filter elements.
 That makes me feel better now knowing I had looked at it backwards.

 Rick

[TJ Hopland]

Still an interesting discussion.  Why did Ford apparently want a valve in the filter?   Does a small block Chev oil pump have a regulator valve in it?  But a Ford don't?

[Cadman-iac]

Still an interesting discussion.  Why did Ford apparently want a valve in the filter?  Does a small block Chev oil pump have a regulator valve in it?  But a Ford don't?

Yes, Chevrolet oil pumps have a pressure relief valve in the body, but also there's a bypass valve in the oil filter adapter that fits the filter to the block.
I had always been told that the spring in the filter was to let the element move away from the base in the event that the element became clogged.
And for some reason because of this I was thinking the oil flowed from center to outer, otherwise the spring wouldn't work.
So now I'm guessing that the springs only purpose is to keep the element against the base, nothing more.
 The bypass on the adapter will open if the filter clogs.



Rick

[TJ Hopland]

I was going to say oil filter adapter?  But now that you mention it that's right there is that little metal check valve looking thing on those.  That totally explains why the PF25/35's don't need their own internal valve.  Now that you reminded me about those I'm thinking about the 472/500/425/368 pumps and you can see the same sort of thing right next to the nipple on those. There is the nipple, a big rough cast hole (the feed from the pump) and a round port with a valve in it.

So it seems GM decided it was best to put that valve in the filter mount and Ford in the filter itself?  Did GM think it would be more precise?  Or was it a make more money later thing?  Either way they had to install a valve at the time of manufacture but then then Ford gets to sell you several more over time thus making a few bucks more over the life of the car?  Did a new Ford OE filter cost more than a GM one back in the day?  You would think it would have had to cost slightly more.

[Cadman-iac]

  As I've not messed with any Fords other than my old 53 tractor, I couldn't say if their in-filter valve adds any extra cost to the filter.  Probably so, but it's minimal I'd imagine. I do use the 51515 on the tractor, so if I can remember, the next time I change it I'll cut the old one apart and inspect it. You got me wondering about it now.

As for the Chevrolet bypass, it can be removed and the hole plugged to force 100% of your oil to actually go through the filter medium instead of just what the bypass valve allows before opening.

I just took one of my extra oil cooler/ filter adapters to figure out the flow routing.
I've heard about plugging the bypass to get full filtration, so I did it to this one and I'll install it tomorrow.
One concern about doing this is will the filter be able to handle the pressure, but after thinking about it, the filter is already handling the pressure, just not the full flow.
The cooler adapter has 2 bypass valves in it. The first one is for the filter, and the second one is for the cooler in case it can't handle the flow the oil goes through the bypass and directly into the engine.

From the link you provided on the 51061 filters, the burst pressure is 225 PSI, which is far above what this high-volume pump puts out. It's holding up to 70-75 PSI maximum cold, and just slightly less hot.
So I think the filter will be fine, and this will take care of any debris that should be created by the break-in that I was worried about.

Here's a picture of the adapter after I removed the bypass and plugged the hole.
And the 2nd picture you can see the bypass for the cooler.
I believe this is the same system Cadillac used when they were using the small-block Chevy engine in the Brougham and Escalade.






The 3rd picture shows the removed bypass valve laying on the plug.

Rick

[TJ Hopland]

Ya let us know (someone else has to be following this and curious) what you find in that Ferd.  What did that wix spec say 8-10 psi?  But I suppose that isn't total pressure that is just a differential within the filter.  I wonder how dirty (or cold) the oil has to be to hit that sort of differential?  I would assume the bypass in the GM stuff is similar ballpark.  I wonder how often they do bypass?  Like back in the day when you were running 30 weight or 10w-40 was the norm?  I bet in the cold climates they would bypass fairly often. Once we got into 5w and now 0w maybe its rare unless you let em get really dirty?   

All I ever did with those cooler adapters was throw them away so I never looked that close at them to see that thermal valve but it makes sense especially if its an external cooler vs one in the radiator.  I thiink the radiator ones were pretty free flowing but the external ones for sure don't flow well when they are cold.   

I think one time I got a seal kit for one and it seemed like it was leaking again fairly quickly and that was when I found out you could just buy the classic nipple and bolt that up so thats what I did.  If it wasn't leaking at the block the lines would leak or the fittings at the radiator. Maybe they were fine when new but I never owned a new one, by the time I got em they were just a hassle.   

[Cadman-iac]

  Yeah, 8-10 psi was the setting.

 I still think that on the GM filters from Wix, (or anyone else's), that should the medium become clogged the pressure would push the medium down just enough to allow the oil to pass if the bypass was disabled or removed like I just did. The pressure has nowhere else to go but through the filter, be it passing through the medium or around it, it's going to go through the can one way or another. Without a bypass valve in the system, that spring under the medium is basically a pressure relief valve. Something's gotta give, and if it's not that spring, it'll be the can itself, which would make a big mess. Do you know what I mean?

[dadscad]

Just my thoughts on the filter bypass valve function. The pump pressure is pushed to the filter inlet and onto the filter element inlet. The element is rated to flow X gallons of oil per minute. When the filter is new, the differential pressure from the inlet to the outlet may be, let's say a quarter pound difference. Inlet pressure 30 pounds outlet 29_3/4 pounds. As the filter collects debris that X flow becomes less causing the differential pressure from inlet to outlet to change. When the filter clogs enough to restrict the rated gpm flow to create a differential pressure pressure greater than the rated bypass valve, the valve will open enough to relieve the restriction to supply sufficient oilflow to the engine bearings. If the bypass valve is rated at 10 psi and the oil pressure is 30 pounds intering and 19 pounds exiting the filter due to restrictions, the bypass valve opens to compensate the flow to relieve the restrictions. This feature keeps the engine from oil starvation due to oil filter restrictions whether due to debris clogging or to thick of oil.

[TJ Hopland]

To move the whole element away from the plate there would have to be some means for the pressure to act upon it in that direction.  You have the solid plate on the end that the spring is also pushing on helping it to seal tighter.  The rest of the pressure is pushing sideways which probably isn't helping or hurting. 

What happens probably depends on what there is for internal support structure.  Is it a cheap filter that only has the media?  That would probably crush fairly quickly and as it crushes would likely pull away from the plate.  Is it the expanded metal screen?  Seems like I have seen filters where there is essentially another can with holes in it but with the surface area involved that would have to be a pretty thick material to resist say 30 psi.

You would assume once an engine and the oil is hot a filter would have to be pretty dirty to have issues.  I bet most of the time if its going to bypass its going to be cold related.       

[Big Fins]

Which leads to another question of how often do people change their oil and filter?

Because the Cadillac doesn't get driven daily, it's once a year or maybe 1000-1500 miles.

The daily drivers get it changed at 3000 miles. These use full synthetic, have these tiny filters and are both twin turbo engines. These are recommended to be changed at 7500 miles. Even the oil life monitors still give me 50% oil life left. I change it anyway.

Cummins recommended 25,000 miles on my ISX 15 liter diesel engine. I still did it at 10,000 miles and at 600,000 miles, it never used a drop of oil. By then, most ISX's were getting rods, mains and cam followers (lifters) installed because of wear. It also gets a gallon of Lucas Oil Stabilizer at every change. I use that like Franks Hot Sauce, in everything.

The Cadillac can sit for a few months and upon start up, you don't hear a thing out of place in the engine. Not a knock, lifter or rocker tick.

Oil changes are the cheapest insurance you can buy.

[Cadman-iac]

  I change my oil at 2500 miles with conventional oil and 5000 miles on synthetic oil by the odometer, so it's really easy to tell when it's due.


Well instead of installing the modified oil cooler adapter with the blocked bypass, I decided to drop the pan and replace the high-volume oil pump with a stock one.
This will help take a bit of the load off of the distributor and cam gears and I won't have to worry about the filter not catching any debris from the bypass opening because of high oil pressure.
I was also concerned about coolant in the oil from changing the intake manifold. There was a little bit in the oil when I drained it, and I know that some always remains in the pan, so off it came. Glad I did too, more was indeed there.

Thanks to everyone who kicked in on this topic.

TJ, I changed the oil in the tractor about 3 months ago, and as much as it gets used, it'll probably be another year before it needs changed again. Hopefully I'll remember to check the old filter for the bypass valve. I'm curious to know how Ford incorporated it into the filter.

Rick

[TJ Hopland]

Looks like the internal to the filter bypass valve thing is a little more complex than we thought.

https://www.youtube.com/watch?v=1ANmG5PXWMg

If you don't want to watch the video basically what he is pointing out is with bypass valve types of filters there are 2 ways it can be done. The apparently cheap and easy way is to have the valve at the bottom of the element.  Works fine but what he points out is if that valve opens the oil has to flow past the dirty side of the filter possibly flushing crud off in the process which then flows though the valve and into the engine. 

The Motorcraft filter the valve is in a small gap at the top of the element so if the valve opens the oil is basically flowing directly from the inlet holes and through the bypass valve.  I suppose there could be some turbulence that kicks up some trapped crud but it can't be anywhere near as much as yo would get flowing past the dirty element.  I would guess that you get a lot of just sediment sitting in the bottom of the can since there normally isn't really any flow at the bottom.  Only time there would be flow down there is a bottom valve and it opens. 

The GM style were the bypass valve is next to the nipple on the engine side of things I suppose would be even slightly better since the oil doesn't even make it into the filter housing at all if the valve opens.


I wonder when they started screwing around with bypass valves?  I suppose it was likely pretty quickly after they started with the full flow filters. Probably had issues starving the engines or blowing up filters the first winter hopefully in beta testing, not production cars.

Most of the engines that even had filters at first were just bypass filters weren't they?  I remember working on a 28? Chev that had a inline filter plumbed into the side of the engine.  The bypass filters are usually plumbed into the main oil gallery through what is basically the pressure regulator.  Any oil that is 'bleed off' by the regulator is fed into the filter. 

I don't know if the cars did it but many tractors and industrial engines the filter is an upside down canister that is just stuffed full of the media.  There is a hole up through the center of the media that was often filled with a stick for production and shipping that you removed before installation. The base it sat on had a tube that stuck up through that hole and basically squirted the oil up into the media where it then just gravity drained through the media and then through large ports in the base back into the block/pan. 

I know some heavy equipment and some engines like semis have a bypass system in addition to the more typical full flow filters.  The bypass system can be a much finer media because like the early systems you are just tapping off a bit of oil kinda at random that isn't at full pressure or full flow and letting it just kinda trickle through some fairly fine media.  If it plugs up or doesn't catch it all no big deal you are just back to the primary full flow filters to get the big chunks.     

[Cadman-iac]

  I watched the video, it's interesting. I'm wondering why he had an assortment of used oil filters dating back 5 years or more.  Gotta take out the trash sometimes!!

I'm glad GM put the bypass valve outside the filter. I don't like the idea of running the oil over the dirty filter element when the bypass opens.

On why I think the GM filters will bypass internally, is if they plug up with dirt/debris and your actual bypass valve is either blocked or stuck, is that the pressure will push on the top of the element inside the can, and if the oil can't get through the element, I believe it will push the element down just enough to allow the oil to get past the top and out of the center opening into the engine.

That's my theory anyway, I don't know if that happens, and I don't want to test the theory to find out. I didn't install the modified oil cooler adapter, instead, I changed the oil pump. I let my machinist talk me into the high-volume pump, (along with this damned camshaft that is causing all my headaches) when I took the engine to him and told him what I'd like to get out of the engine power-wise.
I won't make that mistake again. I knew his dad for years and they both were big-time drag racers, so I figured he knew what he was doing.
Still trying to fix this mess.

Thanks for all your input TJ, I really appreciate it.
Remind me in about a year that I need to cut open the tractor filter when I change the oil again.

Rick