Valve cover Oil Filter cross reference
- Thread starter duke36
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alexiskai
Well-known member
You do want a bypass valve. You also want a silicone anti-drainback valve.
I am not sure what the ideal number is for when the bypass valve should open. My intuition is that you want it to open fairly high, like 22-30 psi. That would allow the engine to get oil on a cold start. The stock pump can generate something like 100 psi if you block the outlet, so it would have no trouble opening a bypass valve at 30. And then the valve would close as the oil warmed up, forcing the oil through the filter media.
If the bypass opens too soon (e.g., the NAPA Gold 1515 valve opens at an 8 psi differential), theoretically it could remain partially open all the time, because the pressure on the back side of the filter would be close to zero (since it dumps into the valve chamber).
I could be wrong, though. It might depend on the filter media – synthetic media with a low flow rate would create a higher pressure differential than paper media (and also filter better). Really hard to know without quantitative testing.
I am not sure what the ideal number is for when the bypass valve should open. My intuition is that you want it to open fairly high, like 22-30 psi. That would allow the engine to get oil on a cold start. The stock pump can generate something like 100 psi if you block the outlet, so it would have no trouble opening a bypass valve at 30. And then the valve would close as the oil warmed up, forcing the oil through the filter media.
If the bypass opens too soon (e.g., the NAPA Gold 1515 valve opens at an 8 psi differential), theoretically it could remain partially open all the time, because the pressure on the back side of the filter would be close to zero (since it dumps into the valve chamber).
I could be wrong, though. It might depend on the filter media – synthetic media with a low flow rate would create a higher pressure differential than paper media (and also filter better). Really hard to know without quantitative testing.
After reading more threads, some people express concerns that the valve cover design filter pipe may potentially restrict flow to the front of the engine on start up due to placement in the oil passage .Perhaps a filter with less filter capacity is better than one with high filtration rates, especially if the oil and filter are changed frequently ?
The Fram PH8A and the Motorcraft FL1A seem to be similar in design.
Another thought is that if a right angle adapter is employed on the side cover, could that improve oil flow because the filter would be full of oil at all times when the oil pump
starts up ?
The Fram PH8A and the Motorcraft FL1A seem to be similar in design.
Another thought is that if a right angle adapter is employed on the side cover, could that improve oil flow because the filter would be full of oil at all times when the oil pump
starts up ?
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alexiskai
Well-known member
That's why the bypass valve design is important, you want that valve to pop open on a cold start and shunt oil directly to the valve chamber.
High capacity is fine, and in fact usually high capacity and higher flow rate go together, other things being equal, because there's more media surface area, which allows more oil to cross under lower pressure. I agree that for a full-flow filter you do not want something like the PL30001, which has very low-micron filtration.
The anti-drainback valve should keep the filter full between starts, and on a cold start the orientation won't matter because the bypass valve will open. The right-angle adapter will make changing the filter less messy, but there's no evidence that it improves performance.
Thanks for post 5 . I forgot to post your 9-22 post with interesting info. about the filter placed vertically. If I understand correctly because oil is in the vertical filter, no need to punch holes in the membrane ? The Kenz design pumps oil out of the side block plug while the valve cover design pumps through the front valve cover passage . Still not sure if one system is better than the other.
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alexiskai
Well-known member
Put simply, with a full-flow filter that is changed regularly, there is no need to punch holes in the anti-drainback membrane, regardless of the filter's orientation. The stated purpose of punching the holes, among those who advocate it, is so that the Model A's purportedly anemic oil pump can overcome the resistance of the membrane and get oil into the filter.
I believe this practice originated in the '60s or '70s, a time at which two things were true:
- The full-flow valve cover kit had not yet been invented
- Filters used mostly nitrile ADB membranes
However, a full-flow filter with a hardened membrane would simply block the entire oil volume from the pump – and as I said earlier, the Model A's positive-displacement pump is perfectly capable of putting out very high pressure if the circuit is blocked. Any functional stock pump can push through any ADB membrane, brittle or not. So there is no need to disable the membrane by perforating it. Having said that, purchasing a filter with a silicone anti-drainback membrane is good insurance at a low price.
Werner
Well-known member
I also have concerns about how the bypass valve is supposed to work (remark to #2), since there is no back pressure behind the filter.
It's different with modern pressure lubrication, where the crankshaft bearings have 5 bar (for example) and this pressure is the back pressure behind the bypass valve.
I think that a bypass valve is bad if there is no oil pressure on filters backside and the oil doesn't flow through the filter medium?
I hope, my language is understandable.
It's different with modern pressure lubrication, where the crankshaft bearings have 5 bar (for example) and this pressure is the back pressure behind the bypass valve.
I think that a bypass valve is bad if there is no oil pressure on filters backside and the oil doesn't flow through the filter medium?
I hope, my language is understandable.
alexiskai
Well-known member
Bypass valves on modern oil filters open at between 4 psid (pressure differential) and 75 psid, depending on the filter. Because Model A filters exit directly into an open chamber, the pressure differential will depend greatly on the resistance exerted by the filter media. To take an extreme example, if the filter media were a metal mesh like you might strain tea with, it would create almost no flow resistance, and thus the bypass valve would almost never open, because the pressure differential would be almost nil. On the other end of the spectrum, synthetic media designed to filter down to the micron level will be hard for oil to pass through, creating a pressure differential that theoretically might cause the bypass valve to open.
How much differential? 4 psi? 8? 20? I have no idea. 20 seems too high, though, for operating temp oil.
Some oil will always pass through the filter media by capillary action, so the concern is not that a filter with a weak bypass valve won't function at all; rather it would function as a bypass filter (apologies for the double meaning of bypass), filtering a small percentage of the total flow.
To address Werner's question more directly, a bypass valve is important to have on a full-flow filter because it facilitates oil flow during a cold start. But at some point you want it to close, and that's the question we need more data for.
Y-Blockhead
Well-known member
I think you are looking at the bypass valve incorrectly. It is a safety device to open when the filter becomes clogged, not when there is a differential pressure between the inlet and outlet. It does not matter that it is discharging into the valve chamber with little to no pressure..
When the filter media become clogged, the inlet pressure build until the pressure overcomes the spring pressure (not differential pressure) in the bypass valve, thus bypassing the filter and providing oil to the engine.
It will not open at startup.
I run a WIX 51515 and the bypass opens at 8-11 psig.
When the filter media become clogged, the inlet pressure build until the pressure overcomes the spring pressure (not differential pressure) in the bypass valve, thus bypassing the filter and providing oil to the engine.
It will not open at startup.
I run a WIX 51515 and the bypass opens at 8-11 psig.
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alexiskai
Well-known member
Bypass valves are generally thought to open briefly on cold starts, but it's certainly possible that it wouldn't happen if the oil is able to get through the media.
https://www.noln.net/articles/1564-bypassing-the-oil-filter
katy
Well-known member
Put both on, then you have the best of both technologies.
I once worked on some Cummins engines that had both types of oil filters.
The Master Cylinder
Well-known member
Why would a bypass filter remove the soot better than a full flow filter if you are using the same filter in both?
alexiskai
Well-known member
It wouldn't, but that's not how diesel remote bypasses work. The Model A bypass system, using spin-on filters designed for full-flow applications, is actually kinda weird in the bypass filter world.
Diesel bypass systems use specialized bypass filters that filter down to 1 micron and are very large, like coffee-can size – which you can do because you're typically fitting them in a truck engine bay with plenty of room. It's also common to see toilet paper used for the filter media.
alexiskai
Well-known member
The only reason I know a lot about remote bypass filters is that I got interested in them about 20 years ago and ended up fitting one to an '03 Corolla. I knew nothing about machinist technique, so I did a terrible job drilling and tapping the return into the head. Eventually, metal shavings got into the crankcase and it threw a rod about 50,000 miles later. But the oil was very clean.