Pressure at which oil filter by-pass comes on?
04-18-2004, 02:35 PM
#1
New Member
Thread Starter
Pressure at which oil filter by-pass comes on?
I have just started using Mobil 1 5/30, I have noticed that oil pressure during warmup can be pushed to 120, peg oil meter, with just a tap of gas pedal (1500/2k or so RPM). Question is at what pressure does the by-pass kickin for Nissan filters?
I search every where but no info on this.
Second question of whether the by-pass shuts off once oil pressure drops. I have noticed that some filters have a little springs at the bottom (or top) of the oil filter. Will this spring shut-off by-pass?
This pegging of oil pressure (120) only happens during first minute or two while engine warms up. Once warmed up oil pressure states middle half (30 to 90) from idle to 4500. Hardly ever go past 4500 RPMs.
Hate to pop open by-pass on oil filter and then not filter any oil, yes I have changed filter just to be on save side. Oil is still translucent honey colored.
Any ideas ?
I search every where but no info on this.
Second question of whether the by-pass shuts off once oil pressure drops. I have noticed that some filters have a little springs at the bottom (or top) of the oil filter. Will this spring shut-off by-pass?
This pegging of oil pressure (120) only happens during first minute or two while engine warms up. Once warmed up oil pressure states middle half (30 to 90) from idle to 4500. Hardly ever go past 4500 RPMs.
Hate to pop open by-pass on oil filter and then not filter any oil, yes I have changed filter just to be on save side. Oil is still translucent honey colored.
Any ideas ?
04-22-2004, 09:53 AM
#3
New Member
Thread Starter
It may not be called filter bypass but it's a valve that is supposed to pop open when filter clogs and allows oil to flow. Guess it is better to have dirty oil than no oil circulating.
Nissan OEM filter not only have this "bypass" but also a flowback restriction to keep oil from draining back to oil pan when engine is off. Hence the dirty oil is kept in the filter and oil pressure rises faster when engine is turned on. When either of these features is not working some dirty oil gets mixed in with the other four quarts that have been filtered.
Other filters may also have these features but you have to check for them. The by-pass valve is standard on all filter and now the flow back valve is getting to be more standard. The flow back is usually a piece of rubber seen thru the holes around the main attached point/hole.
Think of this, if the by-pass valve is popped open at 100-PSI and does not shut-off at lower PSI then the oil is not being filtered once the valve is popped open. What if this happens the first couple of hundred miles after an oil change, your oil is not being filtered.
This is why I keep an eye on the oil pressure not being too low or too high. Since the Z meets has 0, 60 and 120 marking too low for me is below mid point between 0 and 60 at idle. Thicken oil generally can be spotted with idle oil pressure close to 60. Too high would be at the point the by-pass valve pops....hopefully between 100 and 120.
With 5/30 Mobil 1 is not hard to reach close to 90 (between 60 and 120) when reving the engine over 3/4k rpms.
Again I do have any information on the by-pass valve pressure or whether is closes once popped open.
Nissan OEM filter not only have this "bypass" but also a flowback restriction to keep oil from draining back to oil pan when engine is off. Hence the dirty oil is kept in the filter and oil pressure rises faster when engine is turned on. When either of these features is not working some dirty oil gets mixed in with the other four quarts that have been filtered.
Other filters may also have these features but you have to check for them. The by-pass valve is standard on all filter and now the flow back valve is getting to be more standard. The flow back is usually a piece of rubber seen thru the holes around the main attached point/hole.
Think of this, if the by-pass valve is popped open at 100-PSI and does not shut-off at lower PSI then the oil is not being filtered once the valve is popped open. What if this happens the first couple of hundred miles after an oil change, your oil is not being filtered.
This is why I keep an eye on the oil pressure not being too low or too high. Since the Z meets has 0, 60 and 120 marking too low for me is below mid point between 0 and 60 at idle. Thicken oil generally can be spotted with idle oil pressure close to 60. Too high would be at the point the by-pass valve pops....hopefully between 100 and 120.
With 5/30 Mobil 1 is not hard to reach close to 90 (between 60 and 120) when reving the engine over 3/4k rpms.
Again I do have any information on the by-pass valve pressure or whether is closes once popped open.
04-27-2004, 09:17 PM
#4
You're thinking is right, but the filter nor the oil is the issue. The oil pump used in the VQ35 is the same oil pump used in the the JDM only SR20VE and 16VE. A lot of SR guys import this pump for their motors when they go turbo. They also idle at 90+ psi when cold. You just have to wait for the oil to heat up before driving hard. As far as oil pressure to open the by-pass, that depends on the filter. A bunch of guys over at www.bobistheoilguy.com are compiling a list right now and doing a pretty cool experiment with several different filters that, among other things, looks at various by-pass pressures. Just click the link and head to the forums to read up, its a great site.
05-10-2004, 11:30 AM
#5
New Member
Thread Starter
Got following reply from WIXFILTERS.com - Oil Filters
Oil filter bypass valves are differential pressure valves. They open and close based on the difference between the oil pressure coming into the filter and the oil pressure coming out of the filter. This is differential oil pressure not system working pressure. The filter for your application has a bypass valve set at 8-11 psid. This means it will start opening at 8 psid and be full open at 11 psid. For example, if you have 50 psi oil pressure coming into the filter and it drops to 39 psi coming out, the filter bypass valve will be fully open. It will close when the differential oil pressure drops below 8 psid. For example, if you have 50 psi coming in and only 45 psi coming out, the bypass valve will not be
open.
Thank you for your inquiry.
C. G.
Senior Technical Service Manager
==========
So this is may be good reason to change the filter earlier than changing Mobil 1 or similar oils.
In this filter's case a drop of 16% at 50 psi would start opening the filter by-pass valve with differential pressure of 8 psi(d). At 90 psi - the 8 psid (d is for differential as used by WIX) would be a ~10% drop. At 120 psi the 8 psid is about 7% drop.
Since the oil pump produces higher pressures then need to look at the lower percentage drops across filter.
For me using 5/30 Mobil 1 "normal driving around" the oil pressure hangs mainly ~90psi hence looking at having by-pass valve opening with a drop of 10%.
Oil filter bypass valves are differential pressure valves. They open and close based on the difference between the oil pressure coming into the filter and the oil pressure coming out of the filter. This is differential oil pressure not system working pressure. The filter for your application has a bypass valve set at 8-11 psid. This means it will start opening at 8 psid and be full open at 11 psid. For example, if you have 50 psi oil pressure coming into the filter and it drops to 39 psi coming out, the filter bypass valve will be fully open. It will close when the differential oil pressure drops below 8 psid. For example, if you have 50 psi coming in and only 45 psi coming out, the bypass valve will not be
open.
Thank you for your inquiry.
C. G.
Senior Technical Service Manager
==========
So this is may be good reason to change the filter earlier than changing Mobil 1 or similar oils.
In this filter's case a drop of 16% at 50 psi would start opening the filter by-pass valve with differential pressure of 8 psi(d). At 90 psi - the 8 psid (d is for differential as used by WIX) would be a ~10% drop. At 120 psi the 8 psid is about 7% drop.
Since the oil pump produces higher pressures then need to look at the lower percentage drops across filter.
For me using 5/30 Mobil 1 "normal driving around" the oil pressure hangs mainly ~90psi hence looking at having by-pass valve opening with a drop of 10%.
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