Mine is definitely the 2nd gen
2019 Pentastar 3.6L V6 Anti Drain Back Capability
- Thread starter Bellavita
- Start date
Then why does the system drain back oil, and then the Baxter unit was invented to prevent that oil drain back?
Hi ZeeOSix,
I hope you can help me with your first question because I've not been able to find a report that says they empty out and if they do how much. I've gone through pages of threads on this topic but can't find a technical document stating how much these systems empty.
I've watched the Baxter video and Kevin at Baxter claims the 3.6 Pentastar empties in 30 minutes. But what does empty mean?
I started my 2019 Grand Cherokee for the first time in four days and it starts immediately with no oil pressure light, no ticks.
And the most important question, "is damage done at startup?" in the Toyota, Subaru, Pentastar and Ford engines Baxter is making this device for. I would welcome comments from an automotive engineer on the designed performance of the lubrication systems of these engines.
On your second question why did Baxter invent it. I found most of the reviewers on the Baxter sight comment that the complexity of changing a cartridge filter is eliminated with the switch to a spin on filter the Baxter provides, definitely a good thing for consumer convenience. Second, if the Baxter unit can keep more oil in the system people will perceive that as good thing and feel it will extend the life of their engine.
I hope you can help me with your first question because I've not been able to find a report that says they empty out and if they do how much. I've gone through pages of threads on this topic but can't find a technical document stating how much these systems empty.
I've watched the Baxter video and Kevin at Baxter claims the 3.6 Pentastar empties in 30 minutes. But what does empty mean?
I started my 2019 Grand Cherokee for the first time in four days and it starts immediately with no oil pressure light, no ticks.
And the most important question, "is damage done at startup?" in the Toyota, Subaru, Pentastar and Ford engines Baxter is making this device for. I would welcome comments from an automotive engineer on the designed performance of the lubrication systems of these engines.
On your second question why did Baxter invent it. I found most of the reviewers on the Baxter sight comment that the complexity of changing a cartridge filter is eliminated with the switch to a spin on filter the Baxter provides, definitely a good thing for consumer convenience. Second, if the Baxter unit can keep more oil in the system people will perceive that as good thing and feel it will extend the life of their engine.
I don't think Baxter would invent this product if there wasn't really a need for it. Maybe a main factor in the oil drain down is the built-in ADBV in the bottom of the cartridge filter cavity? Maybe some work better than others, or some degrade and don't work as well.
Have you ever experimented with your vehicle? When you change your oil filter, how much oil is left in the filter cavity? Have you changed the filter hours after the engine was shut down vs in less than 30 minutes after a shutdown? Do some experimentation on your vehicle and find out first hand is all I can suggest. Otherwise, I'd have to believe Baxter has investigated the issue and came up with the product the did.
This is similar along the lines of "does installing an oil filter dry vs pre-filling it" make a difference in engine wear. I'm sure you've seen the couple of latest threads on that subject. Will it make a difference in engine wear over the long run? ... maybe it could IMO, especially when it may be happening with every start-up. With a dry filter change every 5-10K miles, not so much due to the much lower "dry" start counts. I'll say starting an engine with an empty filter and gallerias vs not empty isn't ideal. That the main reason ADBVs where invented in oil filters or cartridge filter cavities.
I'd say the guy who started that thread you linked to on the Challenger forum is claiming something without any real proof, and based just on the fact that he sees a built-in ADBV in the housing and believes the ADBV is working perfectly. Is it really?
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Thank you ZeeOSix for your reply, I always appreciate your insights. I’ll definitely try your test recommendations but unfortunately it won’t be for awhile because I have only 1,028 miles on my latest Valvoline Advanced Synthetic oil change! But I have been doing research and have conducted a test to share.
Pentastar Engine Lubrication Map
I found a complete lubrication map showing the path of oil through the entire Pentastar engine. There are an incredible number of passages for small orifice piston and camshaft spray nozzles, the complex VVT system in the camshafts and main galleries. It’s well worth the time going through it in its entirety.
Observations:
1. The oil filter & cooler housing sits up in the V well above the variable speed oil pump.
2. The main large oil gallery within the V is positioned below the oil filter and cooler assembly.
3. The oil pressure sensor switch is attached directly behind the oil cooler.
4. The nose of the cartridge with the green o-ring depresses a valve to keep oil within the cartridge housing. When the cap is unscrewed to change the cartridge, it comes out automatically with the cap opening the valve to drain the housing. Based on the oil path depicted some amount of oil is being held in the canister.
Filter Drain Observations From Two BITOG Members from July, 2021.
I found a couple of BITOG members comments confirming oil is held in the system and drains out when the cartridge is pulled during an oil change.
https://bobistheoilguy.com/forums/threads/convert-your-pentastar-to-a-spin-on-filter.343734/
Time To Pressure Test
The question remained “is oil being held in the system or is it draining back over time?"
I did a test I call “Time To Pressure”. With a stopwatch in hand, I started my Jeep Grand Cherokee and timed how long it took to register pressure on the gauge for three conditions:
- Sitting overnight
- Sitting 2.5 hours after being run
- A Restart, i.e. shutting off the engine and then starting it immediately
With no significant variation in the time to pressure and the fact that the filter housing does hold oil because it drains during an oil change, the data is telling me that there is some amount of oil that is not draining back during normal operation of the vehicle.
I’d appreciate your comments on my analysis, test design and conclusion.
The Baxter Performance Filter
I'm intrigued by this product and would like to measure the improvement the Baxter unit provides. I would appreciate it if those of you that have purchased the Baxter device could conduct the "Time To Pressure" test and provide your results in this thread. I’ll put them in a table and post the results.
- Share your vehicle engine (examples: Pentastar 3.6 V6, Subaru FB25)
- The condition when you started the engine - Overnight, Restart or Time in Hours
- Time result in seconds
Thank you!
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Are all these forum posts yours or are you randomly copying other peoples info/posts without crediting them?
Hi Rand,
Thank you for the feedback, I appreciate it greatly. I could have done a much better job in recognizing and crediting the people from the postings.
The first post is from John from the ChallengerForum site.
Thank you John for your insights on the drain design within the canister and guidance on removal.
The lubrication map is by Alex Koon of Prezi.com.
Thank you Alex, an amazing piece of work in building this comprehensive map.
The second post is from two BITOG members, 4WD and oldHp.
Thank you 4WD and oldHp for your experiences in the draining of the cartridge canister.
John, Alex, 4WD and oldHp, my apologies for not crediting you in my initial posting.
Rand,
Again my thanks for bringing this to my attention, I'm grateful.
Thank you for the feedback, I appreciate it greatly. I could have done a much better job in recognizing and crediting the people from the postings.
The first post is from John from the ChallengerForum site.
Thank you John for your insights on the drain design within the canister and guidance on removal.
The lubrication map is by Alex Koon of Prezi.com.
Thank you Alex, an amazing piece of work in building this comprehensive map.
The second post is from two BITOG members, 4WD and oldHp.
Thank you 4WD and oldHp for your experiences in the draining of the cartridge canister.
John, Alex, 4WD and oldHp, my apologies for not crediting you in my initial posting.
Rand,
Again my thanks for bringing this to my attention, I'm grateful.
Based on the time to pressure testing, it seems to be showing not much if any oil drain down when the engine is shut off. Next time you do an oil and filter change, or better yet if you just changed the oil filter, see how long it takes to make the same pressure target in your test. That would give you a better baseline of how long a system without being completely filled with oil might take to built oil pressure. Do you have an actual pressure gauge, or are you going by an oil pressure light? I'm wondering how well some PD pumps can pump, even with some air in the system when the engine is running, and if they can build enough pressure even with some air in the system to make an oil warning light go off if the trip point on the oil warning light is set pretty low. Any idea what oil pressure (from the oil pressure switch near the oil cooler) makes the light go off?Time To Pressure Test
The question remained “is oil being held in the system or is it draining back over time?"
I did a test I call “Time To Pressure”. With a stopwatch in hand, I started my Jeep Grand Cherokee and timed how long it took to register pressure on the gauge for three conditions:
- Sitting overnight
- Sitting 2.5 hours after being run
- A Restart, i.e. shutting off the engine and then starting it immediately
With no significant variation in the time to pressure and the fact that the filter housing does hold oil because it drains during an oil change, the data is telling me that there is some amount of oil that is not draining back during normal operation of the vehicle.
I’d appreciate your comments on my analysis, test design and conclusion.
It seems the system is designed to drain some oil out of the canister housing (not counting what's supposed to be left in the housing until the cartridge filter is pulled out to drain the housing), otherwise there would be a huge oil mess any time the filter cap was remove. In other words, the whole filter element housing can't be 100% full of oil after engine shutdown, otherwise when the cap is removed oil would puke - but does it? ... doesn't sound like it does. So where does that oil go? If you remove the filter housing cap, and look into the housing with the filter element still installed, is the housing still mainly full of oil? If you take a flashlight and look, how deep is the oil in the housing before the element is removed, which then allows any oil in the housing to drain out the bottom of the housing? Have you ever tired removing the filter housing cap a minute after engine shutdown to see if oil pukes out the cap when removed, meaning the housing would be completely full of oil. You could do that after running the engine cold so the oil puked out wouldn't be too hot. Maybe there is always an air pocket inside the top of the housing (?) - I wouldn't think so after the engine was ran through some higher RPM, but who knows for sure without testing.
Like I mentioned before, maybe not all Pentastar engines exhibit the oil drain down like Baxter is claiming. Is the Baxter unit for only specific Pentastar engine models/years? Maybe the brand of oil filter has a factor in this if the built-in seal on the bottom of the filter isn't working correctly in the housing, and leaks some causing the filter housing to empty when the engine is off. I don't own one and only look into this somewhat from the curiosity factor, and I like to look for root causes when issues arise.
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Hi ZeeOSix,
The gauge I use is on the dashboard of my Grand Cherokee. When I start the engine, I start the watch and car and as soon as the gauge leaves zero, I stop and mark the time. I'm doing the same thing with my Subaru Forester except I time when the oil pressure light goes off because it does not have an oil pressure gauge.
When assembling the cartridge the nose with the o-ring depresses a valve in bottom of the filter housing sealing off the compartment. When removing it, the valve is opened when changing the oil and the compartment drains. A very simple robust design.
There is much discussion on this forum and the Baxter Performance site about anti drain back and I'm working to get to the facts on how it performs for daily vehicle operation.
What I've learned so far is the Pentastar engine in my Grand Cherokee, gets to pressure in the same time, 1.6 seconds regardless of its engine off time. I'm also collecting the time to pressure values for my Subaru Forester.
Baxter has a unit for all Pentastar engines since the engine's inception (over 10 million have been built), Subarus, Ford Eco Boost engines and Toyotas that use a cartridge filter. Please see their website for the applications.
With a baseline of 1.6 seconds "time to pressure", we can now compare that to a Pentastar engine with a Baxter units time to pressure. This is why I'm hoping a BITOG member with either a Pentastar or Subaru engine with a Baxter will do this time to pressure test.
The gauge I use is on the dashboard of my Grand Cherokee. When I start the engine, I start the watch and car and as soon as the gauge leaves zero, I stop and mark the time. I'm doing the same thing with my Subaru Forester except I time when the oil pressure light goes off because it does not have an oil pressure gauge.
When assembling the cartridge the nose with the o-ring depresses a valve in bottom of the filter housing sealing off the compartment. When removing it, the valve is opened when changing the oil and the compartment drains. A very simple robust design.
There is much discussion on this forum and the Baxter Performance site about anti drain back and I'm working to get to the facts on how it performs for daily vehicle operation.
What I've learned so far is the Pentastar engine in my Grand Cherokee, gets to pressure in the same time, 1.6 seconds regardless of its engine off time. I'm also collecting the time to pressure values for my Subaru Forester.
Baxter has a unit for all Pentastar engines since the engine's inception (over 10 million have been built), Subarus, Ford Eco Boost engines and Toyotas that use a cartridge filter. Please see their website for the applications.
With a baseline of 1.6 seconds "time to pressure", we can now compare that to a Pentastar engine with a Baxter units time to pressure. This is why I'm hoping a BITOG member with either a Pentastar or Subaru engine with a Baxter will do this time to pressure test.
Is it robust and working 100%? Only way to know is to verify somehow, like I mentioned in post 28. How do you know it's not slowly leaking out and draining the filter housing to some degree without visual verification? If you removed the filter housing cap 24 hours after a shutdown, how much oil is still actually in the filter housing before the cartridge is removed? Is the level of the oil inside the housing high and close to the top of the housing, or is it very low near the bottom of the housing before the filter is removed? Does any oil leak out from the top of the housing when the cap is removed, or does that never happen? If it never happens, why does the oil level go down inside the housing below the top of the housing from just sitting?
That is the correct method, not torque it to 100 lb/ft like the guy did on mine.
Good Morning ZeeOSix,
I found a video on the Baxter site confirming your hypothesis in thread #28 that the canister housing drains down. The video is a side by side of the two oil filter systems; Pentastar design on the left and the Baxter unit on the right. You’ll find it at the Baxter Performance site under Videos and is titled “Pentastar Drainback”. I hope you can watch it, I would greatly value your insights on it.
The video begins with an engine start that fills the housings and then engine off. Time lapse photography shows the canister housing drains in 35 minutes and the oil in the Baxter unit not moving after 48 hours. When I've done an oil change, about 15 minutes has elapsed from engine off to when I remove the filter. The oil is low in the housing that point.
There are two places the oil can drain in the Pentastar design:
1. The vertical feeder passage from the pump to the filter housing above and/or
2. The horizontal exit from the housing to the oil cooler that feeds the main gallery below.
The housing drain is closed with the cartridge in place and oil cannot drain from there.
With the filter housing drained in 35 minutes per the video, how can my time to pressure be the same with a full housing after a restart and with an empty housing after sitting 2.5 hours and 24 hours?
Have the lubrication galleries been designed to hold enough oil in between engine starts, regardless of time, to protect the engine? A form of anti drain back?
Is the pump so powerful that anti drain back is not needed?
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I agree based on what I see too. There apparently is no anti-drainback valve (ie, a check valve) of any kind between the oil pump and the oil filter housing. The only thing that holds back the oil in the gallery (and filter housing) between housing and pump is the oil pump itself. Maybe some oil pumps are tighter than others, so this drainback phenomenon may vary between engines. With not ADBV/check valve, between the pump and filter housing, the oil can drain back over time (green arrows) due to gravity. The "plug" the oil filter provides at the bottom of the filter housing is to only yo drain out the small residual oil volume left in the housing (below the blue line in my annotated figure) when the filter is changed.
Sidenote: The guy on the Challenger site who started that thread that you link to earlier (ref post 10) was wrong when he said:
"There is a anti drainback valve. The engineers that designed and built the engine aren't stupid. here is how it works, look at the following picture from engineering illustrations."
He seems to be confusing the plug below the filter to drain the residual oil in the housing with a "anti drainback valve". I see no evidence of a true anti-drainback valve between the pump and filter housing in this oiling system.
Like mentioned earlier, it's possible that the sensor for the oil pressure warning light triggers the warning light off at a very low pressure, and if there was some air in the system it's possible that the sensor would still make the warning light to off pretty quickly. For instance, If some air is trapped in the middle of an oil column, ie: there was just an air pocket in the filter housing because it drained down some, the air will compress quickly from the incoming oil and still transmit pressure through the gallery to the pressure sensor by the oil cooler. On the other hand, If a gallery was completely empty, and air was allowed to escape on the outlet of the gallery to atmospheric pressure, then it would take a lot longer for pressure to build and the warning light to go out.
IMO, if you are not seeing any real difference in your "time to make the oil pressure light go out" tests, then I wouldn't worry about it. But if you saw a big difference (like it takes 3 or 4 times longer), then it might be worth doing something about it. Maybe the oil pump in your engine is pretty tight, and doesn't drain the housing down much with extended sit time. Only way to know is to remove the filter housing cap and do a visual "oil level vs sit time" test at different time intervals to see if yours is draining all the way down with extended time.
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Good Evening ZeeOSix,
A clarification. I'm using the oil pressure gauge on the dashboard to time when the pressure exceeds zero, not a warning light.
Would air in the system influence a gauge in the same way? What I observe is the pressure will hit 5 then rapidly spike to 31 and then to 80 all in 1.4 seconds. This is on a cold start where the engine has sat overnight.
Thank you for all your detailed feedback and thoughts throughout this thread.
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Is you oil pressure gauge a factory gauge, or one that you put in yourself? Where does it pickup the oil pressure at on the engine ... the same location near the oil cooler that is shown in the previous figures? Is it actuated by an electrical signal, or is it the old fashioned type pressure gauge, like I explain below?
It may be possible that even with some air pockets in the system the pressure gauge could act the way you see it acting. Any air between two "slugs" of oil will just compress to whatever pressure it needs in order to move the oil in front of it through the system. It might take a hair longer to react, but it may not be that noticeable. As an example, I had an old pickup many years ago that I installed one of those mechanical oil pressure gauges under the dash, and it used that small clear nylon tube that ran from the back of the pressure gauge to a fitting on the engine to sense oil pressure directly. That tube was not filled 100% with oil, but I could see air pockets throughout the tube's length between the engine and the mechanical gauge. That gauge worked just as good with some air pockets in the tube that it would have being filled 100% with oil. It may not have went from zero to full pressure quite as fast, but it was still really fast reacting.
A test you could do is this. Let the Jeep sit 24 hours before each test 1) and 2) described below to have constancy. Do a cold start and accurately measure the time to hit the cold start idle max oil pressure.
1) Minimum filter housing air pocket test. Remove filter housing cap. If the oil level is down from the top of the housing, carefully add enough new oil to bring the level to the top so that the air pocket in the housing is minimized. Install the filter housing cap and then immediately do a cold start-up to max pressure time measurement as accurately as possible.
2) Maximum filter housing air pocket test. Do the same test as 1) above, but this time remove the oil filter cartridge to drain the filter housing as much as possible, thereby giving the maximum air pocket in the filter housing. Reinstall the filter and housing cap, then do the cold start-up to max pressure time measurement again.
Compare the two tests and see if you can see a distinguishable difference in time to max oil pressure. If you can't really see a big difference in time than that would prove that an air pocket in the filter housing can not really be seen by the reaction of the pressure gauge.
Glad to help out anytime ...
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Good Morning ZeeOSix,Is you oil pressure gauge a factory gauge, or one that you put in yourself? Where does it pickup the oil pressure at on the engine ... the same location near the oil cooler that is shown in the previous figures? Is it actuated by an electrical signal, or is it the old fashioned type pressure gauge, like I explain below?
It may be possible that even with some air pockets in the system the pressure gauge could act the way you see it acting. Any air between two "slugs" of oil will just compress to whatever pressure it needs in order to move the oil in front of it through the system. It might take a hair longer to react, but it may not be that noticeable. As an example, I had an old pickup many years ago that I installed one of those mechanical oil pressure gauges under the dash, and it used that small clear nylon tube that ran from the back of the pressure gauge to a fitting on the engine to sense oil pressure directly. That tube was not filled 100% with oil, but I could see air pockets throughout the tube's length between the engine and the mechanical gauge. That gauge worked just as good with some air pockets in the tube that it would have being filled 100% with oil. It may not have went from zero to full pressure quite as fast, but it was still really fast reacting.
A test you could do is this. Let the Jeep sit 24 hours before each test 1) and 2) described below to have constancy. Do a cold start and accurately measure the time to hit the cold start idle max oil pressure.
1) Minimum filter housing air pocket test. Remove filter housing cap. If the oil level is down from the top of the housing, carefully add enough new oil to bring the level to the top so that the air pocket in the housing is minimized. Install the filter housing cap and then immediately do a cold start-up to max pressure time measurement as accurately as possible.
2) Maximum filter housing air pocket test. Do the same test as 1) above, but this time remove the oil filter cartridge to drain the filter housing as much as possible, thereby giving the maximum air pocket in the filter housing. Reinstall the filter and housing cap, then do the cold start-up to max pressure time measurement again.
Compare the two tests and see if you can see a distinguishable difference in time to max oil pressure. If you can't really see a big difference in time than that would prove that an air pocket in the filter housing can not really be seen by the reaction of the pressure gauge.
Glad to help out anytime ...
I have a restored 1986 Jeep CJ7 with a mechanical gauge and nylon tube and it behaves exactly as you described including the air pockets in the tube.
The oil pressure gauge is from the factory, it is electric and is attached to the oil cooler.
The overall testing you described makes sense except the #1 Minimum test will not be possible because the cap cannot removed alone, the filter is attached it. This is so the drain for the housing at the bottom of the filter gets opened automatically when the cap with filter is unscrewed. The Pentastar engineers did a good job insuring the housing would get drained during an oil change!
Got ya. So you could at least do the following, which will give you the extreme case.The overall testing you described makes sense except the #1 Minimum test will not be possible because the cap cannot removed alone, the filter is attached it. This is so the drain for the housing at the bottom of the filter gets opened automatically when the cap with filter is unscrewed. The Pentastar engineers did a good job insuring the housing would get drained during an oil change!
Let the engine sit 24 hours. Start the engine and get time to full pressure. Let it run for only for ~30 seconds to ensure the whole oiling system is full of oil without heating the oil (ie, try to keep the viscosity from changing with heat). Shut down the engine and immediately remove the filter to completely drain the entire filter housing. Reinstall the filter and then do another start-up and see if the time to full pressure is different. If it's not much different at all, then that tells you that using the time to full pressure test is not very sensitive to the system having a big cavity full of air in it at start-up.
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Good Morning ZeeOSix,
I came up with another test. I timed how long it takes to fill the Pentastar cartridge housing watching the Baxter Performance video. The housing is completely empty at the video start because one can see the cross at the bottom of the cartridge.
I started my watch at the first sound of the engine cranking to the time the lens is completely blanked out. The table below compares the results of timing the vehicle pressure gauge to greater than zero to the Baxter Video oil housing fill time. The average is .3 seconds longer on the timing the video fill.
One of the possible causes of the difference is starting the watch to the first sound of the engine cranking in the video. It is difficult. Timing the gauge is easier to synchronize because one hand hits the engine start and the other hits the stop watch button.
The 2.5 hour and Overnight with an empty housing were 1.4-1.5 seconds that correlates well with the video. The 1.0 overnight time I cannot rationalize and perhaps is a timing error on my part. The Restarts with a full housing are slightly faster at 1.1-1.3 which makes sense.
I'm concluding because of the small standard deviations in the data if there were a pocket of air created from an empty housing and/or empty oil galleries(s) that it doesn't influence time to pressure.
I welcome your thoughts and insights!
I came up with another test. I timed how long it takes to fill the Pentastar cartridge housing watching the Baxter Performance video. The housing is completely empty at the video start because one can see the cross at the bottom of the cartridge.
I started my watch at the first sound of the engine cranking to the time the lens is completely blanked out. The table below compares the results of timing the vehicle pressure gauge to greater than zero to the Baxter Video oil housing fill time. The average is .3 seconds longer on the timing the video fill.
One of the possible causes of the difference is starting the watch to the first sound of the engine cranking in the video. It is difficult. Timing the gauge is easier to synchronize because one hand hits the engine start and the other hits the stop watch button.
The 2.5 hour and Overnight with an empty housing were 1.4-1.5 seconds that correlates well with the video. The 1.0 overnight time I cannot rationalize and perhaps is a timing error on my part. The Restarts with a full housing are slightly faster at 1.1-1.3 which makes sense.
I'm concluding because of the small standard deviations in the data if there were a pocket of air created from an empty housing and/or empty oil galleries(s) that it doesn't influence time to pressure.
I welcome your thoughts and insights!
So in your testing data table, it looks like you did a cold start-up (on 11/9/23) after it sat overnight, which would allow the filter housing and system to naturally drain well, if it was going to drain. Then after the 1st cold start-up, you ran the engine just for a minute or less so the oil was still cold for another restart shorty later - correct? If so, that would have purged any air out of the filter housing and oiling system on the 1st cold start. Then you did a 2nd cold restart to see if purging any air showed a time difference ... correct?Good Morning ZeeOSix,
I came up with another test. I timed how long it takes to fill the Pentastar cartridge housing watching the Baxter Performance video. The housing is completely empty at the video start because one can see the cross at the bottom of the cartridge.
I started my watch at the first sound of the engine cranking to the time the lens is completely blanked out. The table below compares the results of timing the vehicle pressure gauge to greater than zero to the Baxter Video oil housing fill time. The average is .3 seconds longer on the timing the video fill.
One of the possible causes of the difference is starting the watch to the first sound of the engine cranking in the video. It is difficult. Timing the gauge is easier to synchronize because one hand hits the engine start and the other hits the stop watch button.
The 2.5 hour and Overnight with an empty housing were 1.4-1.5 seconds that correlates well with the video. The 1.0 overnight time I cannot rationalize and perhaps is a timing error on my part. The Restarts with a full housing are slightly faster at 1.1-1.3 which makes sense.
I'm concluding because of the small standard deviations in the data if there were a pocket of air created from an empty housing and/or empty oil galleries(s) that it doesn't influence time to pressure.
I welcome your thoughts and insights!
View attachment 188311
The time difference between those two tests was only 0.1 sec (less than the standard deviation), which tells me that if the filter housing was drained down over night, that trying to time to pressure first seen is not good enough to determine if the filter housing had actually drained down or not.
One thing you don't really know for sure is how far did your filter housing drain down over night, if any? Only way to know is to remove the filter to drain the housing completely, then do a cold startup the next day. And then do the 2nd cold start-up again after letting the engine only run a minute to purge any air from purposely draining the filter housing. That way you know for sure that you are comparing a drained out filter housing/oiling system to a full housing/oiling system on your engine.
All you need to do is just unscrew the filter cap enough to allow the "plug" at the bottom of the filter to completely drain the housing - let it drain for an hour with pretty warm oil, then reinstall the filter. Start it cold the next morning to get a time to pressure for a drained down cold system. Run the engine for a minute and shut it down. Restart the engine again a minute later and get your 2nd time to pressure for a full oiling system. Now you have a drained down vs full oiling system time to pressure on your specific engine. Have someone else start the engine so you can do the best possible at timing to pressure.
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