Thread End vs Dome End Bypass?

[ZeeOSix]

Originally Posted By: Gene K
Purolator built Mopar Mo-090 (Std) and Mo-899 (Metric) Filters used on the 5.7L Hemi and 4.7L OHC are thread end end bypass as well.

Interestingly despite the Mopar Mo-899 being interchangeable with the Motorcraft FL820S they are different with the Mopar having jelly bean style holes in the base plate instead of the round holes.


Purolator builds those filters per Motorcraft and Mopar design specs ... that's why they have a base end bypass valve. Purolator designs and manufactures their own branded "Purolator" filters, and those don't seem to have but maybe a handful (if that) filters with a base end bypass valve.

If anyone knows the filter number of an actual branded Purolator with a base end bypass valve, please post 'em up ... I'm interested to know which ones they are.

 

[4ever4d]

Originally Posted By: Jim Allen
I just got off the phone with an engineering contact at a well known corporation known for filtration. His specialty is engine oil filtration and I can only repeat what he said if he stays anonymous. He is one of my regular sources for my work and I want to protect the relationship. You can either trust me that I am accurately relaying his comments or not.

1- The biggest time to worry about bypass is a cold start because that's when all the junk in the canister has settled to the bottom and it's also the time when the DeltaP will be high enough to pop the bypass valve. FOr the most part, what was said above is true about the junk being held in the media when oil is flowing, but some will fall off and settle when the engine is shut off.

1A- Obviously the location of the bypass versus that settling point will indicate how much junk will get sucked up if the filter bypasses in the above cold start scenario. My source agreed that on a horizontally mounted filter, there isn't much difference in the amount of junk that potentially will be sucked up between a dome and threaded end bypass.

2- He said that "generally" a threaded end bypass is slightly better in most applications BUT he also said that there have been a lot of functional problems with the dome end valves on the market sticking open. He says it comes down to cost. The example he used is that it takes a $1.50 to make a threaded end valve that will equal the reliability of a $0.50 dome end valve. From there, you do the math.

3- My biggest question has always been how often does the average filter bypass. He chuckled at that and said something like "We'd all like to know that."
You can predict the most likely time this can happen but there are too many variables to make a general rule. As little as possible is the goal. He commented that bypass events are overall more likely at the end of filter life, when the unit is loaded and will have a higher DeltaP. Another comment was that here in the USA, we tend to engineer for higher filter efficiency and a shorter OCI, knowing the filter will be changed before the bypass events become excessive. In Europe, they prefer fewer potential bypass events, so generally have less efficiency, and longer OCIs. They also run higher viscosities and lower efficiencies are an aid in preventing bypasses in that event as well. He did quote an average that here in the USA, the average filter is changed with 45 percent life remaining but he didn't give me the source for that.



Very good information. Thanks for the time and effort involved. All the information here allows for a more informed decision.

 

[440Magnum]

Originally Posted By: ZeeOSix
Originally Posted By: Gene K
Purolator built Mopar Mo-090 (Std) and Mo-899 (Metric) Filters used on the 5.7L Hemi and 4.7L OHC are thread end end bypass as well.

Interestingly despite the Mopar Mo-899 being interchangeable with the Motorcraft FL820S they are different with the Mopar having jelly bean style holes in the base plate instead of the round holes.


Purolator builds those filters per Motorcraft and Mopar design specs ... that's why they have a base end bypass valve. Purolator designs and manufactures their own branded "Purolator" filters, and those don't seem to have but maybe a handful (if that) filters with a base end bypass valve.

If anyone knows the filter number of an actual branded Purolator with a base end bypass valve, please post 'em up ... I'm interested to know which ones they are.


I'll try to remember to check my stockpile of PL30001s tonight. I thought they were base-end, but I won't go on my memory- it could be that the metric thread filter for the 4.7 is the one I'm remembering as base-end. Also, one of the two filters used on the EDZ 2.4L is base-end, but again I'm vague on whether its the short filter for the normally aspirated EDZ, or the longer filter for the turbo EDZ.



I remembered that I have a photo of a dissected PL30001 on my photobucket site. Its clearly dome-end bypass. My memory aint what it used to be, but I do know that at least one of the models I use is base-end in a P1 branded version.

http://smg.photobucket.com/albums/v651/4...nt=104_5989.jpg

 

[mechanicx]

I can understand automakers like Ford and Chrysler wanting to specify a base-end bypass but why don't they do what GM did and put the bypass on the engine and filter mount? This allows for you to use a much more durable, precise and more expensive bypass than what you would put in a filter. I'd say they placed the base-end bypass in the filter out of cheapness but if they wanted to be really cheap they could've speced a dome-end bypass. GM has been doing it that way from almost the begining and I guess the other two just had to be different.

 

[ZeeOSix]

Only disadvantage of GM's filter bypass in the block is that it's set to around 8~10 psi - which is typically lower than most bypass valves designed in the filter itself. Therefore, need to make sure a free flowing filter is used, and that the filter is changed before it loads up significantly. SuperBusa's post about this very issue, and the bench test data Purolator provided to him tells the story on why it's important on a GM engine.

 

[Jim Allen]

Originally Posted By: ZeeOSix
Only disadvantage of GM's filter bypass in the block is that it's set to around 8~10 psi - which is typically lower than most bypass valves designed in the filter itself. Therefore, need to make sure a free flowing filter is used, and that the filter is changed before it loads up significantly. SuperBusa's post about this very issue, and the bench test data Purolator provided to him tells the story on why it's important on a GM engine.


This is something that had never occurred to me. I don't have a GM but my Ford 6.9L diesel has a built-in bypass valve and I better get to finding that opening spec and make my filter and oil choices accordingly.