When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
We have seen lots of issues with the 6637 style filters being too restrictive and can literally suck the intake boot closed. I know everyone online runs them, but thorough testing has shown they are very restrictive and clog up very quickly. We recommend the AFE BHAF, here is a link.
Awesome write up... the PDF charts really make it easy to follow.
I have not had time to completely read everything... been trying to skim through during breaks.
I do have one question or maybe I should say a thought... It would be cool to see the performance difference between each filter BRAND NEW vs READY TO CHANGE. To see how the data changes as the filter starts to clog up.
Would also be cool to do the same tests with a slightly bigger setup pushing 35-40psi of boost to see how much vacuum increases.
Coming from the standpoint of someone that diags turbo issues all the time... I have had many customers eliminate turbo problems by getting rid of the 6637 filter and change over to a higher flowing filter. I have seen it cure turbo surge, turbo bark, high egts, intake boots sucking closed on aftermarket filters, etc. I have not been able to narrow it down to any certain "brand" because I know there are a lot of variations of 6637 filters. But we keep a running log if issues customers have had and we have seen the 6637 filter cause enough issues that it is one of the first things we check now when a customer reports a turbo performance issue on a 7.3. But that is not to say the everyone that runs a 6637 filter will have issues because we have many customers running them with no problems.
I know "turbo dusting" and/or "engine dusting" can be a hot topic from "high flowing filters". From our in house testing, customers, and turbo repairs over the years we never see turbo dusting issues from "high flow filters". What we always find is an issue where the turbo is sucking air around the filter or bypassing it. For example flat k&n drop in filters are often taller and when you snap those air filter clips down they often break the plastic and ends up leaving an open gap. Or someone who runs a filter so long it gets a tear in it and sucks dust/sand through. Just food for thought
Looks like a little more background may be necessary. I first switched to the Wix 6637 in August 2020 according to order conformation emails and the pre filter was installed at the same time. Then in September 2020 I bought the new CHRA w/ the billet 5+5, so at the time the turbo was "upgraded" the filter and sock were only a month old. Fast forward to February 2021 I ordered a new Wix 6637 and that's when I noticed the difference between sock and no sock. So the first filter and sock were only around 6 months old, now I do drive a lot of dirt roads daily so I wouldn't expect to get more than a year at best from a filter but still the difference was surprisingly noticeable. I do think some kind of pre filter would benefit my circumstance but until reading about the pantyhose idea I wasn't sure what would be a suitable replacement because I wasn't going with the Filter Wears again.
Thanks Jason, I appreciate it. I read that post, but must have missed that last detail.
Quote from link Jason shared with us above:
Originally Posted by Charlie at KC Turbo
We have seen lots of issues with the 6637 style filters being too restrictive and can literally suck the intake boot closed. I know everyone online runs them, but thorough testing has shown they are very restrictive and clog up very quickly. We recommend the AFE BHAF, here is a link.
The quote from the second link provided by Jason above:
Originally Posted by Charlie at KC Turbo
Coming from the standpoint of someone that diags turbo issues all the time... I have had many customers eliminate turbo problems by getting rid of the 6637 filter and change over to a higher flowing filter. I have seen it cure turbo surge, turbo bark, high egts, intake boots sucking closed on aftermarket filters, etc. I have not been able to narrow it down to any certain "brand" because I know there are a lot of variations of 6637 filters. But we keep a running log if issues customers have had and we have seen the 6637 filter cause enough issues that it is one of the first things we check now when a customer reports a turbo performance issue on a 7.3. But that is not to say the everyone that runs a 6637 filter will have issues because we have many customers running them with no problems.
The challenge is finding a chock with a tight enough radius for the 6637 to nest in, while at the same time finding a chock that is wide enough to cover the length of the 6637.
Typically, chocks with a tight radius that would "hug" the 6637 well are also smaller, so it might take 2 or even 3 chocks arranged side by side in a row in order to get good coverage.
I did find one wider chock that matched the radius of the smaller chock, but the wider chock was made taller too, so that presents a problem with hood clearance.
The challenge is finding a chock with a tight enough radius for the 6637 to nest in, while at the same time finding a chock that is wide enough to cover the length of the 6637.
Typically, chocks with a tight radius that would "hug" the 6637 well are also smaller, so it might take 2 or even 3 chocks arranged side by side in a row in order to get good coverage.
I did find one wider chock that matched the radius of the smaller chock, but the wider chock was made taller too, so that presents a problem with hood clearance.
I thought he misspelled CHUCKING as in he was going to defenestrate the filter.
Well, that is what I get for creating a thread while gathering my thoughts on the content and rushing through the title... For the sake of sanity and maintaining a sense of humor, the thread title will remain "CHOCKING" a 6637! I am man enough to admit when I make a mistake. I think this is the only mistake I made today though, so good day! So far anyway!
I'm still intrigued by these reports from FTE'rs and the testimony from Charlie though.
If the 6637 in itself can have "insufficient flow". What about all the industrial diesel applications that run dual paper filters, a inner and an outter filter. They are usually of the same design but with one filter slid inside the other. I think people tend to run them over their change intervals as they take quite a bit to "look dirty". When in actuality when they start to change colors they are loaded up with dust and start to impede flow. Maybe a good test would be to weigh a new filter and then weigh the same filter when it is dirty to find out how much dust it traps.
If the 6637 in itself can have "insufficient flow". What about all the industrial diesel applications that run dual paper filters, a inner and an outter filter. They are usually of the same design but with one filter slid inside the other. I think people tend to run them over their change intervals as they take quite a bit to "look dirty". When in actuality when they start to change colors they are loaded up with dust and start to impede flow. Maybe a good test would be to weigh a new filter and then weigh the same filter when it is dirty to find out how much dust it traps.
Ooo that sounds fun. I'll try to remember that for my next filter change, which by the look of things won't be to much longer.
This is just my opinion, as humble as it may be. My thoughts are this... When I ran the AIS for many years traveling cross country and towing with the modified stock turbo, it did very well. But, the filter media difference between the AIS and the Donaldson blue 6637 is vast. I cannot speak for the white 6637 as I have never owned or seen one up close other than the ones in places like Tractor Supply.
I feel that a thin material like a porous pre-filter is a great way to extend the life of a Donaldson blue 6637. I know I frequently clean my pre-filter cover when changing oil or performing some other maintenance task due to pollen, dust or whatever. I feel that if these "contaminants" were being allowed to imbed themselves in the Donaldson blue 6637 filter media or folds, the cleaning task would become much more cumbersome and costly over time. In my opinion, the pre-filter allows for the life of the 6637 to be extended greatly which is a win for me. Easy maintenance and lower cost over time.
I have had this Donaldson blue 6637 on since December of 2018 and it looks new still. I cleaned it up when I had the turbo out a couple of weeks ago and it was still very clean. It needed a good "shake", but for the most part it was in great shape. Granted COVID hit the country last year and our traveling with the truck and 5th wheel was severely degraded, but we still managed to get up to Philadelphia, over to the beach 3 times and many sub-100 mile trips with the truck and 5th wheel since December 2018.
It is interesting that you also notice slightly lower boost with the cover on... If you had to take a WAG, what sort of number would you put on the "slightly"? Would it be .5, 1 or 3 PSI and when are you noticing this lower pressure? Is it at WOT, cruising at 2000 RPM or across the entire range?
I cannot say if the pre-filter is actually a pre-restrictor or not. Frankly, I have never ran the truck with the Donaldson blue 6637 without a pre-filter.
Interesting... Perhaps my thinking on this pre-filter is skewed and I need to reevaluate...
That makes sense. No more than I've driven my truck the last few years, filter longevity hasn't been a concern. A pre-filter would certainly help them last longer, though.
The difference I saw was only at WOT, and was just a pound or two on the gauge. The RR covers at the time were fairly thick. I have one of the new super thin ones on my 4runner. I can't imagine they'd offer much restriction.
@Y2KW57 , due to your very detailed response with visual aids, options, scientific explanations and "3 paragraphs" of thought, I figured it out!
Despite the appearance of the "BIG YELLA" chock holding the 6637 filter in place looking "too large", it fits perfectly!
It is easy to insert or remove in an emergency situation due to it's width and "tacticool" style handle. In addition, it simultaneously has a narrow and broad radius (unbelievable right...) that enables it to fit perfectly. I tested this fitment at up to speeds of 102 MPH (FORScan data log proven) with the hood up so that I could see the articulation or movement of the "BIG YELLA".
No video footage was taken though as it was a "Top Secret" location on a closed course, of course. Double Top Secret actually, but whatevs... No big deal...
I have decided to use a high visibility road cone to keep pedestrians, gawkers, service animals and BRAH's away from the highly specialized and super duper specialized (double special) "BIG YELLA" chock while it is engaged in it's primary mission. Which is also a "no fail" mission, obviously...
I was able to secure 5 more of these chocks as prototypes and plan to use my arsenal of pew pew's to safeguard them.
I thought you may be interested to see that I analyzed the problem, tested a solution and put the solution into action with great results, all thanks to you for getting the ball rolling, or should say "chocking" the ball...
That is a relief to know that you are taking responsibility to mitigate the additional safety hazard that the filter sock/cover over the 6637 presents.
The smooth surface area of the cover reduces the rolling resistance of the filter, which without the cover has pleats that can engage with the undulating surfaces.
Especially at unimproved campsiites, such as the grassy knoll at SSJ's, where the open filter pleats can mesh with grass (and mud), which lessens the filter's ability to roll, and thus reduces, if not eliminates, the need for a chock.
But those filter socks cover up the pleats, thus covering up the largest benefit of the filter as originally designed.
So not only is there less filtering surface area exposed to incoming air to catch dirt before becoming restricted, there is also less rolling resistance.
As such, your thread on filter chocking could not be more timely, as this realization becomes known.
That you shared your secret solution with the members of FTE is likely greatly appreciated, both now and in the years to come, by those who may not even realize that the problem has come full circle, in a sort of roundabout manner.
Thank you for your vote of confidence, it means a lot!
Coincidentally, I was at the SSJ Ranch with Jason yesterday and we walked (read as road the golf cart because we are too lazy to walk) the "grassy knoll" area and contemplated the 6637 and the ability to "chock" it. Turns out, we agreed that the pleats are covered by the smooth surface... cover... Although, after much deliberation and head scratching (butt scratching as well) we decided that panty hose (color is irrelevant) may be the perfect solution to having a pre-filter and the rolling resistance of the filter as designed by SpaceX and aliens.
The conversation depicted above is for entertainment purposes only and never took place.
Apparently... Panty hose are known for providing a smooth and attritive cover, but also letting the covered object get the job done.
