Is the Purolator bypass valve design all that bad???

[davefr]

In reading the threads on Purolator it apperas that the bypass valve location is a "bone of contention". I have the following questions:

1. How often does a filter actually go into bypass mode?

2. Does the Purolator design really sweep dirt back into the crankcase in bypass mode?

3. If the Motorcraft version of the Purolator design is superior, why didn't Purolator adopt it?

 

[Virtuoso]

1. We don't really know.

2. It has the possibility of doing so.

3. Probably more expensive to make.

 

[T-Keith]

I pretty much agree with Viruoso.

My answers:

1. I haven't seen any really convincing testing to prove exactly how much, and of course it no doubt varies per vehicle. From what I have seen my guess is not very often, perhaps only at startup.

2. The logic seems OK, but I'm not convinced it makes that huge of a difference. With the pressure and flow through the filter it seems likely to happen with any in-filter bypass if it does at all. Media is designed to trap the "dirt" so ideally it should not happen at all.

3. I don't think that they feel it justifies the cost, otherwise they would do it since they have to make them that way already for Motorcraft. It would be interesting to see if the Champion filters Ford uses on the assembly line have the bypass at the front.

To me, a bypass in the engine makes a lot more sense, but some cars just aren't designed that way.

-T

 

[Brian Barnhart]

quote:

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It would be interesting to see if the Champion filters Ford uses on the assembly line have the bypass at the front.

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The OEM Champion that came on my 2002 Ranger had the front end bypass. But except for the K&N and M1, I've found few, if any, other Champion filters that have front end bypasses for Ford and DC applications. It seems most manufacturers, including Purolator, Champion, Wix (Napa Silver), and Fram put filter bypass valves in the closed end on their lower cost filters, and in some cases, even their premium filters.

 

[gudmund]

not all NAPA Silvers have the bypass at the closed end. you have to look at them, they have a mix of everything. The 21516(silver) that crosses to a Motorcraft FL400s has the bypass at the treaded end just like the NAPA1516-inside they look the same except for the backflow being black rubber instead of silcone rubber in the NAPA Gold & FL400s. Whats really odd is Purolator also makes a cheaper filter called POWER-FLO that is built the same inside as the Motorcraft with the bypass at the treaded end. The backflow valve is black rubber and can't say if the paper is the same but all else looks the same.