You are referring to the engine's pressure relief valve which is built into the engine. This valve opens up when the pressure exceeds approximately 100psi. The bypass valve on the PCX filter is designed to bypass at around 8-11 psi, just like the PLM filter. I've dissected plenty of filters, including the PCX and PLM filter, and it is obvious that this is a low pressure relief valve. There is no way that the filter media on these filters can withstand a pressure differential of 100 psi. As I recall, the highest bypass valve settings are on Volkswagen, and possibly some other German designed vehicles. These have a bypass valve setting of around 33 psi.

There are obvious differences of opinion on the virtues of bypass filtration and UOAs. I don't disagree that wear metals get filtered out by the bypass filter, but consider that many trucking fleets have significantly increased their engine life between overhauls using bypass filters, the potential benefit is significant. Time will tell whether I had a fantastic idea, or just spent less time on oil changes. In the meantime everyone can guess - and hope - that they're doing the right thing.

 

Sure they do, indirectly. Massflow through a fixed orifice is a function of the pressure and temperature. Once the oil is up to its operating temperature range, the flow really becomes mainly a function of pressure. As long as you have enough pressure, you have enough flow.

The point here is that UOAs are designed to measure how well the oil is surviving, not how well the engine is surviving.

 

slipstream444 Posted on Apr 1 2008, 05:50 PM
True.
That's why I asked: What's the alternative to get an idea on engine&oil condition, available to the "general" public, simple and relatively easy.
IMO: none.
A trailing measurement is IMO better then no measurement.


slalom44 Posted on Apr 1 2008, 10:18 PM
In the oil pump to be more precize
This means that even at idle (36psi at idle according to Service Manual with "old" style oiljets), the OEM oil allready filter acts like a non-full flow bypass filter.
IOW most oil will flow through the engine unfiltered and only a little will make it through the filter media.

 

mikegarrison Posted on Apr 1 2008, 10:43 PM
Yes.
In a way one can be "sure" that when using the recommended xxW-30 oil, at operating temp, and the pressure is what the service manual states, one has enough oil flow.
What the flow is, in cubic cm/second (or any other standard) is unknown.
You know as well as I do there is no "standard" xxW-30 oil, some a thicker some are thinner at 100C, think of the famous German Castrol.
So what the flow actually is at any time is a guess.

 

The Kleenoil system is a classic bypass filter. It receives pressurized oil (from the oil filter port or other high pressure port such as the pressure switch port), passes it through the filter, and returns the oil to the engine via dipstick port, oilcap, or oilpan drain bolt. According to their website, it diverts roughly 2 to 3 quarts of oil per minute. That is 2 to 3 quarts of oil that is not going through the galleries to the bearings & cylinders.

You can disagree all you want, but if you take 2 to 3 quarts per minute away from an oil stream coming from a positive displacement pump, you are going to get a reduction in oil flow and oil pressure. I don't disagree that the reduction in flow and pressure is negligible, but it is definitely not zero.

 

The bypass valve on your oil filter doesn't care what the pressure is outside of the filter. It cares what the pressure differential is between the two sides of the filter media. Your argument doesn't make sense.

 

Well, yeah, but that's a constant you can drop out of the problem as long as you are consistantly using the same formulation of oil.

 

Wow! I just checked in on this thread and can't believe the education I'm getting on oil filter systems.

First off, my limited knowledge of the spring pressure setting on the PCX-004 filter is based on Road Rage saying one time that it was pretty stout. The previous post that stated that it was 8-11 PSI seems like the industry standard for aftermarket filters, so I'm not surprised. But PureOne's seem to be mostly set at 12-18 PSI.

I have two questions:

1. Does the bypass of the oil filter occur when it senses a inlet pressure/egress pressure differential of 11 PSI, and then close again when the pressure differential drops below 8 PSI (normal filter flow)? Is that why the two values are given?

2. Since bypass mode should only occur when the oil is cold and thick (3 bars of water temp for VTEC comes to mind), or if the filter media is dirty/clogged enough to restrict flow, do you think Honda picked the right PSI spec for the S2000 filter? I tend to think it's safer than having a 12-18 PSI like the Purolator filters for the S2000.

 

INDYMAC: I don't know that 8-11 psi is Honda's specification, only that this is a common range for many filters. The PCX may very well be around 12-18 or even higher. I'm under the impression that each manufacturer has somewhat different ranges, which are designed around the filter construction and filter media used. My point was that the bypass valve is nowhere near 100 psi.
I can only guess, but I would assume that since it is a simple spring plate, it's designed to start opening somewhere in that range, thus would close at the same pressure. I can tell you that there will be some variation in the thickness of the steel spring plate, which will cause variability in the actual opening pressure.
That is an excellent point. I highly suspect that Honda came up with the PCX filter when they realized that the bypass valve was opening up in VTEC with the PLM filter. The PCX filter has significantly more filter media than the PLM filter.

 

On the site, the 2 to 3 quarts you are speaking is not sitting in the KleenOil system being filtered. It is saying that in a minute, 2-3 quarts pass through and back into the system. It is a continuous cycle - as oil is being redirected to the filter, it is being returned.

The KleenOil system itself will hold around half a quart of oil once the filter is saturated. To compensate for this, you simply add another half quart of oil to the engine. This is even better because that extra half quart you've added has that many more additives now protecting your components.