Oil Filter Internal Bypass valve

[QFAD]

Ok Gents,

As it has been a bit quiet on the posting front, here is a starter for 10:

A question related to oil filters – I know the good old Purflux LS131 has provided many years of good service; but by way of curiosity I was looking at oil filter build reviews and alternatives etc.

So you have two oil filters of the relevant size and burst pressure, but their internal bypass valves open at different pressures; one at 16 psi and the other at 30 psi (I could not find any info related to the bypass valve relief pressure for the LS131).

So which is more desirable in the context of our A series engines?

[Lomax76]

Hi,
Best configuration for our engines must be if I'am not mistaken:
Reverse Lock Opening Pressure bar 0,12
Bypass Valve Opening Pressure bar 1,5
But not sure Purflux can provide thé secs
Closest will probable be the MANN-FILTER W 712/9

[QFAD]

Hi Lomax76,

Regarding the oil filter internall bypass valve - (to relieve the differential oil pressure on the inlet/outlet side of the filter matrix). Thankyou for your information - 1.5 bar (21.75 psi) does appear to be considered the usual relief pressure

I was trying to understand the consequences of lower lift pressure of 16 psi compared to the higher lift pressure of 30 psi - benefits?

I thought the higher the lift pressure the more the matrix would continue to filter the oil when the marix is partially blocked, rather than the oil flow just bypassing the matrix and allow dirty oil to pass through back into the engine.

I could not find a satisfactory explanantion on the net.

Steve

[Jimmy Cooper]

Used to have these "tech spec" chats on the Caterham 7 site too. Surely the bypass circuit only comes into play when an engine is either got dreadfully dirty and is overdue-a-change of oil creating clogged filtration within it or something has gone stratospherically wrong with that engine's internals so it's not a lot of help anyway?
If, as most of us do I'm sure, we change the oil and filter regularly then is there a problem with either a 16 or a 30psi lift?
Maybe I'm missing the point..........................but I won't miss regular oil and filter changes!

[Lomax76]

Hi,
I think Jimmy is right nothing to worry to much as long as the oil and filter are change on regular basis with adequate components.. the More important to make sure the reniflard is as per specs and is running as such..

However there is here something below that will may be help
http://freeasestudyguides.com/graphics/ ... valves.png

[QFAD]

Hi Guys,

I appreciate your point and totally agree - regular oil and filter changes is a given. As our cars are not a 'commercial' vehicle having to earn their keep, economics is not the critical criteria. Mine is treated to new quality oil and filter every 3000 miles or annually. Infact in many ways it is over serviced - I even change the gearbox oil annually. The suspension, drive shafts and steering etc are all lubricated at the beginning of every season or more often if the mileage requires it.

I guess our cars are projects that are never really finalised - there are always new ideas. I'm currently working on an alternative headlamp mounting system as the Lomax U frame has snapped (internal corrosion - I also think it looks ugly), hence my interest in the Le Patron method of mounting.

I just wanted to understand the thinking behind the wide range of bypass vale relief pressures.... not that it has any influence on my filter choice.

[Geoff Ryall-Harvey]

Coincidentally, I've been talking to a Pontiac specialist in the USA about changing the canister oil filter set up on my hot rod to a spin-on arrangement. He tells me that he no longer fits oil filters to his high performance engines, he has a bypass pipe and he just changes the oil every 1000 miles. This is because there are no issues with valves or poorly performing filters and no restrictions to flow. When you think about it, 1000 miles is probably the annual mileage for many "project" cars.

[Lomax76]

Well,
I might try to explain.
With cold oil:
the by-pass valve low pressure preference is given to lubrification thus particules will not be filtered
the by-pass valve high pressure preference is given to filtration thus the oil flow will be less.
Hope this will help.

[QFAD]

Hi Lomax 76,

I get the filtration/lubrication preferences aligned to the oil bypass relief pressure.

As we are (mostly) over-servicing our cars (regular oil & filter changes) lubtrication and not filtration would be the preference for us, especially as noted given the relatively high oil pressure when starting from cold and the of course the cooling function of the oil (flow) passing through the cylinder heads (exhaust valve).

All good stuff...