Oil Filters

[KiwiGF]

My son disabled the bypass valve on his firebird (I know it's a car) so that all the oil had to go through the filter.
One day he had no oil pressure, he checked everything to find out what was wrong. In the end he changed the oil filter and the oil pressure returned. The filter had only done 3,200 miles.
That means that past 3,200 miles none of the oil was being filtered.
From then on we have always changed our oil and filters every 3,000 miles.
So, how do we know how many miles a 2cv filter on a BSA is good for ?
Roy.

Unless you stick a pressure gauge either side of it you won’t know, it’s an act of faith I suppose. Even then there will be variances between brands. There will be filters that are better at filtering small particles out that are more prone to getting clogged as a consequence, and some with more surface area of paper that will be less prone to clogging, and some that only filter big particles out and will never clog. The only sure thing is that a filter will almost certainly do SOME good.

I don’t care if a filter has a bypas or not. It will get changed at max 1500 Miles anyway, surely any filter will not get clogged in 1500 Miles! (But even that is an act of faith).

[RogerSB]

So if the bypass filter operates at 10psi, then the bypass will operate when there is 50psi one side of the filter and 40 the downstream side, or 30/20 or 20/10 etc etc.
If there is a restriction downstream of the filter (say in return pipe the inside the tank) then this will raise the pressure equally throughout the system so BOTH sides of the filter, thus not affecting the bypass operation at all.

Kiwgf, I had to read that over and over to understand it, even though I know you explained it very well. This is something that has puzzled me for some time and I 'somehow' got a certain way of thinking about it in my head so I thought this oil filter topic was a good time to air it. I 'think' I understand it now.


So just to sure, talking oil return pressure from engine to the 'IN' side of a spin-on remote filter: I somehow got it in my head that if the incoming oil pressure to the filter was greater than the designed by-pass setting it would be sensed and would automatically trigger a by-pass of oil, regardless of the condition and effectiveness of the filter element. But from what you say, in reality it actually senses the pressure either side of the filter element (i.e. in and out) and if the difference is not greater than the filters by-pass setting then all will be well .


Regarding Roy's question and duTch's reply: If the filter became blocked surely you will still see oil returning to the tank because of the filter's by-pass feature . Also, as far as I can make out if a filter does get clogged up it still isn't black and white and you can get some oil by-passing the filter element and some still going through it - until it gets fully blocked and then all oil is by-passed. Correct me if I'm wrong.


And why does my text keep going tiny ???

[bsa-bill]

back in the day of Citroen CVs and many others using mineral oil and paper filters oils were changed at 3,000 miles 5000 at a stretch (correct me if my memory is wrong), some used to change the oil but change the filter every other oil change.
 this is probably more than most of us do in a year so an annual change should be safest bet

[worntorn]

I cut one of my 850 Commando filters apart after it had been in for two oil changes. It was nowhere near clogged, just a little discoloured. It did have a few tiny flecks of metal here and there.
It seemed like changing the filter every four thousand miles might be overkill, but it's not a big cost or hard to do.

Glen

[RogerSB]

I suppose today we all do our best to save our BSAs from any catastrophe, not only to conserve them but it’s very expensive otherwise.
I rode Golden Flash’s in the mid 60s to mid 70's as everyday transport. One of them (the one in my profile photo) I rode at least 400 miles just about every weekend for over a year, unless I was home on leave, to travel back and forth from my unit’s barracks in Portsmouth to see my girlfriend in Plymouth. In those days I didn’t have the time or the inclination to change the oil regularly, probably once a year and topping it up in between. There was no fitting of filters in those days either and my Golden Flash always performed superbly. One thing that did always strike me on those journeys was that after about 50 miles the engine would seem a lot quieter and would just hum along doing about 65 - 70 mph where I could on the roads then. It never let me down - nor did it start knocking and banging.

[Greybeard]

And why does my text keep going tiny ???

So, I'm not the only one having that problem! I write most of my forum stuff using this Android tablet and it often inserts a tiny size font tag when I'm editing. Have to Preview and take out the tags. Flipping annoying.

[RogerSB]

See pic. I've found that by highlighting the text (you can select all the text if easier) and then clicking this symbol it changes to the correct size.

[Greybeard]

Yes, I guess that should work; it's the 'Remove all formatting' button; I'll use that next time it happens. Thanks for reminding me about it!


Apologies for going off topic.

[chaterlea25]

Hi Roy and All,

The filters we use on our BSA's are designed to filter quantities of oil that are measured in pints/gallons or litres per minute 
The capacity of the BSA pumps is tiny by comparison, so in my opinion the filters do not get to anywhere near their
designed filtration capacity before owners change them

John

[Colsbeeza]

That's interesting John  (A101960) that the Paul Goff Filter fits into the flat lid toolbox. That would be the EMGO little black filter.? Many bloggers say they won't fit, but consider me enlightened. (Not that I have a flat lid toolbox). Is it bolted directly to the back of the toolbox to give enough clearance.?
One comment I would make about the filter bypass valve. Some filters do and some don't have them. However, they would only ever open when the filter is near blocked, as the A10 scavenge pump flowrate is so low, as others have said. The pump is capable of high pressures though, and if the filter was blocked, the pressure would build up until the pressure forced the valve to open. So the pressure rating of the filter bypass has nothing to do with the pump oil pressure until the filter gets blocked.
In response to another question, I also read that on the early A7's, the oil pump passes 126.6 pints per hour and the return pump passes 177 pph at 5000 rpm which may help. That came from a blog and was reported to have been said by Bert Hopwood, BSA's Chief Designer to a reporter from "The Motorcycle". I don't know if the later pumps had larger capacity before the A65 came along.
Cheers Colin

[duTch]

 

....That's interesting John  (A101960) that the Paul Goff Filter fits into the flat lid toolbox. That would be the EMGO little black filter.? Many bloggers say they won't fit, but consider me enlightened. (Not that I have a flat lid toolbox). Is it bolted directly to the back of the toolbox to give enough clearance.?.......

 I'm using a Emgo jobby one, and it is a bit shorter than the original one (origin unknown)...works better for me on my custom-ish Plunger

[TimK]

..That's interesting John  (A101960) that the Paul Goff Filter fits into the flat lid toolbox. That would be the EMGO little black filter.? Many bloggers say they won't fit, but consider me enlightened. (Not that I have a flat lid toolbox). Is it bolted directly to the back of the toolbox to give enough clearance.?.......

The picture below shows one of Goffy's filters fitted in a flat top toolbox. I didn't use the supplied stencil to cut the holes as that would have required me to cut the rear mudguard as well. I also had to omit the supplied spacers  or the filter would have sat too proud to close the lid of the toolbox. I found that I could achieve a bit of clearance behind the filter using a couple of washers. I know it's going to *** oil all over the place when I change the filter, but a rag will sort that out.

Cheers

Tim

[muskrat]

G'day Tim.
I think if you take the oil line off where it exits the motor a few minutes before you remove the filter it will minimize the mess.
Cheers

[TimK]

Muskrat said

G'day Tim.
I think if you take the oil line off where it exits the motor a few minutes before you remove the filter it will minimize the mess.
Cheers

I like that idea!

Cheers

Tim

[duTch]

...take the oil line off where it exits the motor a few minutes before you remove the filter it will minimize the mess....

 Don't disagree with that,  but when I installed mine I tried to locate it so it was vertical (screwing up onto the head) but no way...ended up horizontal.
 No big deal, I find it just as easy to just undo the two 5/16"unf  bolts holding the shebang on and drag it out and let it drain however...

 **edited** forgot to add the pic for filter orientation... now done