Oil filter on oil return

[shaunstaples]

I’ve been doing some work on fitting a screw on filter to the oil return pipe.
I’m not really sure about the Bypass pressure, got thinking about the bypass valve operating at the pressure value, when its equal to the difference in pressure across the oil filter paper.
On a common 8psi bypass pressure filter when the outlet is just a return pipe back to the tank, the pressure will be next to nothing and the inlet pressure on a cold morning, could easily be greater than 8psi, then the valve should be open and the oil would be unfiltered.
But then when it’s fitted on the pressure side then the crank and overhead feed resistance should generate the pressure, then only bypass when the filter inlet pressure increases 8psi over the engine pressure.
So will it be more important to have a higher bypass pressure value to overcome the higher oil pressure when cold, when it’s fitted on the return side?
Another thing I was thinking was the effect of low oil pressure by a worn engine, would it be easier to reach the bypass pressure due to the filter pressure overcoming engine pressure easier?
Sorry for rambling on, just wondered what anyone thought? kind of over thinking a bit now, but want to make sure the filter is doing its job.
I did a few searches for past posts, but all I found was the valve opens when the filter is blocked.

[dave16mct]

Shaun my head hurts now after trying to read your post, sorry! I've fitted them to quite a few bikes including T140 which had a high capacity oilpump. Also a friend had the pipe blow off his even with jubilee type clamp fitted. The only thing that annoyed me is the in/out pipes are usually 3/8" which makes it awkward with our pipe sizes. I've just found that Andover Norton sell Commando filter heads in both 3/8 and 1/2" sizes so I'll get one of those next time. I think you should just fit it, definately only on the return side, and forget about it. Fit a new one every year and it won't give any trouble. By the way I'm fitting this one on my G11 down in front of the rear wheel as suggested by a member on here. Much easier to change and leaves more space under the seat. The oil pipes have an easier run too.
Dave

[ChrisTheChippy]

Hi sorry to but in on this thread. I too plan to fit a cartridge type filter this winter . I already have a wet sumping valve fitted linked to the ignition switch . Do you think that will make any significant difference to the flow of oil the pump has to push round ?

[dave16mct]

I doubt it when you look at the size of holes in the oilpump your valve size will be bigger than those. I've just bought a '63 CSR which I know badly wet sumps so I'll be fitting a tap as well as one of the commando 1/2" outlet filter heads from Andover Norton. The last tap I fitted was a gas tap which was full bore when turned on. The only restriction was the 3/8" pipes on the filter. It has a long handle which I arranged in line with the kickstart lever so It can't be started without turning it on.
Dave.

[shaunstaples]

Haha welcome to my world, yes I've been looking at those and the plain pipes put me off. Duncan sent me a link to Andover Norton and they had barbed pipes, I almost bought one but went for one with threads instead of plain pipes for flexibility. I still might end up under frame yet.
Mine has a 1/2" sleeve over the 3/8 pipe into oil tank which caught me out as it was under the rubber tube and I measured it 3/8".
It'll end up with 1/2" inlet and 3/8" out to tank.
I know if it does bypass it still has the felt filters and gauze, just want to try and get it right and get all the oil through the filter.
The filter I've gone for is for a Dacia (MANN W77/3)

[shaunstaples]

Think the return pipe into the tank is 3/8" so its probably 1/16" wall thickness and 1/4" inside, and the pump gives a great return as it is.

[MalcW]

I can't comment on the pressure requirements, all can say is that my 650 has a cartridge oil filter on the return side, hidden under the seat, and it's been working fine for nearly 10k miles (not all on the same filter, obvs).

Malc

[ChrisTheChippy]

Thanks for the reply and great advice as usual. It's very reassuring sometimes just to ask the question puts the mind at rest.

[dave16mct]

Here's mine on the G11 I'm rebuilding:

Dave

[shaunstaples]

Thanks Malc, I'm sure it will be fine as yours has been, just got thinking about it and find it hard to explain what I mean sometimes.
That looks neat Dave, and it should be easy as you say to pipe up from there.

Well started my bike up with the filter and a 15psi pressure gauge inline on the return.
I tried it first with the existing SAE 50 for a starting point, I expected it to be higher than a multigrade would be but from Cold shot right round to the needle zero stop so quite a lot over 20psi. Left it running till oil was warm and pressure was still hovering at 14psi on tickover.
I drained the sae50 and filled with some 10w60 multigrade I already had. After lunch the engine had cooled down, I repeated Cold was Just over 15psi and hot was 4psi. I'm happy with that and the filter has a Bypass value of 18psi so should be all good, unless I take to thrashing about before oil is warmed up.

The other positive thing is that the engine oil pressure is improved with the multigrade. With the SAE50 after a few miles when the oil was just warm the needle would just flicker on tickover and couldn't hit 20psi revving it. With the 10w60 its just over 10psi tickover and between 35-40 hot.

From what Ive seen today If you were to fit a filter with a bypass pressure of 8psi on the return, while still using Straight 50 the filter would probably be clean when you changed it?

Went to put tank back on and but put my finger in something soggy where the seat recess is, looks like P.O. has used (and disguised ) a petro- patch. Has anyone had any success with the tanks from India?