Oil filter on the feed side

Hi Dan, I worked as a hydraulic engineer most of my life and contaminated oil was the cause of most failures, however the only filter on the suction side (feed side) was a strainer of 100/125 microns, anything finer and the pump would cavitation, ie trying to suck fluid that was not there. Cavitation will destroy a pump quickly. I do not know the rating of a diesel filter but suspect it to be 25 microns. In short I would not recommend using a diesel filter, as starving the engine of oil would lead to excessive wear. What I would suggest, if possible would be to place a magnet in the tank which will attract iron/ steel particles. Hope this helps.

regards Richard 

Dan,

The most appropriate location for a filter (as opposed to a coarse strainer) is in the scavenge line to the oil tank.  The scavenge location is best for a number of reasons:

• Keeping unrestricted flow to the oil pump is most important.
• Delivery oil feed from the tank relies partly on gravity.  In cold weather, the cold, viscous oil flow could be restricted by a filter, particularly if the filter is already contaminated and flow capacity reduced, thus starving the pump and leading to cavitation.
• Locating the filter in the scavenge line will remove debris before it enters the oil tank, keeping the tank cleaner.
• The oil pump will be able to push oil through the filter even when cold and viscous,  or the filter is contaminated.

Regards,

Andy

Other option is a magnetic filter that does not affect flow, if it's a steel frame then it should pick up most of the crud regardless of size.

Assuming the oil bearing frame is clean before filling for the first time (flushed well and passing the flushings over a magnet to check) and a filter is placed in the return line, then as long as future oil fills and filter changes are done hygienically, the system should remain free of large contaminants.  I assume the build will also be scrupulously clean as a matter of course. Anything ingested by the engine in use should be trapped by the return line filter.

If there is a frame breather In the system, a breather filter could be considered.

My T120 and Triton engines have a pressure side filter set up achieved by reworking the timing cover to send oil from the pump to the filter then back to the engine feed. I have not studied the oil flow in my Dominator closely enough yet to work out if that is even possible in a Norton. I am sure an expert will be along shortly.

Good luck with the build.

The '74 space-frame JPN had a special timing cover to route the oil from the pump via a spin-on cartridge filter then back into the engine. Might be possible if you have a CNC mill.

Otherwise, any filter has to go in the return line. As others have noted, a gravity feed is quite unsuitable for pushing thru a filter. And please don't use diesel fuel filters for engine oil; they are much finer filters and will introduce a lot of back pressure with engine oil. If the diesel supply gets blocked the worst that can happen is the engine stops ...

Hi Dan,

I just googled the Morgo filters and the website description states:

'This filter should only be used on a pressure feed, on classic bikes this would be on the return line or on the pressure output side of the pump.'

The filter canister looks pretty small, which is compact and light, and good for a track bike running synthetic oil, where the element may also get replaced frequently.  Without knowing the media rating, potentially 40 microns or less (smaller is more restrictive), if that is used with straight mineral oil or oil without ashless dispersants, there will be carbon particles in the scavenge flow that over time will contaminate the element more than metallic debris (unless the engine has a mechanical issue).  A larger capacity element could be beneficial for such oils, depending on how frequently the oil and filter are to be replaced?

Just a thought anyway.

Andy

Feed line filters are great, but as some above have said the supply has to be guaranteed clean. The reason being is that the feed line filter would protect the equipment being supplied but not the pump itself, debris from wear will eventually go through the pump. In most hydraulic systems the pump is relatively cheap and easy to change out, the equipment far more expensive.

If the pump is in the equipment then a return line filter would also be needed to protect the pump which is part of the equipment ie the engine. This is common practice in hydraulic circuits to help ensure the oil in the header tank stays in spec longer and prolong the life of the pump.