Oil filter

Time Warp said:

The filter in the return line was a band aid working with what was available for easy fitment or it would have been on the pressure side or between the pump and crankshaft ( Which if I recall correctly Jim Comstock did as a modification to his F.I bike)
With a pressure / scavenge oil pump one or the other side will be favoured for filtration either way.

Click to expand...

I would be surprised to learn Jim intervened the oiling system. This would require substantial changes to the timing side cover - to which benefit?? Also, a pressure drop at the feed side of a Norton twin engine is not desirable because pressure is marginal at the outset.
As F.E. points out, it doesn’t matter where the full flow filter is in the system as long as there is flow continuity.

-Knut

Time Warp said:

Of course any filter is better than no filter but you normally have it protecting the engine parts, not the oil tank.

Click to expand...

The clean oil that ‘protects the oil tank’ is the same clean oil that will then go on to feed the engine...

Where does the crud come from that endangers the engine ?

zefer said:

I have a all alloy canister type filter that K & N made back in the day with a washable 600 micron insert

Click to expand...

RoadScholar said:

Current standard filters are at 40 microns filtration potential (many are less). I am wondering what the bronze gauze sump filter is rated at?

Click to expand...

600 microns WOW is that OK?

Wix Number: 51032 Nominal Micron Rating: 10
Diesel fuel filters for my truck are now required to be under 5 microns

Fast Eddie said:

Where does the crud come from that endangers the engine ?

Click to expand...

The dirty oil spout while filling but from the engine's bronze, iron, steel from cams, bearing and bushes and products of combustion
Tough on the scavenge side of the pump

Oil testing has shown, in many lube oil tests with hydraulics, the oil being drained out is more filtered than as it comes out of the can/jug going in.....

I do support filtering the oil even if on the return.
A neno member and I finally split his MKIII crank for the first time and the sludge trap had only very slight sludge 160,000 miles!

I recognized where I got my filter info last year after checking out what concours put up.... Thank you Dave because it saved my days to come when I wrestle the booger to force an oil/filter change on it.

On most Triumphs, the oil feed is from the bottom of the oil tank and they have no filter. The sludge trap is definitely needed.

On Commandos with the oil tank on the right, the oil feed comes from the side of the tank, part way up. Any crud heavier than oil settles to the bottom of the tank. Add to that the oil filter, and you have little to no need for a sludge trap.

I've always split the crank and cleaned it whenever I've had a bottom end apart, but I've yet to find one that actually needed it. That's even true on Nortons without the filter. My assumption is that the majority of what would normally be caught by the sludge trap ends up in the bottom of the tank - I've cleaned Norton oil tanks from bikes without the filter with a LOT of sludge in the bottom.

dynodave said:

... from the engine's bronze, iron, steel from cams, bearing and bushes and products of combustion
Tough on the scavenge side of the pump...

Click to expand...

Dave, if the filter is on the feed side, the scavenge side of the pump has the same hardship.

My Crosland 673 16Mx1.5 spin-on oil filter is right after the oil tank and low behind the gearbox. If you guys saw my oil line routing, the "oh, that's wrong" BS would be deafening. System still wet sumps, so it must be Norton correct. When I put that filter housing on the bike, after the oil tank pre-pump was the suggested location. Made sense to me then, and still does.

Here in the USA I've tried a few times to find the O'Reilly's MicroGard version of that WIX filter, because O'Reilly oil filters are WIX and about half the WIX price, but have never been successful. The FRAM numbers in the oil filter list aren't carried by O'Reilly unfortunately. O'Reilly generally has better pricing on oil filters than performance houses, and they are down the street so that's where I go.

I still have 2 Crosland 673 filters left. When I get down to 1, I'll have to get serious and restock.

Fast Eddie said:

Where does the crud come from that endangers the engine ?

Click to expand...

Several sources. Blow-by introduces carbon particles which rank just behind diamonds in hardness. Short rides where the oil doesn't uniformly reach OT for long enough. Oil burning adds to the slurry. Sulfur, which mixes well with the water that isn't purged from short rides forms S2HO4 which, in turn, helps mix this witches brew and when the available water does purge increases the viscosity of the sludge...

Best

I have no problem ordering the Wix 51352 from fleetfilter.com with all of my other filters except aircraft. Since I have to cut my plane's filter open to inspect I have this tool, which I use to cut all the others open as well:

Amazon product ASIN B01N156ODN

Take a look at a couple of Dave Sundquist at Redline Norton’s builds - he has done some funky mods to the oil circuit.

Here’s one - go in about 14 minutes:

RoadScholar said:

Several sources. Blow-by introduces carbon particles which rank just behind diamonds in hardness. Short rides where the oil doesn't uniformly reach OT for long enough. Oil burning adds to the slurry. Sulfur, which mixes well with the water that isn't purged from short rides forms S2HO4 which, in turn, helps mix this witches brew and when the available water does purge increases the viscosity of the sludge...

Best

Click to expand...

Yes, agree to all of those.
But the question was in relationship to why it is deemed better to have a filter on the feed vs the return.
All of the points you mention are valid sources of crud, but they effect feed and return alike.

Just a thought on sludge traps - and disagree with me if you want:

The Norton twin crankshaft was designed circa 1948, when detergent oils were not really a thing. Sludge collected in the bottom of an engine and was not actively picked up by the oil - at least in a wet sump engine.
A dry sump engine is a different story, where the oil is actively pumped out of the engine, usually from a very low point in the engine. This means that you would be actively picking up the sludge and circulating it back to the tank. Hence the screens you see at various point in the engine, and why the oil intake is well above the bottom of the oil tank. And also why you need areas designed into the engine oil system where the sludge can safely settle out.

Fast forward to detergent oils. Sludge no longer collects in abundance at the bottom of the crankcase, or the sludge trap for that matter. It is picked up the detergent package in the oil and separated by the filter.

For the most part, the Norton Twin design right up to the Commando incorporates all of the features of an engine designed to operate on non detergent oils. That is not to say that they can't operate on detergent oils but it highlights the important need for an oil filter in the system when using detergent oil.

Also explains why the crankshaft sludge trap, for the most part, has been relegated to the function of your appendix - along for the ride, not really hurting anything, but not really doing much either.

Food for thought.

RoadScholar said:

carbon particles which rank just behind diamonds in hardness

Click to expand...

Are you sure carbon black is all that hard?

Is it used as an abrasive?

Carbon in cast iron acts as a lubricant, diesel oil goes black from carbon very quickly and stays black. Charcoal is soft and is high in carbon as is coal.

Even utilizing an oil filter on my return still allows for a small amount of sludge to collect in the bottom of the oil tank which I flush every 2nd or 3rd change. My old girl needs all of the assistance available to keep going in a healthy fashion.

jbruney said:

Even utilizing an oil filter on my return still allows for a small amount of sludge to collect in the bottom of the oil tank which I flush every 2nd or 3rd change. My old girl needs all of the assistance available to keep going in a healthy fashion.

Click to expand...

I had my oil tank out for a proper clean on 'y '74 850. Not sure it had ever been done previously. I had tried to siphon out the muck from above using a fluid suction pump...could not do it as the pump bottle would collapse under the immense vacuum being created That stuff was so thick!
with the tank out, it took lots & lots of jet spraying and bottle-washer brushing to get it all out. This of course accumulated even with the stock oil filter on the engine. So hard to imagine the crank sludge trap not being occupied.

Sludge in the bottom of the oil tank can stay there if it’s below the outlet, as far as I’m concerned.

But if you do clean the tank out, for God’s sake do it properly!

Tornado said:

So hard to imagine the crank sludge trap not being occupied.

Click to expand...

After 30 years / 30K miles when I did an engine overhaul, I found less than a thimble full of sludge. So little that I regretted having to take the crank apart to see it.

Tornado said:

So hard to imagine the crank sludge trap not being occupied.

Click to expand...

The tank and the crankshaft are in different situations. In the tank, half a gallon of oil can sit for months, with anything heavier than oil settling out.

The oil in the crankshaft will drain out while the bike is parked.

If I were to clean mine and doxy her all up like some of you( not pointing fingers or calling out names mind you) I would be a lot more than mortified at what I find sloshing about inside my lovely old machine.... That wonderful motor is worse than a sewage treatment plant for collecting and producing nasty crap.