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..positive oil filter.

4K views 30 replies 12 participants last post by  lovecuba 
#1 ·
Hi,just getting to the final stages of fitting an oil filter to the feed side of the 650...I'm using hydraulic connectors even tho it'll only have a max pressure of 60 psi.This will be mounted on a pre & unit 650..cosmetically,it'll look like stock(almost)..waiting for the timing covers to come back from the polishers but here's a couple of photo's for now..
 

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#3 ·
I still see no advantage using the feed side for a filter over fitting it on the return.My oil is filtered on its return from the engine so fresh filtered oil is then pushed into the engine by the feed side.
A positive feed filters just before it enters the engine and returns unfiltered oil to the tank.
So,at start up,my oil tank feeds clean oil to the engine
Positive filtered engine feeds oil to the engine and filters it at a nearer point.
Is there more to it than i can see ?
Surely,if the oil is filtered at any point,the filter is doing the same job.
 
#6 ·
I am also inclined to think its pushing the capabilities of the piston pump on the twin, they are not exactly high flow pumps at the best of time and giving it more work to do by increasing the pressure head it has to overcome doesn't sound good to me.
 
#7 ·
I might be an expert on this :laugh2: In the past I modified several vintage auto engines to accept modern full flow filters. They were plumbed in right after the oil pump like every modern car/truck and many bikes on the road today and the engine shown in this thread..I actually ,measured the oil pressure before and after the filter..About a 3 PSI drop after the filter with an oil pump flowing about 6 gallons per minute at about 2000 rpm....Triumph might flow a pint or so a minute? Do new rod bearings with tighter clearance overload the pump compared to more worn bearings?
As a side note, every tight 90 degree fitting lowers pressure about 2-3 PSI...
The OP says 60 PSI.....In my opinion 70 psi maximum with warmed up oil might be better if the engine is run at high RPM's ?
 
#9 ·
Hi Guys, I did a lot of study on this before fitting the Motao frame sump filter.

I worked as a Porsche tech for a number of years. The 911 has a large spin on oil filter on the oil tank which is in right rear fender. The filter is on the return oil system, not the feed.

Early Triumphs had a insert type filter on the return line.

Wet sump motors have a filter on feed side, since there is no return side. Oil returns to sump (oil pan) by gravity.

Some motors like the early 356s had by pass filter so only a tiny amount at time got filtered.

Like our bikes old air cooled VWs just had a strainer screen. Not too good.

The piston pump fitted to our bikes is surprisingly efficient, has very little leakage by the pistons. Has great suction power & can pull over 20" vacuum. I learned that doing testing on the Motao filter.

The thing that concerns me is no by pass to compensate for a clogged filter or resistance to flow through the filter.

At the same time any higher resistance to the oil flow puts more strain on sliding block for pump.

On my Motao if it clogs my motor gets no oil. My warning is oil light comes on, by then I'm sure damage is done.

I've torn many blown motors apart. They tend to have metal chips everywhere no matter the filter.

At the end of the day all the above oiling systems work good. It doesn't seem to matter where filter is. No question a real filter is better than only a screen.

I can say for sure my oil is visibly cleaner longer after installing Motao filter.

But.... will my filter actually make motor last longer??? That I don't know.

Fun stuff!
Don
 
#20 ·
Hi Guys, I did a lot of study on this before fitting the Motao frame sump filter.

I worked as a Porsche tech for a number of years. The 911 has a large spin on oil filter on the oil tank which is in right rear fender. The filter is on the return oil system, not the feed.

Don
And some dry sump engine have filters on the pressure side like the late model Z06 Corvettes and the 70's Honda 750...
 
#11 ·
I still see no advantages to the filter being on the feed side when the fitting on the return side is so easy.I see Don mentions the possibility of the filter totally blocking and no oil getting through.The Filter i use has a by pass if the filter gets blocked so never a problem if that were to happen.
I have seen a Ford car engine run for 60,000 miles on the same oil and filter and came into the garage as it had a misfire caused by water sitting in the spark plug pocket in the head.It was still in good order and after advising the owner that the car needs regular servicing,it was serviced and still ran very well.The oil taken out was like treacle and when it was poured onto a shallow tray,you could put a finger in the oil and it would leave a depression for about a minute.Now that is a lot of particles in suspension !Looked similar to thick bitumen paint.

I am just trying to find any advantage in altering the timing chest cover and all the extra work needed to fit a filter on the feed side.
I have already established that an oil cooler,on an OIF bike, makes the oil too cool for road use and has a negative effect yet people will still fit one.
 
#13 · (Edited)
I used to rebuild large industrial high speed centrifugal compressors, these had a feed side oil filtration systems along with a very complex heating, cooling, prelube and postlube operation. The reason for a discharge side oil filter was to protect the plain bearings from any contamination which may come from the oil, the pump itself etc. Also the fact that is better to pump oil thru a filter than to try and use suction to get a flow.

The only reason for a discharge side oil filter on a Triumph is in my opinion to protect the rod bearings and keep the sludge trap clean. In my opinion it is better to have a filter on the discharge side rather than the suction side, but it is a pain to install it.

Having said all that its better to have a filter somewhere in the oil system than none at all, and the inlet type filters seem to work just fine too.
 
#15 ·
Regarding suction side filters, they can be very risky in that some types, or dry unprimed oil pumps can have poor suction. Obviously this can cause oil starvation.

Over the years at work I've seen techs forget a rag in the oil pan or timing cover & it ends up in the oil pump screen. I can tell you the oil pump cannot pull oil through those red rags you see in the workshop. Great damage is the results. Mercedes have not used oil pressure gauge or warning light in many years. The first sign is rattling from the timing chain tensioner, moments later the crank locks up.

So this suction restriction thought is what held me up on the Motao filter with it being on the suction side. Even though I ride my bike often even in rain, I show my bike sometimes so didn't want an external filter. I want to keep it visually stock as possible.

I know a few guys that had them to good results though.

So I did some tests to determine the effects of the filter. I got some surprises! Shockingly the factory strainer is quite restrictive. Does not flow cold oil freely at all. The Motao element paper has much more area than the screen. In cold oil flow tests they are very close to the same flowing 1 quart cold oil. With a full frame fill of oil, draining out the suction hose it takes a full 7 min. to flow only 1 qt. at 60f deg. Mobil1 v-twin 20-50 oil. Hot oil flows right out as you'd expect.

I T'd in a vacuum gauge to feed hose to pump & started motor. Screen & Motao filter have exactly the same vacuum. About 1" vacuum. So it doesn't take much suction to pull the oil through filter where gravity was very slow. Again oil 60f deg Mobil1 20-50.

Pinching off feed hose vacuum jumps almost instantly to 23". That would be enough to collapse the filter if clogged. I don't know if it could perforate the paper though. Of course a screen could clog as well. This goes for oil tank bikes as well as OIF. Looks like oil tank screen may have even less screen than OIF bikes. Very important to clean the screen.

I've seen OIF bike where owner never cleaned screen in frame. Was basically sucking the oil through the top of screen only. Sides were caked solid with sticky goo. Bike was working ok.

Don
 
#16 · (Edited)
I use Champion H101 filter for the Norton type oil filter housing.The pressure relief for these is a rubber piece that opens if the filter blocks.Very unlikely to block a filter if the filter is changed every 3000 miles.I have never seen a completely clogged filter on a maintained engine.
Really,you have to consider the modern car engine that has oil and filter changes at 24,000 miles or even The Triumph Rocket 111 with its very long oil and filter change mileage.The modern oil saves a lot of wear so much less particles need to be filtered out.These do not have any filters becoming clogged solid.Consider the amount of particles that a diesel engine collects in the filter yet the filter is changed at very high mileages.
Quality oil would always be the best solution to lubrication and i suspect that many good oils would be more effective,even without a filter,than a filtered engine using lower grade oil.
I ran my engine a very long time without a filter and there was very little wear to the bearings or bores and the sludge trap was half full at 40,000 miles.
Fitting a filter will obviously strain the oil a bit more so i do have them on the old bikes now but i would still say that there are thousands of these old engines doing very well without a filter with just more oil changes with quality oil.
It is also noted that the screen in the frame has a collection ring for keeping the heavier particles getting back into circulation.If this screen is not cleaned,it will build up a little black sludge so i clean mine every 3 years.Just a little bit to clean and not a big worry.
 
#17 · (Edited)
Quite agree with that, oil these day is far better than 40+ years ago, not sure why people have a problems with the suction side, and the term is a little misleading as it has pressure behind it just like the feed/pressure side.

If fitting a filter to the scavenge side your just causing a restriction to the return to the tank, and the pump will still pressurize slightly as the filter is a restriction,

As on the pick up side of the pump the pressure capabilities are as good if not better after the pump as it usually has a larger capacity then the feed side,
its just that there is far less restriction from a filter alone, than a filter in combination with forcing the oil through the small oil ways and bearings etc.
 
#19 ·
I was referring to putting a filter on the suction (inlet) side of the feed part of the oil pump, not in the scavenge or return line. Anything that adds resistance in flow by gravity to the pump is not really a good thing. Ive seen the OIF tank sump filters and people have good luck with them , it just goes against all my training to do that.
Putting a filter on the discharge side will not add resistance as long as the filter is not plugged. It is pressure that determines the flow. Having a plugged filter in either side of the system is a bad idea.
 
#27 ·
The way the pump works is not related to anybody's take on it. Get your hands on a Triumph oil pump and have a good look at it.

The feed bore has a hole in its side, open to the gravity supply from the oil tank. When the plunger is above that port and descending, some oil is pushed back out through the port. Once the plunger is down past the port, it forces oil through the ball valve, toward the pressure relief valve and the crankshaft.

You're right in that extra convolutions and voids between the pump and the crankshaft are, in principle, a bad thing.
 
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