Oil Filter Canister 48 Cub

[Plywud]

I've had this girl for about a year now, and am finially caught up with the big projects, so wanted to change the oil. Gasket was leaking, so I removed the pan, and the oil at the bottom after draining was pretty dark and thick. The oil filter canister had some sludh dripping out but no oil, filter was dry and clean. The pick up tube screen had some what looks like carbon build up on it, not metal, but pretty hard. The oil pressure gage has always shown around 25 PSI or more, engine is not making the traditional clicking nosies from dry lifters, and there are no metal shavings in the oil itself. Have looked at the oil system model diagram, is it possible for the oil to bypass the filter canister and still lube the piston rings and bearings without going through the filter canister? Read the procedure for priming the pump, which I will do after I get the pan back on and oil installed.

RJ

[Matt Kirsch]

If I am not mistaken only a portion of the oil that circulates goes through the filter. This is typical of tractor engines at the time.

[indy61]

If you're talking about the tube that runs down from the oil filter canister it's common to see them clogged with sludge. Probably from earlier years using non-detergent oil.

[Eugene]

The oil filter is at the end of the oil pressure system. Your 25 psi on the gauge is the oil pressure throughout the system.

[Bill V in Md]

Make sure you clean and flush (With kerosene) the oil filter case and drain tube with drain plug removed. If you don’t want Kerosene and sludge to wash into crankcase and oil sump, just replace the Oil filter bolt without the cover, before flushing.

[Gary S.]

"engine is not making the traditional clicking nosies from dry lifters" C60 engines have mechanical lifters no oil in them like hydraulic ones

[Glen]

Hi,
The original oil pressure gauge is on the oil filter housing, if there was no oil pumped into the oil filter area, the oil gauge would show no pressure.

To check it so you can see if oil is being pumped there, you could leave the top off the oil filter, and briefly run the starter. Oil should squirt out of the small hole near the top of the housing, where you prime the oil pump, if needed.
The oil may squirt out and make a mess, you could hold a rag there while the starter is running.
Wear your safety goggles also. Be sure to leave the ignition Off.

Like was said above, Cubs don't have hydraulic valve lifters, the valve lifters sound about the same with no oil pressure.
When there is no oil pressure, and you run the engine, there is soon knocking sounds from the crankshaft bearings, which are low in the engine.
The crankshaft bearings are soon ruined running the engine with no oil pressure.

The oil filter housing drain pipe, under the starter, can get plugged with goop over time, if nobody drains it.
Remove the cap, and if the pipe is plugged, let it sit with the cap off, and the goop may slowly move down and come out. I remember one doing that.

[Rick Spivey]

It sounds from your description as if the center bolt/tube in the oil filter is clogged solid. The oil would circulate through the engine, since the filter is not in the primary path of the oil. It sort of sits to the side, and oil is filtered somewhat voluntarily as opposed to force filtered. There is a name for this setup but I forget it right now. Clean the bolt well, as well as the filter housing, and start over with a fresh filter. The engine likely was getting properly lubricated, but with somewhat dirtier oil.

[Urbish]

There is a name for this setup but I forget it right now.

I believe the term is 'Bypass Filtration'. My Willys CJ3B has a similar setup.

[Gary Dotson]

It’s a partial flow filter system. A portion of the oil, from the oil pump, passes into the filter cavity, by way of the passage at the top of the filter opening. It then passes through the filter media to an orifice in the filter bolt, where it drains directly back to the crankcase. It’s very common to find the filter housing empty, when the cover is removed, it’s called gravity. Since the gauge is ported directly into the filter housing, if your gauge shows pressure, oil is being pumped through the filter. What you have is completely normal.

[staninlowerAL]

From an old post in 2014, I can't remember which "Rick" was the poster......... The diagram is probably from one of the manuals. Stan
Oil pump & flow through engine:
Does anyone know where the picture is of the oil flow through the cub engine? I've searched and looked and can't find it. It's in one of the manuals. My point to the whole topic is to show how the flow "T's" off to fill the oil filter housing. If the filter or passage in the long hold down bolt becomes plugged, no filtering is done to the oil. All the oil will just pass through the galleries. This should prove why it's important to maintain clean oil and filter. Rick

Turns out the Cub engine sucks oil up through the pick-up tube, into the oil pump, and then into the main oil gallery that feeds the tappets, cam, and crank bearings. Off this main gallery is a port that travels across to the oil filter assembly, filling up around the outside of the element, through the element, and then back down into the oil pan. Once the filter becomes plugged, NO FILTERING is done.

[Bill V in Md]

That flow diagram is in the Blue Ribbon Service Manual GSS-1013 “Engine Lubrication Manual”.