Engine: Canister Oil Filter Question

[Robert Crandall]

I am cleaning the add on oil filter that is on my 1949 2R5 as part of my scheme to some day drive it again. I cannot figure out its operation, so I will ask the experts. When I put the bolt in the top of the threaded center pipe and blow air into the bottom fitting, air comes out only below the spacer at the bottom of the pipe. The drain back to the oil filler tube is at the top (left in the picture). My feeble brain sees the oil coming out the bottom of the pipe then going back to the motor at the top without entering the filter. Obviously I am missing something, but I do not see how oil will get inside the filter. How does this filter work? What am I not seeing?

Thanks.

[Neal in NM]

Pressurized oil should enter the housing from the hole on the side, pass through the oil filter to the center then drain back to the sump from the bottom of the housing to the oil fill tube.

[Robert Crandall]

Thanks. Yes, I do have the routing backwards above. The pressurized line does enter at the side of the canister toward the top. The drain is at the bottom. I will look again, but I do not see a way for oil to get into the center pipe above the spacer at the bottom of the canister which would mean that oil returns to the motor without entering the filter. This makes no sense, so I am looking for what I do not see. The canister had sludge at the bottom before I cleaned it, so something kept that out of the motor.

[jclary]

Thanks. Yes, I do have the routing backwards above. The pressurized line does enter at the side of the canister toward the top. The drain is at the bottom. I will look again, but I do not see a way for oil to get into the center pipe above the spacer at the bottom of the canister which would mean that oil returns to the motor without entering the filter. This makes no sense, so I am looking for what I do not see. The canister had sludge at the bottom before I cleaned it, so something kept that out of the motor.

If you examine that center standpipe closely, you should see that there is a tiny hole in the side of it, not at the very bottom. There is where the oil circulates. The filter element hugs that standpipe by way of a tight gasket. When the element is installed, the center pipe is isolated from the exterior fittings. Any oil that passes from the outside (of the inside) to the center...gets filtered. Put a new filter element in, install a new lid gasket, and enjoy. Us poor ol' country boys have been doing it for years. on tractors and Studebakers.

[Robert Crandall]

Found it, so I now feel educated, and I know how the filter works. I am not quick, but I do sometimes eventually catch on to what I am looking at. I plugged the bottom fitting then filled the tube with oil, and two holes near the top of the tube became obvious.



Thanks for the direction.

[BRUCESTUDE]

This is what's known as a "partial flow" filter, meaning only a small portion of the oil gets filtered while the engine is running. Over a period of time most of the dirt passes thru here and gets trapped. Stude went to a "full flow" filter in 1962, this is basically the same set up which is found on modern engines.

[Robert Crandall]

Thanks. I am straight on partial flow filter operation now, and I am glad someone put one on my motor long ago. Now I wonder why sludge was outside of the filter. Is sludging caused by particles smaller than the filter will trap? Or, does sludging have a different cause?

[jclary]

Just a guess here, but these filters can be plumbed up in either direction. I have one on my 51 Land Cruiser that was put on from the factory. Recently, when I changed the filter, I took the time to remove the assembly and thoroughly clean it. I had never had the complete canister off since I got the car (1988). There was a good deal of heavy liquid (not quite sludge) in the lower half. I think the direction of oil flow is from the outside-in. That is probably why the stand pipe has those holes higher up. That way, heavier particles are trapped in the lower half of the filter canister. Some filters offer a drain valve on the bottom. Most of our Studebaker filters do not. I wish they did.

If you notice, lots of canister filters use gravity as a filtering aid, by orienting them to trap heavier particles as they flow through the filter cavity. Hydraulic, air, water traps, etc. A good example is the glass filter bowls on our fuel pumps. There are even "stand-alone" glass bowl filters for our fuel lines. I have a period correct Carter on one of my vehicles.

[Neal in NM]

I don't believe it would be wise to hook up this filter backwards. The element is designed to filter from the outside to the inside, it actually has more surface area on the outside. My other concern would be, trying to get the element off. If dirty oil was run from the inside out, the "dirt" would accumulate around the center post and would not allow the filter to slide off. Neal

[jclary]

I don't believe it would be wise to hook up this filter backwards. The element is designed to filter from the outside to the inside, it actually has more surface area on the outside. My other concern would be, trying to get the element off. If dirty oil was run from the inside out, the "dirt" would accumulate around the center post and would not allow the filter to slide off. Neal

You are correct...old mechanic breath (term of endearment)...just because you can...don't mean you should. Also, since the circulation holes are designed so that the filter does not empty through the bottom, it allows for heavy particulates to remain trapped in the lower part of the cavity.

"Back in the day," these filters were not exactly user friendly to the service guys, but effective in their simplicity. I suppose if you were gonna charge a whopping two bucks for an oil change, getting good 'n dirty, was a way of demonstrating you'd earned your money.

[Dwain G.]

Any shop that did oil changes used to have at least one 'sludge pump' on hand. This is a tool similar to a hand operated grease gun, but with a plastic hose on the end instead of a grease fitting. Used for sucking up the gunk in the bottom of the filter can.