The Stovebolt Site Forums The Shop Area Engine Shop blocked oil filter canister outlet?

Hello. This is for a '51 Chevy 1/2 -ton 216 straight 6.

My truck has one of those bypass oil filters that bolts onto the intake manifold. The other day I removed the screw-top lid from the canister to get a part number off the filter element (I did lift out the filter element (unnecessarily) in the course of doing this). Today I started the truck and noticed oil leaking from the very top of the canister lid, where the lid's wing-nut type handle screws onto the threaded rod in the center of the canister. I assumed maybe I didn't properly seat the element, or didn't get the lid screwed on properly the other day. So I unscrewed the wingnut on top, and oil flowed profusely over the top of the canister (big mess), as if I had released built-up pressure.

My theory is that somehow the oil filter canister outlet is blocked, perhaps by grunge that I released from the element, or from bad reassembly, and the oil is not circulating, but being pressured up inside the canister. I would like to restart the truck and observe the oil pressure gauge but then I'd to wait again for pressure to subside. Maybe I'll do that anyway.

I think this should be fairly easy to figure out once I can open things up, but I wonder if anybody else has experienced this, and if so, what can you teach me?

Thanks!

The flow control hole is only 1/16" in diameter, and it can get plugged up, but it's also possible you were a little impatient and opened up the lid before the oil had a chance to drain down to the level of the hole (about halfway down the center standpipe). Let it sit a couple of hours after running the engine before opening the lid, and the oil level in the filter should be 2 or 3 inches below the top. The orfice is most commonly found at a level even with the inlet fitting hole in the side of the canister where it can be cleaned out by sticking a piece of thin wire through the hole. There is no check valve at the inlet fitting, so it would be unlikely that the canister could retain pressure for more than a few seconds after engine shutdown.
Jerry

It’s been a really long time (40+ years) since I messed with that type of filter. Don’t they have a o-ring or gasket under the lid to seal it? Maybe it is misaligned?🛠

There's usually a copper washer between the center nut and the lid, and a flat rubber gasket around the perimeter of the canister under the lid. Those are notorious for getting misaligned and leaking.
Jerry

Thanks guys. Yes, there is a rubber ring gasket, and it was finicky, not wanting to stay in place on top of the canister or inside the lid. Remember, my initial problem was a leaking from the center of the lid. Maybe I didn't get the copper washer back in place. I didn't even notice one, so that may be it. It's probably cool enough now that I'll open her up and take a look. I'll keep you posted.

Hotrod, very good point about no check valve in the inlet line, so there wouldn't be pressure with the engine not running, and oil would just flow back into the inlet, if I had given it enough time. Could you please elaborate on the 1/16" flow control hole that can get plugged. I don't get what you're referring to. The inlet and outlet hoses are flexible braided and maybe 3/8" O.D. The line that goes to the pressure gauge looks to be 1/8" O.D. and could be 1/16" I.D.

The standpipe in the center of the canister has a small hole that prevents the oil from flowing back to the crankcase too quickly. That would rob too much oil flow to the bearings, since a bypass filter is not in the main flow path between the oil pump and the engine. It bleeds off a small volume of oil, filters it, and returns it to the oil pan. You will need to pull the filter cartridge, clean the housing thoroughly because it will be about half full of oil when the cartridge is removed, and examine the standpipe closely with a bright light. The hole is hard to find, but it will always be there. A squeeze bulb turkey baster comes in handy for sucking up the residual oil, but don't borrow the one from the kitchen unless you have a death wish! Go to Wally World and buy one for the shop!
Jerry

Write "DJ's sludge siphon" on the side of the baster, with an indelible marker.

Well, I was about to report that I just wasted everybody's time, but I'm so amused by Jerry and Tim that it was worth it!

I won't go into what I just did out there (verifying open lines), but I have concluded that I had not screwed the canister lid on tightly enough. The gasket was in place, the washer is actually integrated into the spring in the lid, so can't be lost or omitted, and all I needed to do was tighten!

Now that I'm into that system, I will look for the hole that Jerry speaks of. Fascinating stuff.