Old Ford CFL-1. Discontinued. Used it because only need for short Time before changing Oil. Using Purolator now.

  

Glad you found the problem being with the oil filter.  While I have had experience with oil filters failing, it typically results in a decrease or loss of oil pressure and not where the engine experiences an erratic or a swing in the oil pressure.  My three oil filters of choice are Motorcraft, Purolator, and Wix which does alleviate any oil filter issues on my end.  Like Paul, I too am curious as to what brand of oil filter you had the problem with.

Lorena, Texas (South of Waco)

What brand was the bad filter and what brand did yiu go with

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

All fixed  up. Changed the Filter and that has restored Pressure to 55-60 cold Idle which is very good pressure I think for a fresh Engine.

  

What brand filter are you using? A lot of defects out there now even the big names.

____________________________

I suspect I have a defective Filter. Cycling between full Flow and Bypass. I will change filter Monday. I have checked Tube and Seal. Not the Problem.

  

You are going to have to wait for TED to come on for the final word. He has seen more than most.

Be advised that if that seal is not installed correctly and/or is not a quality part (or the tube is bent), the pump will suck outside air leading to aeration and failing oil pressure.

____________________________

What is inside the Oil Pump besides Gears? Any check Valves or Similar I have never opened One up. When Engine Starts it shows 60 PSI and within 15 Seconds it drops. I am at a loss to understand what has happened?   I opened up relief Valve and spring looks fine, Haven't pulled the piece inside until I got a Magnet to pull it out. Really need some Suggestions. Thanks! Wondering if I have bad Oil Filter possibly? Would a bad Filter cause similar Symptoms?

  

Still got low to no Oil Pressure on Test Gauge. When I started this Engine initially it had 55-60 PSI Cold and ran consistently  with Steady Oil Pressure. Thursday the Gauge starting acting erratic. 60 40 0 20 etc. Replaced the Seal on pickup Tube Yesterday. . No difference. Tested Today with manual Gauge still showing same problem. There is Oil Flow because Heads are getting Oil  and the Idiot Light has not come on at all even with Low Gauge reading. What do I look at now? Oil Relief Valve on Pump? New Melling Pump. Not sure where to go now. Suggestion? Wondering if the Oil Pump itself is the problem?  Relief Valve maybe.? No external Leaks on Engine and it was fine until Thursday.

  

I took the inlet Pipe apart and re-installed it Today. Just satisfy my mind that is was not the Problem. Wasn't. Still doing it. Now I think it's just the Gauge that has gone south. I got a test Gauge from Amazon Today. Check it Sunday. The Idiot Light on Dash never came on at all which is why I am leaning towards bad Gauge. Stewart-Warner expensive Gauge. Mechanical. was working fine. Then it quit .Let U know outcome.