Thoughts on 455 oil pressure drop?

I’m going to hook up a different pressure gauge today, not expecting any miracles though. After that I’ll drain the oil and have a look...

 

I bought a GS with similar low pressure. (5-10 idle 35 top end) Put thinner gasket on oil pump and a booster plate. Helped some but turned out the gauge was a liar.....

 

I once had a '94 Bonneville with the 3.8L V-6. I had always used the recommended weight Cam2 oil and Fram "standard" oil filters. I had just changed the oil and filter and everything seemed to be OK. Then on the way home from work the next day I gradually I lost almost all my oil pressure. I made it home and parked it until the weekend. I drained the oil to see if there was anything in it but it was clean. I put new oil in it anyway but it made no difference. Then on a lark I replaced the Fram oil filter with a cheapo Sears filter and BINGO - pressure was back to normal. Then I replaced the Sears filter with a Purolator and pressure was still good, and I never had another problem with oil pressure. I didn't do a post mortem on the Fram filter but apparently the element collapsed. Googling Fram filter problems at that time ( around 2004) confirmed my suspicion, and I discovered that I was not alone. This is the only time I ever had a problem with a Fram oil filter, but it was enough to turn me away from them for good, and with so many other choices I never bought another Fram oil filter since.

 

So far it doesn’t look good fellas.
First photo is upon startup; about 75psi, second after warming up about 10 min, then after about 15 minute drive at a stop sign; 5-10 psi (this pressure gauge goes to 300 so much less resolution). It maintains about 20psi at cruising speed 25-60 mph.

 

Next move is to drain oil and check it for sparkles also remove and check filter.

 

You mean the pressure is 20 psi @ 25 mph and also 20 psi @ 65 mph?

Also cut the filter open, if you dont have a filter slicer, buy one.

 

When you have the filter off, check the filter bypass valve in the filter adapter.
If yours is the original adapter, it may have a flat disc for the valve, sometimes they get cocked sideways, I've had it happen.
Later covers maybe from late 70's on up, have a conical valve, so it self centers.
OOOOOOR, the whole assembly may have popped out, had that happen too on a TA filter adapter, oil pressure maxed out @ 20 psi on the highway
I called TA to see if I could just re-stake it, Mike said yeah, so all is good

 

I have the TA timing cover and oil pump. Do I need to pull the whole pump or cover to check this?

 

Praying it’s something simple... I want to exhaust all simple things before pulling the engine and checking the pickup / mains.

 

Yes it maintains around 20-25 through all driving ranges. It goes down to 20 when I accelerate and goes up to 23-25 when I let off.[/QUOTE]

 

Just need to pull the filter off and look at the bypass valve to see if it's stuck open. It's right under the threaded nipple that the filter screws on to.

 

Knew I should've maybe used that one! Lol

 

Check valve looks good.

 

Watched a YouTube video and this guy uses tin snips to basically uncrimp the filter housing from the base. No metal shavings whatsoever ever. Last pic is inside the housing and it’s clean.
On the outside of the filter flaps was lodged this piece of nylon which looks like rocker retainer material?

Drained oil in a clean bucket; looks like some minor “sparkles” in it?

 

So in the bottom of the filter there is some very small particles.

 

No noises that I’ve noticed.
Guess I’ll change filter, pour in new oil and see what shakes out.
Both gauges have confirmed a lack of acceptable oil pressure increase with rpms. Possibly just excessive clearance in the bearings upon assembly without major damage yet?