TR2/3/3A oil pressure drop

[TFB]

Yesterday noticed oil pressure at 20psi when at hot idle when before consistently 50-70psi.
Rpm increase to 2k=40psi ,2500 =50psi
So a rather sudden drop of about 25psi across the range.
Changed oil to usuall 20-50,cold idle25,usually 70psi
So somethingchanged,New rod bearings were installed with new liners and pistons1600 miles ago.
no niose and motor runs great.
I am going to pull pan and check rod bearings but wondering what else to check.
The gauge moves smoothly from20-50 when rpm increased but have not checked to another gauge at the block, but will before pan drop.
Could the relief valve be bypassing?
I have spin on filter conversion so I dont thik its a filter/housing issue.
If rods bearings look ok I will pull the pump to inspect.
Any thoughts appreciated.
Tom

 

[Hamish Racing]

Think I’d be cleaning the pressure relief valve and its seat. But the pressures aren’t worrying ~ but I get the change is !
Cold idle at 70psi is too high in my mind.

 

[CJD]

+1...70psi at idle is not normal, unless your idle is above 1000rpm.

I would not sweat rod or crank bearings. There is no failure mode that would cause the pressure to change that fast due to bearing wear. I agree the most likely cause would be a stuck pressure regulator. It can be checked and adjusted fairly easily without removing the entire filter head. Pull the ball out with a magnet to make sure it is round and not stuck, then set it for about 70 psi at 2500rpm.

 

[TFB]

Thanks for fast replies.
I just pulled the relief valve.The ball is inside the spring housing and came out with the spring and ball housing.
Seat and spring look good,no gunk,probably not my issue.
My main concern was the sudden psi drop.
The motor has 23k or so when I put new liners into resolve liner protusion issues and head coolant leak.
Rod bearings looked good with minimal wear but I put new bearings in while it was all apart.
This was after Head gasket had first blown at about 95mph,water and huge clouds everywhere.Luckily no water ever in oil.
When changing liners and pistons I noticed cylinder at blow ourt#4,had ring land broken and ring cracked,This about a thousand miles after the big blowout where I only changed just a head gasket that didn't work,but I put that 1k with the broken piston and ring,with no noise,smoke or scoring on skirt or liner.
I mention this because I wished I had checked the rod for straightness but with no sings of excessive wear on the shells or journals I just put everything back together.
Still need to check with another gauge at feed before flex line and if that checks out drop the pan,or just drive it and see what happens.
Thanks again
Tom