Low oil pressure when hot........

[buggyfan]

Here goes
1993 1.6 carb citigolf
At start up idle oil pressure is at 4 bar and when you give it a rev it goes up to 6.5 bar and drops back to around 4 bar
As the engine is heating up the pressure gradually drops downto 1.5bar and the lifters start getting noisy and buzzer screams and oil light flashes.
So far Ive....
replace original Vw oilpump with a 2lt pump with the bigger gears from Autozone. Still losing pressure when hot
Replaced 20w50 oil with 10w40 oil. Still loose pressure
Replaced all 8 lifters with new Ina lifters from Gw. Still loose pressure and lifters become noisy.
As a last resort ive removed the crank and had it Mic'd at Engineer shop. They found it within spec still on big ends and mains.
Lastly I checked the intermediate shaft and found it has alot of play between the shaft and both bearings
Could this be where Im loosing oil pressure.
Can somebody confirm how tight is the shaft supposed to be in the beatings
Thanks Jaco

[n.gov3]

Intermediate shaft can definitely result in pressure loss......can't comment on how tight it should be however the best way is for the engineering shop to check clearances vs spec

[n.gov3]

Stick to the 20w50 oil as that is the correct spec.....10w40 will be thinner at normally operating temp

[buggyfan]

At the end of the day we replaced....
The oilpressure loss was partly due to a piece of gunk blocking the oilpassage from the block to the head but also the camshaft and camshaft bearing caps having too much clearance especially on nr4 and nr5 bearing cap.