1990 g20 oil pressure?
 

So what do these vans oil pressure run at around idle and in gear? I put a mech gauge on my by the distributor and it runs close to 40psi when warm at idle Is this an ok psi? It has a 5.7 and has 114k on the od. The cHilton book I have says 18psi at 2000 rpm

Idle rpm is what 600-800 and using the general rule of 10 PSI for every 1000K RPM 40 PSI at idle is very high. If you had not installed the mechanical gauge I would say the factory gauge was faulty.


That being said high oil pressure is not the worse problem to have as long as it is not causing oil leaks. Gives you time to track down the issue and I believe the oil pumps have a high pressure release valve maybe yours is stuck.