I have a 98 Blazer 4.3L. When I start it up the oil pressure starts off at about 60psi and slowly drops down. Within about a half hour of driving it stays at 20 psi when I am pressing the gas, but when I brake and come to a complete stop it drops to 0psi. Just replace the intake gaskets (along with antifreeze and oil change) a week before. Was running 5w30 Valvoline oil for that week and just replaced it with 10w40 and it is still doing the same thing. Replaced the sending unit and also hooked up a mechanical gauge: still doing the same thing.
Any ideas would be greatly appreciated.

 

Probably going to have to replace the oil sump.


this is what happened to my 95 4x4, then it developed a rod knock.

and now I am finishing putting the new engine in...

 

If it showed the same pressures on a known good mechanical gauge and going to a heavier oil didn't change anything, then the pump is the likely problem, and not bearing clearances. I would get it repaired ASAP!

 

your pickup may need cleaning.

 

Any idea the time frame for fixing this and is it labor intensive? Wondering if I should do this on my own (with help) or take it to a shop.