98 bravada 4.3

bought it and replaced the intake, ive flushed the oil and changed the filter numerous times all the antifreeze is out of there. truck runs and drives great it just drops down to 20psi at idle. heres a short vid of the gauge

YouTube - VID 00020.3GP

i had a k5 in the past that would start up at 30 psi and eventually go down to zero and never had any problems with the truck too. just wondering if these gauges go haywire

edit... the heartbeat sound in the backround is the wipers

 

this is normal operation

 

20psi is more than adequate at idle. GM states a minimum of 8psi at idle and 10psi for every 1000RPM above idle up to 40-60psi depending on the engine.

My '74 K5 starts off at 30psi and drops to near zero at operating temperature, idling in gear. I have checked it with a manual gauge and it's showing 5psi at the block so chalk that up to an inaccurate factory mechanical gauge. The stock gauges on the newer trucks are more accurate than the ~40 year old tech in my '74!

 

yeah i had a 84 that did the same thing. ran at 30 but after about 30 minutes it went down to zero i just figured it was a bad gauge due to the truck running fine for years.

i was just kinda paranoid cause im gonna be selling this thing and dont want that to be a turn off. i changed the oil again and put some lucas in it and on the 5 mile journey home it seemed to hold 40 but it is alot colder out

 

my 99 blazer does it too.turn it on in the mornings at it well stay where it supposed to be,but then after awhile when i run it and im stopped at a light it well go down and then go back to where it was again when accelerating.

 

Is that for all GM engines?

My 4.3 is at about 45-50psi cold....then drops down to about 30-25psi at idle then when I went on a test drive it was around 40-45psi.

The 4.2 in our 03' Trailblazer is at 40psi@idle and around 45-50psi driving.

 

i ended up changing the oil and putting some of that lucas attitve in it. now it drops down to 25 at idle. so whatever im happy with it. i never really paid attention to my daily driver. its a 90 with 172,000 and it runs at 20 psi too

 

Glad to see that no one seems concerned with this. I just noticed it in mine for the first time. Drops to 25-30 at idle, then up to about 50 when driving. Was wondering if maybe I needed to change a gasket.

 

GM specifies minimum oil pressure should be:

OIL PRESSURE SPECIFICATIONS


1,000 RPM 42 kPa (6 psi)
2,000 RPM 125 kPa (18 psi)
4,000 RPM 166 kPa (24 psi) NOTE: Oil Pressure minimum at normal operating temperature.

Straight from GM GlobalConnect

 

mine does it too on my 99 blazer.dont know why but its been running farely well no problems.ive got 200,000 plus miles on it.