oil pressure drop help

[bdog9seclx]

heres the thing gotta 2000 with a 306 lately here the oil pressure when it first cranks is about 65 psi as the car warms up the psi drops slowly like in relation to the temp...when it get to 160 deg the oil pressure is at about 15-25 psi i have autometer gauges.... if it gets any hotter than 160 it drops to 10 psi+ but when the rpms go up it tends to rise to about 30-40 psi as i drive...yesterday in traffic temp got to almost 200 and oil pressure was almost zero?!?!?!?!? i dunno if heat fluctuation might also be a symptom of something....what in the world could be up oil level has always fluctuated with rpms tho...but never got lower than 30+...
someone said it could be a spun bearing but i dunno please help
does this sound like a sending unit issue...oil pump issue ....bearing issue or pick up issue...or something completely diff?

thanks all

 

[ExplodingGopher]

electric gauge right? before assuming anything is wrong with your car, eliminate the possibilty of the sending unit or the gauge being bad.

 

[bsedwebt70-5.0]

Sorry - sounds like crank bearings..... Mine did exactly that 2 months ago - bearings were gone - and the crank was wiped too because it went too long -- my other car did the same thing too but it was caught in time and all it needed was bearings and not a total rebuild

 

[vristang]

What is your oil viscosity? Did this start to happen after an oil change?

 

[bdog9seclx]

no it didnt happen after any oil change...so u think its the crank bearings or cam bearings and how can i tell if my crank is bad? Also y does pressure stay normal until around 170 degrees? The guage uses the plastic tube from the sending unit...
Supposedly its a fresh motor what coulda caused it and how hard is it to change the bearings?
thks for tha help

 

[the98stang]

I wouldn't jump to any harsh conclusions just yet. Check the Autometer gauge to make sure it's working properly. If it read 0 psi at one point, I think you would hear piston slap or rod knock by now. Check the sending unit first.

 

[DMAN302]

Get a new sending unit..if the situation looks the same, get out some good wrenches and go shopping for a new oil pump.

 

[dvs bullet]

take out the sending unit and check it with a mechanical gauge before youget to crazy

 

[vristang]

no it didnt happen after any oil change...so u think its the crank bearings or cam bearings and how can i tell if my crank is bad? Also y does pressure stay normal until around 170 degrees? The guage uses the plastic tube from the sending unit...
Supposedly its a fresh motor what coulda caused it and how hard is it to change the bearings?
thks for tha help

Oil will thin out when it gets hotter, that is why I asked about your viscosity selection. It is perfectly normal for the oil pressure to be lower once you hit operating temps. But the pressure should always be above ~20psi. I really hope you are not running a straight weight like, SAE 30.

Someone else made the excellent point that without oil pressure, you will hear atleast some valve train noise, depending on how long the pressure is at 0psi. If you aren't hearing any noise then it is definately time to look into a real gauge.

jason

 

[jerry beach]

He is running a manual guage, since he said it has plastic tubing. It has no sending unit at all. You could verify it with another guage and new plastic line.

The engine should be making noise if its really got no oil pressure at idle.

 

[bdog9seclx]

What weight oil shoukd i be runnin yea think?
yea i have auto meter guage in it i think guage is working accuratly....there is a def relation to temp

 

[bsedwebt70-5.0]

my last car was making no noise when the guage showed 0lbs at hot idle - I put a mechanical guage on it and it showed 8lbs at hot idle - no noises - drove fine and so forth - low pressure scared me so I pulled the pan and pulled the bearing caps -- they were way toasted at 112k miles - the crank had really deep grooves in the journals and had a bend to it - the machine shop refused to work with it - I had to get a new crank from Motorsport for $250 -- ALSO the balancer was spun and wobbly - may have been the reason the crank was sooooo bad - I do not know how long the balancer was spun for as I had just purchased the car -- live and learn...