Wondering why my oil pressure changes from day to day. some days at crusing speed it is about half way others it is about the first line. When it is lower the truck seems to have less power. and also it seems to run better on cold days? any ideas.
One more Q. Is the hose going from the charcoal can to the back of the motor to a green valve lookin thing inportant ? thanks

 

Welcome to Yotatech Trev...
THAT should the FIRST thing new users here will read. Next will be "search" and third will be "More info required" IE: Engine, model, year, any mods?, etc...

From my experience (91 V6 3.0), I can say that the oil pressure fluctuates with RPM. More learned people here have discussed this and the bottom line seems to be: As long as you are between the hash marks while running at speed, you're OK: At idle you may see it drop off, below the marks, but if it comes back up...good to go. If it never gets above the first line, you may have oil pump issues, which MAY indicate low oil levels, or a failing fuel pump. Hope that helps...
PS: ALL hoses going into any coloured looking things are important.

 

if your talking about it just having more pressure on colder days, thats cause the oil is thicker, as the engine warms up the pressure will drop off a little. as for the fluctuation.. being the same year as blair's, mine does the same thing.

oh, and welcome

2 things i wish mine had

 

This is the same thing i noticed with my 92. In fact my oil pressure was right low when i just got a lube change from toyota. I dropped the toyota oil and went back to castrol gtx high mileage. Even though the "high mileage" part may just be a gimmick it keeps my oil pressure perfectly in the middle at cruising rpm (2-2.5k) and about 3/4 at higher rpm before shifting when accelerating quickly (3-3.5k) always letting me tap into my 3.0 massive power reserve. all 3.0 jokes aside, i found that this combination of oil and toyota oil filter gave my 4runner the best performance and consistent oil pressure.

 

if you are really concerned about you oil pressure (like I was) buy youself a aftermarket mechanical oil pressure guage. It will put you mind at ease if you do in fact have good oil pressure. The Toyota oil pressure guage is crap in my opinion, they don't read correctly, and rarely read the pressure the same twice. My truck has almost 100 psi at cold startup high idle, and the stock guage never even gets into the high range. at 25psi warm idle, the guage hovers in the low part...

 

Yeah mine has always fluctuated. recently it started doing it worse. Nothing like going at freeway speeds and looking at the guage the first time seeing no oil pressure. Pretty sure it's just the guage though as the motor is still a baby and I know they replaced the oil pump on rebuild.

 

i've tried 3 guages and at least 3 sending units, and the guages all act the same. i have an idea how how to recalibrate the guage to reflect what's really going on, but it's pretty low on the prioity list. when i'm normally crusing along i generally have between 55-65 psi, and the stupid guage will be reading low..