heya peeps, does anyone here have an oil pressure gauge? I just got mine recently installed and when the car is at idle, the gauge fluctuates from 60-80 psi. when im driving the needle pretty much stays at 100 psi. my question is is this a normal reading or do you think that my gauge is off? the sender is mechanical so im not really sure if it is reading incorrectly maybe the car is just under high pressure all the time * shrugs* any input would be appreciated. oh yah, I have an echo but that shouldnt really be a problem cause its the same engine yadda yadda....

-Thanks

 

Seems very high to me, most modern engines idle somewhere around 20-30psi and raise with rpm, pretty sure every manufacturer has a different peak pressure, but I don't think its over 100 for any of them.

Assuming that you have a real capillary tube from block to gauge, I'd say that the tube is kinked somewhere, or that the pressure takeoff is not in the optimum spot (don't ask me where that spot is). If its mechanical in that theres an isolator (can't blow through it) between the gauge and the pressure takeoff, then most likely the isolator is one meant for a different gauge than the one they gave you.

Mike

 

I'm no toyota mechanic (only model T's for me) but that high pressure sounds like the result of excellent tolerance control.

See, an oil pump has only so much capacity to deliver x volume of oil at xx psi. If the pump clearnces, or the engine bearing clearances are the least bit loose it is very unlikely you'd see more than a fraction of your present high pressures.

Yes- at idle the figure will be lower and at high rpms teh pressure will be higher becasue the pump speed varies directly with the engine rpms but the leakdown rate does not vary much with rpm. But to have numbers so high as you documented impresses me.

While such high pressure is not actually -needed-, big pressures do no harm- the limiting factor being the burst strength of the oil filter (no problem there).

The high pressure ensures super ample oil supply to the bearings under all conditions.

Do I trust your mechanical gauge's accuracy. Yes, actually I do, plus or minus 20% which is likely the design tolerance for a low cost guage.

If your pressures were higher than the manufacturer wanted, the pressure relief valve will open at design limit. Which, I intuit is just about 100psi.

Good job, Toyota. I wonder if USA made big three engines develop such high pressures? (But understand 20PSI would actually serve just as well, really)

Also, everyone should know that oil pressure varies greatly with oil viscosity. And viscosity changes downward in time and with higher temperatures. If you never, ever change oil eventually the viscosity -increases- to the brink of becoming a gel. But of course, before that quite happens your oil if low goes high again (less leak-down) and then the engine seizes when oil circulation falls below a critical minimum.


The actual theory of oil lubrication is very interesting to gear minded folks. Would an essay on this topic be of any interest to any readers here? Do you ever wonder just -how- oil lubricates a spinning crankshaft? Well- as a teaser I can say this much: crank bearings don't survive because an oil is oily, per se. That's not the mechanism of how shaft bearings work. Under certain contditions you don't need oil on a shaft at all. Some shafts spin at 500,000 rpm (see your dentist ). A dentist drill today does not spin its shaft in ball bearings. No, it's a plain bushing. And instead of oil the "lubricant" of the shaft is compressed air. The shaft spins without contact on the bearing and with zero wear. The same effect obtains with oil in your crankshaft bearings: practically zero wear!

but i am getting windy, sorry. I have this weakness to learn and share "how things work" because there is much mystery and natural wonder in these everyday things. But who else is interested? Anyone? I wouldn't want to come across as a bore or know it all. And I don't know it all, beleive me! But not sure about the point just prior ha ha.

 

thank you for your input. I dont know if this will really make a difference of not, but I only use the trd oil filter in my car to allow maximum flow of oil to the parts. I also only use mobil 1 full synthetic 5W30 oil and change religiously sometimes sooner because my car is my child

 

60 to 80 psi at idle is very very high (assuming the car is warmed up). The xB service manual states that normal oil pressure at idle is 4.3 psi or 0.3 kg/cm2. At 3000 rpm pressure is supposed to be 22 to 80 psi or 1.5 to 5.6 kg/cm2. One thing to keep in mind is that when you first start your car oil pressure will be very high at idle because the oil is cool. Once the car has warmed up the oil will "thin" and the pressure (particularly at idle) will drop significantly. I have an electronic oil pressure gauge that reads in kg/cm2. Once the car has warmed up, my gauge typically reads 0.5 to 1 kg/cm2 at idle and 5 kg/cm2 at 3000 rpm. When I first start my car in the the am the pressure reading can be 5 kg/cm2 at idle, but will read warmed pressure in a minute or two. I also have a oil temperature gauge that makes understanding the oil pressure easier. For example, I'm not worried if my pressure is high if I look and see that my oil temp is very cool at start.

If you drive the car for a while and still are getting 60 to 80 psi at idle, then there is probably a problem with the gauge or sender.