leseid

Okay, let me try to state my question as clearly as I can.

First, of course your running pressure drops as the engine warms up. And of course differing viscosities will result in different running pressures. We're on the same page there.

But what seems unique to me about my V6s running pressure is the rate at which it moves from 1/2-2/3 or so on the gauge to down around the first hash mark with the engine rpms staying constant. It is the fastest drop I have ever seen, and it does so consistently.

Now, it cannot be a viscosity issue per se because I read too many posts from too many people worried about this running all manner of dino, synthetic, 10W-30, 10W-40, etc. In other words, if the issue were due to a specific viscosity being a bad match, only people running that viscosity would have the issue.

Lastly, I doubt it is a huge issue, though Ardent's reiteration that there might not be an idiot light on my gauge does concern me. However, as Jason points out it would be foolhardy to trust the gauge without getting a real mechanical read on it first.

Basically, it seems to me that the pressure drops faster than temperature rise in the oil might explain and I am just wondering aloud if the pressure regulator valve might somehow play a part. I fully understand it just might be a quirk of the Toy gauge in this rig that I am not used to, but I kind of doubt it.

eddieleephd

Okay after reviewing the FSM and your restated issue I would say that your issue could be in part due to the relief valve! at least the spring that pushes on it!
This is a logical problem with this pressure issue. Not only where it is located but as well
how you in particular describe the drop in pressure!

On these terms I definitely suggest replacing the spring and valve along with the oil seal since you wouldn't want to go back just for that and they don't cost so much!

So you would definitely be right in that thought!

I am still on the side of an oil gauge and maybe at a future point experimenting with the viscosities if this does not cure it completely!

This may be every body elses issue as well I mean we all know that stock suspension is a weak link why wouldn't other springs be as well?

FSM
http://www.ncttora.com/fsm/1990-1995...es/repair.html

leseid

Yeah, it's a weird one. I just want to make sure I am not letting it mask a crankshaft bearing failure or pump clogging or anything—the quick drop is just too much like a bearing failure symptom for my comfort. If it did not show up so often in the forums here I would be more concerned than I am.
At any rate, I am 800 miles from my shop and will have plenty of highway miles to see what is going on on the way home. When I get back to the wrenches I might swap out the pump and pressure valve just for experimental sake and report the results.

eddieleephd

Heck man I travel too much to have a shop! just enough wrenches for most stuff but roofs to work under are hard to find some times so I am constantly maintaining so I hopefully dont need one! by the way where are you 800mi from home I grew up in so. and central Cali.

If you are close to San Diego I may have a friend that is available with some wrenches!

leseid

Been there done that: once rebuilt a Subaru in the eastern Oregon woods with a Leatherman tool, borrowed sockets, and a come-a-long. Too beautiful where I live now waste much time looking at the dashboard on the way to somewhere else.

Ardent

Not on a Second gen 4Runner! It was the e-brake light i forgot...

mechkyle

I came to this forum post when I googled low oil psi and was surprised to see the same conditions. I have tried lucas and it works but run synth 1030 with half bottle lucas so the oil isn't too thick to get to all parts of motor . Haven't done oil psi check yet. Even with straight synth psi (as per cluster gague) drops as oil thins out but seems less than natural oil.

nunes5344

same problem. it seems good at cold start but when it warms up the oil pressure drops to the 1/4 mark... if its like this with all your runners then is it still considered a problem? -93 toyoda 4runner "white trash"

Kenny Gilfilen

I just googled my tacoma problem and came here. I took my truck, with 270K miles, in to change the valva cover gaskets; it was leaking. The truck has been a champ for all 270K, but when i left the shop the oil light came on when it warmed slightly, after 2 miles or so. I took it back and they checked the pressure and found that it was low enough to turn the light on.

the pattern seems very close to what others have described. 1. Can anyone think of anything in tha gasket replacement job that might cause this? 2. Did the guy with the oil pressure regulator question have any luck with that repair? 3. I am thinking abiut putting in oil that is thicker than 5w-30 that is suggested, any issues with that?

Co_94_PU

iTrader: (-1)

oil pressure is a function of clearences and supply volume, both will fade with time it's a simple fact..

You'll need drop the oil pan, inspect then remove the pickup tube and clean it if needed. It's a low cost repair, gasket goo and time. You'll find it very hard to prove the mechanic is at fault no matter what you find if anything. If the pickup tube screen is clear and not restricted you only have two options, replace the oil pump which will buy you some time, or rebuild the engine and tighten up the clearences.

As a stop gap you can use a heavier oil but you'll still need to use good practice. That is let the engine come to operating temperature before you stress it by driving.. Learn to identify the spot on your ignition where the starter is active and the ignition contact is open, it's a very fine line but with practice you can crank the engine over indefinitely and it not fire off which will prime the oil system..


QA
Yeah they could have scraped gunk into it or diluted the oil with solvents, but you'll not be able to prove them at fault unless you find the employee name badge lodged in the screen.