FredTJ

I'm not sure that I would call those pressure "good".
Maybe if that is cold pressure, but certainly not hot operating
temperature pressures ....




Fred

Dirt Driver

Does anyone else think it could be possible that the anti-drainback valve in the oil filter may not be working?

Ezrider_92356

i would think possibly the oil filter drain back or the gasket on the pickup tube

the_supernerd

The anti drainback valve was my first guess, but I have changed the filter a few times and now I have a genuine Toyota filter. Can anyone think of a reason that the all the anti-drainback valves in the filters are not working? Could something like over-tightening the filters be causing the valves to not seal, maybe by warping the filter? I just remembered that this problem started happening right after an oil & filter change. The oil & filter has been changed since, but there might be something causing the anti-drainback valves to not work. Anyone have any thoughts on that?


I changed the gasket on the pickup tube when I cleaned it, so I would assume it is ok, although there is a chance a bolt came loose or something.

FredTJ: What are good pressures suppose to be?

vital22re

iTrader: (2)

well.. i'd pull the pump apart and check the gears. maybe its been damaged by a chunk of something. Also get a mechanical gauge to check your readings. maybe your sending unit is goin bad?

abecedarian

Hot idle oil pressure should be ~10 PSI or higher. Peak oil pressure should not exceed ~70 PSI. Anywhere in between those two is fine. Below 10 is a sign that the oil pump or bearings may be worn and above 70 is a sign the pressure relief valve isn't working properly. Seeing +50 PSI on a cold start isn't anything to worry about nor is 25 PSI with a warm start. My VW Scirocco would peak about 60 PSI on a cold start but that was with 20w50 oil and stayed together for over 300K miles, til I wrecked it.

Since you're hearing knocking on start up and it's a relatively new (even if cheaper) oil pump, I'd lean at the rod bearings may be getting old. Hard to check without pulling the oil pan though. Maybe try a heavier weight oil, maybe 10w40 or 15w40 and see if it continues. I run 20w50 in my 88 22re and 15w40 in my 91 22re. I live in southern California where it rarely gets below 32F and is usually above 70F. 20w50 can be used down to freezing without causing issue. If I run 10w30 or 10w40 in my 88, it gets rod knock but does not with 15w or 20w oil.

FredTJ

The Golden Rule for any gas engine that you are likely to own is (once the oil is up to operating temperature, which is 100*C {212*F}, and takes longer to get there than the engine coolant does ) is 10 psi / 1000 rpm.
So, at idle you should be no more than 10 psi.



Fred

the_supernerd

If the rod bearings were worn, wouldn't the oil pressure be low all the time, not just at start up? I will do as you suggested and try thicker oil on the next oil change. If nothing else, the thicker oil should at least help the pressure build quicker.

NicCantDecide

FredTJ: The entire time I've had the truck the oil pressure stuck around the middle of the gauge, a bit below the second line. I figured that was normal. Now it sits around the first line, maybe a bit past it.

I don't have a gauge with actual numbers on it, just the stock SR5 gauge cluster.

Dirt Driver

[QUOTE=NicCantDecide;51175844I don't have a gauge with actual numbers on it, just the stock SR5 gauge cluster.[/QUOTE]

Then you can't even be sure there is a problem. The stock gage is little more than a glorified idiot light. Get an inexpensive mechanical gage from the parts store and see what the actual pressure is.