I've just installed my 22R-e after a complete overhaul w/ pistons, bearings, oil pump etc. It started up directly and ran amazingly! After what I've been through with my last engine I didn't think a toyota could run that great...but
the gauge for the oil pressure barely moves. When I rev the engine to 4000 rpm the marker barely reaches the first notch on the gauge. If I recall correctly my last engine always ran with the gauge pointing at the middle, alongside with the temp gauge. I have switched the entire cluster to one from a 1990 model and my oil pressure sending unit come from my stock 1993 engine. Could that be it?
How much clearance do your rod and main bearings have?
Are all of the threaded plugs installed in the block and are they tight? They could be leaking.
>>>*Yes, the pesky oil galley plugs. Machine shops often remove those to assure the oil galleys are cleansed.
*Having done this, they can be forgotten. The one in the rear you will know about if it is missing from the pool of oil on the floor.
The one under the oil pan will give you zero oil pressure if it is missing.
The one in the front however, will give just a tiny trace of pressure, best to check that.
The oiling system on these engines is amazing. The front mounted oil pump drives right off the crankshaft and if there is any oil at all the shaft will lube. I will say that I have never seen a "defective" oil pump, the design will deliver oil when the pump is all but worn out!
If idle pressure is very low, then suspect a bypass valve stuck wide open, but even if this is the case the pressure will recover at speed, just slower than normal.
If this all checks, then next is bearing clearences. The rod bearings can be as loose as standard bearings on a .010" undersize journal and still make 30#, that simply sounds like the valves need adjusted. We had one gentleman that didn't like the "cheap" .010" Rock bearings we supplied, so he went and bought a set of Standard Clevites...*LOL**..
Drove the thing for a month that way, finally pulled it out and brought it to us. We had a nice laugh at his expense, and installed a correct set, it wasn't hurt a bit.
The mains, on the other hand, will let oil pressure drop rapidly after .004" clearence. Anything between .0008" to .003" will run perfectly normally.
Other than a plugged oil galley, (dirt, silicone, etc) that is it, or a main line out of round which is a bit rare on these. That can happen, almost always drawing inwards at the parting line. This will give vertical excess clearence assuming she doesn't just lock up when snugging the main cap bolts. Even when we see this, she will make fair pressure, just not sweet. The cause of course is the housing draws the bearing shell into a vertical elipse. The only solution then is to dress the main line to round again.
The gauge is one of Toyota's weak links. I am not sure why, but the 22R and RE is the one engine that we always check the gauge first, about half of them read wrong. Sometimes way high and sometimes way low.
*Maybe that is why so many just use a light?..If the gauge checks and pressure is still low, suspect main bearing clearences.
One other thing. If she is nice and wet up top, lots of oil up there, don't worry about it, just drive it. If it gets to there, it is getting to everyplace else too........*EB