Oil pressure light

So recently I noticed that my oil pressure light flickers when starting up. It always goes alway once it’s running but when cranking it flickers real quick for a split second instead of just going off. Oil levels are fine, any ideas? But if I start it up after it was just running like at a gas station it goes off without flickering

 

mine has always done the same thing. No issues. Just the system building consistent pressure during the first few secs.

 

As long as the engine oil light does not come on while the engine is running, don't worry about it.

 

2017 gen 3 2.7L does exactly the same thing. posted a thread here about that awhile back. Sits over night, first starting in the am, oil light goes off when engine fires, then flashes for a split second back on, then off, stays off. If I just stop for an hour, start back up, goes out right after engine starts, no flicker. I work in the auto business and have started other 2.7's to see if they do it. Some don't do that at all, some oil lights linger a bit, some flicker WHILE cranking. Worried me when I first bought the truck. This is "drain back". If I google that, or "oil light", I just get endless posts about how to drain oil or reset maintenance lights lol. I think it is differences in oil pump tolerances and oil pressure switch reaction/dampening time. Sure would like to here from other 2.7L guys on this. If I put the recommended 6.2 quarts of oil in her, she does it most every day. If I put 6.5 quarts in her, almost never happens. Got this down to a science, bothers me lol. 40 years as a prof auto mechanic has me watching oil lights since the Taco oil light is "real time", as opposed to the Chevys which run a full gauge sweep after the engine starts, and don't even read actual pressure for a few seconds.

 

My '14 V6 does the same. I don't drive it that much, so it has ~36k on the odometer. But it only started doing it in the last 6 or 7 months. I've always used M1 5-30 and Toyota filters, since day one. Oil level is good, and I haven't heard any odd noises beyond the normal V6 ticks and tocks.

If I remember the oil route correctly, the pump draws from the pickup in the pan, sends oil through the pip inside the timing cover, into the filter housing, through the filter, downstream past the oil pressure sensor, and then onwards. Somewhere in that part of the circuit, the pump is losing it's prime or the filter is draining down. One bad anti-drainback valve I can understand. But the last 4 or 5 filters? I don't think so.

It's either in the pickup somewhere (loose, bad gasket), the filter housing (what would it be?), or the oil pressure sensor (it's a dumb switch, nothing more, supposedly clicks closed at ~4 psi).

I'm starting to think it's between the pickup and the filter housing. If I park on any sort of incline, nose up, it happens. If I park facing downhill, it doesn't happen. The oil pump also has a bypass on it, where if the pressure is too high, a check ball is pushed open and the pump dumps oil right back into the pan. It's spring-actuated, so it could be a lazy spring.

It's frustrating, since I'm gonna have to pull the pan and timing cover to figure it out and a truck of this age shouldn't need that.

 

Rather than pulling the pan, why not put a cheap mechanical gauge on it and see what the actual psi is?

 

I am convinced it is oil draining back out of the oil pump. Oil pumps on these trucks are two steel gears riding in a pocket inside an aluminum timing cover, driven by the crank. I have the 2.7L 4 banger, but I think the pumps are similar. There is no check valve or drain back valve in the engine, only in the filter on the 2.7L .I started seeing the flash and lingering oil light on first starts at about 5,000 miles. I always suspect the moving parts that wear in, not the stationary ones like the oil pickup, since it didn't happen until after break-in. Those 4.0L v6's are notorious for lingering oil lights, since the oil filter is upside down. On my 2.7L, I have tried several different oil filter manufacturers, but non seem to be any different that the Toyo factory filter. Also, sometimes the light seems to stay on longer than other times, can maybe attribute this to where the pump stops after the engine is shut down, like open or closed lobe. What bothers me is some trucks do it , and some don't, same engine, same year. I would not take my engine apart for this, probably would not see anything anyway. The dealers just give me the run around, to be honest, I would rather they not pull my engine apart. Think it is probably just differences in oil pump tolerance. Used to take an hour sitting off for that light to flash after start up, now will do it after sitting for about half an hour, so it is still loosening up I guess.
Some older 2.7L trucks rattle until that light goes out, some don't. Wish some of you Toyota guys would chime in here. Love the truck, worried about the lingering oil light.

 

Gotta buy one of those sandwich adapters, wait for it to get here, install it, make sure it won't leak. source an extra NPT plug (3 ports, ships with 1 plug last I checked). Other option is to pull the factory switch, but with my luck, I'll shear it off (they use loctite from the factory).

I'm ASSuming (I know, I know) that it's a mechanical fault. Maybe I should go through the lesser hassle and get a reading, first.

 

I dunno, but other than after an oil change, I'd never noticed the oil light lingering on the 1GR-FE V6 (this is my 2nd one, I had a '12 5AT that I swapped out for the '14 with the 6-speed). Have you confirmed via the FSM that you don't have an internal bypass valve on the oil pump? Most oil pumps these days do, so they won't pop the filter media with high pressure. But, anything is possible.

I guess I'll order one of those GlowShift sandwich adapters and see if I still have my manual oil pressure gauge from the days of working on AMC 258's.

ETA:

FINALLY got around to this. Picked up an inexpensive mechanical oil pressure gauge and a GlowShift sandwich adapter.

Pulled the oil filter, installed the adapter + gauge, topped off the oil, and started the truck.

With semi-warm oil:
Idle: 38-40 psi
3k RPM: 70-74 psi

With cold oil, after letting the truck sit overnight:
Idle: 50 psi
3k RPM: 80-82 psi (upper limit)

With truck warmed up:
Idle: 25 psi
3k RPM: 58-60 psi

During the cold start, I had to watch the gauge, so I'm not sure what the idiot light did. It did take 1-2 seconds for the gauge to start registering - took that long for the oil to get into the nylon tube and start moving the needle.

At least I know the oil pump works. For whatever reason, the feed between the oil pump pickup and the idiot light is bleeding down overnight. Not every night, but 75% of the time I'd wager.