I got a slow leak out of the front seal, filter and possibly the oil pump in my 85 2.4L and I'm debating if I want to fix them or run it. Planning on hooking up a pressure tester, but I'm curious what I can learn from the oil pressure gauge on the dash. Do the increments on the gauge correlate to any approximate PSI? Mine usually runs just over the 1/4 mark at idle, and climbs to just over 1/2 way driving around. I'm not sure what the 'normal' range is.

 

My sources say the 22R & 22RE should make about 45 to 50 PSI of oil pressure at 2500 RPM. Given that and your description of how yours is operating, I would assume the gauge is basically "ranged" for 100 PSI. Running just over the 1/4 mark at idle & full operating temp should be around 20 to 25 PSI, which sounds right to me.

Why would your oil filter be leaking? Also, your front crank seal is in the oil pump housing itself and has an O-Ring seal behind the pump where it mounts to the Timing Cover:


Toyota 20R/22R/22RE Oil Pump

You would have to remove the crank pulley to replace the seal and/or O-Ring, which can be a chore. If it were me & depending on mileage/conditions, if I had to go that far to replace the crank seal and/or O-Ring, I'd probably just tear down the whole front of the engine and do the Water Pump and Timing Chain as well.

 

Yeah that's the thing, I'm already planning on the water pump but if the oil pressure is low I'll probably spring to get the whole front sealed back up. I've counted one leak at the front main, possibly the oil pump O ring, the oil filter (worn seal I believe) and a slight leak at the timing chain cover around the heater pipe on the drivers side. The leaks are slow enough that the oil level has stayed up for the two months that I've owned it even after driving across state a few times.

Another factor I'm considering is the timing chain and guide. The engine was manufactured in 84 so it could have either the single or double roller if I'm not mistaken. And this is a remanufactured engine so I'm not sure if they put new guide and chain in there or what. Taking off the valve cover to check the timing chain stuff and then confirming oil pressure seems like it will probably be the best approach from here.

washed the engine off to check for leaks. looks like the front main.

looks like the back of the oil pump leaks a bit too. coolant drip is from the water pump.

another leak that looks to be coming off of the back of the timing chain. sometimes it drips down to the block.

 

Unless you are leaking a lot of oil (which you aren't), then your oil pressure isn't effected by your leaks.

These oil pressure gauges are accurate, but not precise. What I mean by this is these oil pressure gauges accurately tell you if you are operating in the "safe" range, but are not precise enough to give you true "psi" readings. It doesn't hurt to check your oil pressure with a manual gauge, just for the piece of mind.

Here is what my owner's manual shows as the "Normal" oil pressure ranges for both Idling, and normal driving:

 

old87yota has a point. The leaks are small but you're likely to have good oil pressure if the pump can make enough to squeeze a few drops thru those small leaks, so probably no worries on the pressure. Taking the valve cover off to get a look at the timing chain is a great idea, and then you'll know if it's a single or double chain.

If you do decide to replace the timing set just make sure you get a set with the steel backed guides, as they last longer. The all-plastic guides have a history of breaking within 50K miles.

 

Using an OEM sensor (after market read very low), my 86 truck 22re SR5 will idle right at the 1/4 mark and at a constant interstate speed in 5th gear at 2800 RPMs at 65-70 mph above the 1/2 mark. It's been reading like that since the day I bought it new, so yours reads similar to mine.

 

If it were me, and it's not, I'd keep a sharp eye on the oil leak on the front main seal. I've had 3 seals have "catastrophic" failures so far. Be driving along, and SPLOOSH! Oil everywhere, except IN the engine.
Other than re-installing the harmonic balancer, replacing the oil pump seal is actually pretty easy. It just comes out with a same-sized socket on it, and a rubber mallet. OR a hydraulic press, if you have access to one. Installation is about the same. The bolt that holds the harmonic balancer on can be tightened to specified torque by blocking the rear wheels, putting it in 4th or 5th gear, and setting the parking break.
While the oil pump is off, check the crank shaft. The crank can develop a groove where the seal rides on it. They make seals that are slightly offset, so that they ride in a different place on the crank. That way, you get a better seal.
The oil pump seal itself is a bit of a pita to get on. It insists on falling out of the groove in the oil pump shell it rides in when you try to put the oil pump into place. Darn frustrating. My mechanic friends told me to put a small dab of thick grease in various place around the the groove on the oil pump, especially the corners, and then put the seal in the groove. The grease will hold the seal in place while installing it, without interfering with the seal between the pump and the front chain cover.
This method works real well to get the valve cover gasket to stay in the groove while lowering the cover into place on the engine. I do it every time, and it keeps me from fighting the seal to keep it in place.

While you have the valve cover off to check the timing chain, check that it's seals are still in good shape.
The PCV valve's grommet, too. It get's brittle, and can come apart in pieces when you try to remove the PCV valve to either verify it's operation, or just replace it. With the valve cover off, you don't have to worry about the little chunks of grommet falling down into the engine. If you replace the PCV valve, make sure you use an OEM valve, not some aftermarket generic cheapie. It's a small, but very worthwhile, expense.

May as well set the valve lash while you have the cover off, too. How long has it been since it was last done? Something to think about anyway. The correct pattern to set the valves in, as well as the correct spacing of the valves, is in the FSM. Something to consider, anyway.

The water pump can be replaced with everything in place on the engine. It's easier if you remove the PS pump from it's mount, and move it out of the way, but not strictly necessary. If you're getting even a small leak from out of the "weep" hole under the pump's main shaft, it's time to replace the water pump. Again, it's probably leading to a catastrophic failure.

The leak from the oil filter is easy to fix. Replace the filter Use a Toyota filter. Independent tests have shown the Toyota 90915-YZZD3 filter to be one of the best on the market, and yes, it will fit the 22R engine. Just make sure to clean the place the seal rides on thoroughly, to prevent leaks.

HAve fun!
Pat☺