Have a 1.6 8v in my samurai. I ran #1 dry  on a ledge and had it rebuilt. Added temp and oil press gauges after rebuild and once it's warm it shows 10-12 psi oil pressure at idle and 30 + while RPMs are up. May have been this way before rebuild. Any idea what's up?

Two questions ...

First - what do you mean you ran #1 dry on a ledge?
Second - what sort of a "rebuild" was done?

I don't have the FSM handy to get the specifics, but from memory, oil pressure with the engine warm should be between 45~60 psi (give or take 5psi) at either 3000 or 4000 rpm (I could look it up when I get home, if that would help), and experience has shown that an engine within spec. will show oil pressure in the vicinity of 20~25 psi at idle (say 750 rpm because it does vary with the engine rpms) again, when warm, so the pressures you're reporting appear to be on the low side, and that will typically be the result of excessive bearing (main & rod) clearance, which should not be the case directly after the engine was rebuilt - this is the reason I asked what sort of a "rebuild" was done - if I'm having an engine rebuilt, and it had a low oil pressure problem before the rebuild, I would certainly not expect that problem to be there after the rebuild, but you seem to think that that may be a possibility - in my book it's not.

I had the buggy at steep angle front was 6 feet higher than the back and I let it idle. Just after I finally climbed the ledge the motor started knocking on the way back to the trailer. I assume the front of the motor ran dry of oil given the steep angle. So I had the crank machines and new rings and the sort replaced to rid it of the knock. I hope this helped.

It gives me a better idea of what went on - the lubrication system is "pressure fed", so I would not expect the angle to cause the front of the engine to run dry - it's theoretically possible that you could get the pump pickup out of the oil, but if that did cause the problem, it would not have been just the #1 cylinder that was without oil, but the entire engine.  If I remember correctly the pickup is towards the rear of the pan, but I will double check that.

If the crank was machined and new bearings fitted, and the job correctly done, I see no reason why the oil pressure should be low, unless the oil pump itself was also damaged, which I suppose is a possibility if the engine did run dry.

Again, if I recall correctly, the manual documents a measurement procedure to determine if the pump is worn and under what circumstances a replacement would be required - if you don't have access to one, you can check Ack's FAQ for a soft copy.

What sort of oil pressure are you seeing with the engine cold and what grade of oil are you using?

It idles at 25psi and under throttle at 50psi cold. 10w30.

You've got excessive clearance somewhere, either the pump or the bearings, with 10w30 cold, you should be seeing in the region of 60+ psi at idle and as the rpms increase, the pressure should also increase until the relief valve opens, which is usually around 70 psi.

I think the easiest way forward is to plastigauge the bearings and if they're within spec., check/replace the oil pump.

A thought just crossed my mind - was any headwork done?  There's a restrictor in the oil feed to the head, if that is missing, it's another possible place for oil to flow more freely than it should.

I got the chance to look at the manuals - oil pressure spec is 46.9~61.1 psi at 4000 rpm with the engine at operating temperature, I was also able to verify that the "sump" on the oil pan (and the pick up) are toward the back of the engine, making it difficult to run the engine "dry" going uphill - maybe if the oil level was low ...

Did you by any chance notice if the oil pressure light came on?

The head was machined during rebuild. No oil light on my rig and at the time no gauge now i have one. Oil Level was right on  and gets checked before every use. Did the manual say what pressure should be at idle? I'm getting the correct pressure at 4000 rpm.

No - Suzuki does not provide spec for oil pressure at idle - the numbers I provided earlier were based on personal experience - I've owned a number of Suzukis over the past two decades, and they have all had oil pressure gauges fitted.

Any time I'm seeing less than around 20 psi at a warm idle I'm uncomfortable, but, I am aware that multiple factors can contribute to the pressure being low, for example, time of day & ambient temperature - on a hot summer day, the hours directly after noon can result in the idle pressure being a few psi lower than normal; idle rpm also plays a major part - the Mitsubishi in my signature has a GDI engine that idles at a lower rpm (600 rpm) than my Suzuki (750 rpm), and that causes the idle pressure to be a few psi lower than the Suzuki's, under the same conditions - Mitsubishi does provide an idle pressure spec - I don't remember the actual number, but it's somewhere in the 5 psi region - I'm not seeing less than 15 psi, and if I bring the rpms up to the same 750 that the Suzuki idles at, the pressure comes up appropriately, so I just accept the lower reading as normal.

Curiosity question - does "no oil light on my rig" mean there is no light, or that the light was not on?  As I mentioned, I fit oil pressure gauges to everything I own, I leave the light functioning - it's a lot easier to see when a warning light comes on, than it is to notice a gauge slowly drop back to zero -my wife & daughters also drive my vehicles, and whilst I know they will notice changes in sound and see warning lights flicker, I don't know that if they would notice that gauge changing - it's down below the stereo, so not exactly "line of sight".

Thanks for all the input. It's much appreciated. I think I'll just keep an eye out and maybe put a light in somewhere. I don't have an oil light on the rig currently. Only gauges are oil psi and water. Bare minimums. Here's a pic so you know what I'm working with.  It's not exactly a daily driver.

Side note. I called the shop who did the motor work. The old timer told me the OHC motors don't usually run very high pressure because they are dumping so much oil on top to lube the cam. Makes sense because it's hard to keep volume AND pressure up. Not sure it's exactly right but I couldn't argue. He's pretty long in the tooth and wiser than me.

I'm not going to question his experience, what I will tell you is that the numbers I've given you are typical of all the Suzuki engines I've had, and those were all OHC engines - the G-series engines (yours is a G16) have what is called an "oil jet" or "venturi plug" (essentially a brass restrictor) to limit oil flow into the cylinder head.  It screws into the oil way on the bottom of the head (where the head meets the block) and some people remove it if they skim the head.

Ahh ok. I wouldn't be surprised if that's the case. So pulling the head would be the only way to know. How would that be fixed. Will the oil jet still work if the head has been skimmed?

I can't think of any other way besides pulling the head - if it's not there, you'd have to get one & install it (P/n #11112-73001) - I don't see any reason why it should not work with a skimmed head, but that might depend on how much was removed.