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Idle Oil Pressure
96 x90, G16B (16v) 4x4 Manual.

On start up great oil pressure, anything above idle great oil pressure as expected. After it gets warm though the idle oil pressure drops to 10/12, but pops right back up as soon as I tip in on the gas pedal. I have a nervous breakdown every time I come to a stop light due to this indication. Is that normal for one of these engines? the few things I've read have loosely suggested the oil pressure should never dip below 20... thus my concern. Did some searching here and couldn't come up with a more specific line of information.. any insight would be appreciated!

Fully rebuilt engine, block and head by a very reputable engine shop who have done many of these same engines. I've got a full array of excessively expensive Autometer gauges so theres no reason for me to doubt the gauge indication being accurate.
1. 10w-30 (for now)
2. Yes this only happens when engine is hot
3. - confused by this comment, if 20psi rule is bunk do you mean it doesn't have to be 20 @idle?
4. engine idle is correct (somewheres around 800/900)

Truth told I have no idea/experience with the bearing specifics so you lost me completely there (why I had a reputable shop do the work)

Is this low (12ish psi) @idle catastrophically wrong?

Going to keep an eye on the gauge specifically today and report back. If memory serves me correctly oilpsi is around 52 @4000rpm, around 45 @3000rpm.
see my section on using that oil port on the block it is not trivial , as Suzuki used British spec on that threaded hole. (the history on that is funny but I digress there)
Ok- I've been monitoring the (aftermarket) in-dash gauge over the weekend. Calling Autometer tomorrow to find out the variance of both the gauge and sender Monday, also have a bourdon gauge on the way. I was aware of the BSPT and have an adaptor so no stripping or leakage there, will report back with further info on those items.

My more attentive monitoring has left me only further confused;

On cold startup I get extreme oil pressure. 65-70ish, as high as 80 if I tip in on the gas to raise the RPM.
Stays high (60ish+) until things start to warm up.
Once hot (180) it settles in as "expected" and doesn't move over 55/56/57ish, no matter how hard I get on the gas or under load.
@4000rpm settles in around 52ish
@Idle still around 13/14.

PT2- I'm making a hour long all highway drive to work currently, after 15-20ish minutes of highway time:
@4000rpm drops down to around 46
get off the highway
@Idle is 10-12. (has panic attack)

stopped for 5 minutes at a store:
startup-idle 13/14
non-highway @4000rpm, back up to 52ish.
stoplight idle 13/14.

This sequence of variation in results happened 4 times (the oddity of highway vs city after stopping the engine for a short time)

I'm aware that 60/70+ even cold startup is definitely incorrect, so I was leaning towards pressure relief valve issue, but the variation of excessively high and well under has got me completely baffled. Has anyone experienced a "sticky" (for lack of a better word) pressure relief valve, and this kind of vacillation of readings? Is it possible for the spring to weaken or the valve to wear, that might cause inconsistent opening or closing when cold, and hot? Oil pump condition I don't know, the original was put back on after block rebuild, so its possibly to blame, I'm not opposed to replacing it and hoping/praying its the culprit. Anything else that anyone can think of that could possibly be causing this? I'm confident in the build on both the block and head, but will check in with the tech who did the work again monday to reconfirm assembly specs. super stressful considering my intent is for this to be a daily driver.
Autometer oil pressure gauge variance: +/- >2% @full deflection.
Engine builder confirmed they do a 2-pass verification on all machining, builds and assemblies.

After discussion with engine builder on my findings, ordering a new oil pump and hoping thats the cause.
10psi is not bad, in and of itself.
no gauge model stated at a all, nor if 60,80,100,150 psi gauge? (60 is best)
no gauge technology stated, oil pipe line, or sender electric + guage. (no clues,)
no makers of oil, syn, dino and brands of oil, try Chevron Delo 15w-40 if you worry pressure at any engine temp.
MOST gauge is not accurate at 10PSI , that 2% is at full scan only.
A real shop uses a direct connected to the block gallery plug and uses a real; Borden tube meter. not consumer grade toy meters (they have there place cheap meters, but not for real diagnosis)
never pull and engine for the reading of one cheap consumer grade meter, . use a real shop gauge.

do you know how to test your meter for accuracy at 10PSI,, it is easy with shop air, and a regulator and real guage to set it. or just use a real guage and autometer is NOT IT.

the block oil sendr. port, is not NPT threaded, but is BNPT. (British pipe tread, Imperial oddity) do not cross thread it using USA NPT standard treads, the block is aluminum and not iron.

here is the best place to ask, bob the oil guy join and ask. but you fail testing methods , so is first things first error, get a real shop guage and learn to test the correct way. IMO


the above uses google site: search trick to find all oil pressure issues.
this post is only hot idle pressure, so.. that is my answer.
if real gauge at block using bourden tube analog gage fails..

1:the oil pan pickup screen tube -oring missing or cracked?
2: the oil just does that, as some can, hot.?
3: engine clearances way to large (they add up one bearing at a time to a total flow)
4: bad pump, ? id think not but why rebuild and engine with an untested oil pump.?? how odd is that and many china clone pumps are pure crap.
5:the pump bypass valve stuck open, well its part of pump so.... moot point here, but is a POINT of failure in the system.
6: oil temps over 270f?
7: OLD oil the dash 40 at the end is what is called the Shear strength of the and drops on old oil. (too many miles, (over 7k miles)?
8;: gasoline (petrol) in the sump oil pan.? or water, or overfilled the pan (wrong dip stick) and oil is aerated, (foams up) and pressures drop, (pump does not like that nor do starving bearings)

that is all I can think of now....
Eugène Bourdon patented his gauge in France in 1849, and it was widely adopted because of its superior sensitivity, linearity, and accuracy;
no electric guage sender will ever come near the accuracy if the , above gauge. ever. (that you can afford)
the reason we use this Bourdon guage, is its very accurate and low cost, and every shop has one for this reason, why not you?
a 0 to60 PSI guage would be the most accurate .


the electric sender gauge, the sender has cheap carbon POT inside, that has very crude design. and is not accurate for sure in the lower pressures.
An electric gauge has its purpose, you drive every day and sure readings are wrong, every day but one day you see a change, this is what cheap gauges do best. see a NEW CHANGE.
it is never used for shop diagnosis any electric gauge, for sure consumer grade cheap junk.
you can see a the autometer web site it is just consumer toys..
no real spec,
no linearity spec.
no accuracy from max to 0, just %2 of full scale +/-
if you learn to test things like this you learn like me it is way off at 10psi. even by +-50% so 10 can be 15, or even 5.
by doing tests we learn to avoid cheap tools and use real shop tools from Proto or snap-on or any top grade tool.

In shop testing and engine a wise tech, would never trust 1 tool.
He or she will then test the suspected tool using methods stated above (I use shop air tests)
or go the tool bin get the real Bourdon gauge, that gee worked prefect just last week and see if it sees low oil pressure too.
A was tech is a very suspiciou tech, he always challenges him self and his tools , Am I testing wrong ( you are) and is my tool junk (it is) bingo? sorry but that what we do (the science and practices of testing)
what I see at Autometer, are fibs by omission, a skilled tech sees the spec missing key facts. (for sure the sender spec. is toy grade for sure)
here is good gauge and not expensive to have in a shop as at least a backup to better gauges. ( a real shop gauge is rubber covered) but this is good one to use for sanity tests. ok?


the correct adapter for USA pipe is

BSPT 1/8"-28TPI (threads-per-inch)


NPT on the outside, of the adapter and BSPT into the block male in to block , with no damage.
this is how it is done the correct way.

hope this helps.

there is no hot idle spec, on the G16 engine for Oil pressure, against all classes of oil sold in the market 2019

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