oil Pressure Sensor

[Kim K Kaiser]

over weekend, i found some oil leaking from behind the valley pan.  As some of you know, changed all that out back in oct or so and noted the oil pressure sithc was so low to the block that is seemed to inhibit a full flush connection, but didnt think much of it until i finally had some time to do so more searching for that leak,  (again from prior many post).

Anyway, i had purchased a NOS from Russ and i could see a big difference in the construction, so i decided to change the valley pan out again get a presumed flush fit and stop that leak out the bak of the valley pan..

so i got every thing changed, noted the valley pan quite leaking (yeah!)  at least for now, and went out for a ride this morning.  

as i would approach a stop sign or hit brakes to get to almost a stop,, my oil light would come on!!!! as soon as i tapped the accellearor, it would cut off immediately,,    

i thought WTF now.. 

so, i did some drive testing,,,, here is what i found.

driving,, hitting gas, hard, or intermittent or driving at 70, or just coasting from 70 to almost a stop,,,no oil light.

zipping around town, as one would typically drive,, no oil light, EXCEPT, when i almost got to stop and had to hit brake to fully stop at a sign or light,,but again, as soon as i hit accelerator, even just a tap,, the light would disappear.

Since my other sensor or since i never had a oil sensor light problem before,,, can someone shed a little light on this please..    again, this never ever happened prior to this change out, 

[Kim K Kaiser]

No.  No clattering.  It happens right before the car comes dead still.  Depending on how high i hv the accelerator nuts set, determines if it just flickers or stays on  or does come on at all,  

[Kim K Kaiser]

ok, hooked up to gauge

start up,, 30 psi  as it warms it got down to around 12 to 15,

took for ride.   up to about 55 or so, the oil pressure was around the 20 psi range at cruising speed,

at full stop, in gear, at a stop light...  about 9 or 10.   

going to put the sensor back in, giving the current accel set up and see when the light comes on,

but that is what the car ran at on the gauge.

[Kim K Kaiser]

I just cked my rpm again.  

At 450.  500.  In drive,  im holding 10 psi.    Good,  Bad?

[Kim K Kaiser]

Ok,  given the numbers rom the gauge

How to proceed?

Change filter?

Change oil and or  to heavier oil?

Ck and/or improve regulator spring?

I can only assume expensive repair beyond the above

[Kim K Kaiser]

back of pan leak is marginal.. i dont really see it leak DURING car operation,, only after i park it,, usually doest even hither concrete,, just hangs off the inspection plate,, 

yes, check oil regularly  

[Kim K Kaiser]

just as an update,,, i changed the oil filter, hooked up the gage and went for a ride.

startup,, 29 to 30 psi,, let it warm up to fully open choke,, dropped to about 27.

took off, typical around town driving,,, driving pressure was around 25 -27,, the more i drove, the more the pressure dropped..   before my ride ended,, i was pretty much driving at about 20 psi,, pressure at stop light idle was at 10, if is sit there,, it goes to about 9.  

what i also noticed, the longer i drove and the longer the pressure was lower,, at take off, it was more inclined to knock a little, so thinking not getting enough oil,,

i decided to pull it in a park it.

next step to put those washers in the regulators, and then the engine wash out,  

at the time of the oil change after the washout,, i guess I'm going to stick my snake light up in the engine to see if i can get a look in the oil pick up,, see if there is anything in there,, i know from the first time i opens the bottom of the engine, it had lots of gunk in it,, i dont know if i cant work it up in there, but will try if other parts dont get in the way.. 

I'm just confused a bit about why the longer i drive it, the lower the pressure seems to drop ,,is it due to the oil continuing to heat up, and where is the pressure leaking to,  or, is something blocking the pressure,, either way,

heres to hoping the washers will give me a hopeful christmas..

[Jason Edge]

Shop manual is specific - at idle 10 psi, at 30 mph at 30 - 35 psi. I don't know what "driving around" means. Let engine warm up and drive to 30 mph on flat level road and see what psi is at?  Your at idle is very very close to spec.  I would personally not be worried at 9 psi unless it continued to drop further . The oil is going to continue to "thin" as it heats up until it reaches norm operating temperature.  If your temp gauge stabilizes and psi continues to drop under continued similar driving condition (30 mph on flat road) that might point to another issues. 

Back to your Original Concern - the Oil Pressure Light. The oil pressure light should not come on until oil pressure drops below 7psi. I have not read where your gauge is reading less than 9psi.  so you might have a bad oil pressure sending unit if light is coming on when pressure drops to 9 psi or 10 psi (normal) at idle. 

[Kim K Kaiser]

U know!  Driving around!  Go to mcdonalds,  go to part shop, cruising thru town, seeing if anything is going on. 

But to your notes,  im clearly not getting the higher end oressure, barely if at all at startu . 28 or 29,  and whilecdriving,  28 then lower, then lower.  At 35, its nowere near 35 after everthi g in warmed up.  Maybe 18 to 22.

[Jason Edge]

OK, Kim... i'll try it again.. If your engine is warmed up, and you are driving on a flat road at 30 mph, what is your PSI. Even in my Escalade with the 6.0 Liter LQ9 engine just driving around psi is up and down as I stop and go, shift gears, go up inclines, go down declines, accelerate, or decelerate. Driving around really doesn't tell me anything. That is why they state a benchmark, 30 mph. 

[Kim K Kaiser]

Under no circumstance do i go over 22psi may be 23 at 30 mph.  

[Jason Edge]

OK. so "may be 23 at 30 mph." Not to beat this to death but I would have warmed up the engine, got a reading at idle, found a straight stretch of open flat road, pegged it dead on 30 mph and got my reading. The stop and go just driving around doesn't really tell you anything other than that you see how oil pressure changes in various driving conditions.   The other thing is if you got your exact readings you can note it and then take another test and compare at a future date. Anyway.. hopefully I have made my point. Assuming 23 psi on a warmed up engine, driving on flat road at 30 mph then, yes you are off a bit (7psi) from stated spec. You could also have accumulated debris in the oil pickup screen. Of course checking that would mean dropping the pan again. Even though your oil psi is just a tad low on idle and moderately low at slow cruising speeds, unless you here valve, rod or other noise I might run some Marvel Mystery oil thru the crankcase for about 500 miles, and stop and change oil and filter again. If your oil light is coming on at 9 psi at idle it is defective and should be replaced. As noted in my last reply the light should only come on when oil pressure drops below 7psi. If it is coming on at 9 and 10 psi it is giving you false warnings.

[Kim K Kaiser]

I understand the need for specificity to manual requirements, and i did run at that benchark. I also pulled the oils pump, and regulator. I had forgotten i had bought a replacement kit couple years ago, and it had a spring in there, it was about one quearter to three eitgths longer than the one currenly in there, so i put it in, added a washer and closed her up. I thought the spring ize may hv had some effect since adding a washer wash part of reason for the pullingvof the regulator.