After long drives the oil pressure is still high 35lbs@1000rpm 55lbs@2300rpn stock rebuild 350 /no adjustable oil pressure thingy. ya think its a spring fix or a gasket fix? (i don't know whats in the pump) Cheers!
What weight oil are you using? What filter? (manufacture and part number) The oil pressure relief is set to 40psi, so 35psi at 1000 RPM is not too high, nor is 55psi @ 2300 What is your cold pressure at idle in gear and in park, at 1000RPM, and 2300 RPM? If you see PSI at 80 or more, then there is some concern. Oil pressure is a result of "resistance" to oil flow through the engine. Anything that impedes the flow will increase pressure. * The reverse is true that anything preventing resistance (excessive bearing clearances, breach of any oil passages, etc., can result on loss of pressure). * (* both above have exceptions...) If your idle pressure is between 40-60 cold, and 20-40 hot, you are in a good place. As long as the oil pressure is fairly steady at any RPM, increases/decreases with rise and fall of RPM, and has as a "ballpark" 10 psi for each 1000 RPM, then you are pretty much in the "green". Big swings with no change in RPM, delay of more than a few seconds of oil pressure when starting, cold or hot, or valve train or lower end noise that "comes and goes" from startup, and/or when hot and at idle, should be investigated.
This a stock original untouched engine? If it’s been rebuilt, do you know what the main and rod clearances are? 35 lbs is quite a bit for pressure at hot idle for a Buick, it’s not typical hot idle pressure. It could be too tight main or rod bearing clearances. Exactly what trunk monkey was alluding too, pressure is a measure of restriction, but it’s really the only way we can observe trends in oil flow that’s economical, indication of flow would be better, but flow meters are relatively expensive. So we use pressure gauges for water, oil, air, etc. If your bearing clearance is on the tight side, it’s more of a restriction to oil flow (takes the oil longer to squeeze thru the clearances) so the oil essentially backs up creating more pressure but less flow. Looser clearances create less pressure cause the oil is moving pretty quick thru the bearings but the pressure is lower and flow is higher.
never seen a stock 350 with that psi at idle. higher rpms do need more psi because of the way the system was designed. i run a blower on my 350 and idle psi is above normal and wot is 80-100 psi. i use plain 10-30 amsoil. did the t/c gasket slip when installed and blocked some of the hole?
Sounds perfect. On a fresh rebuild on a 215, 300 or 340 with the oil mods and tight clearances I have 30-35 at idle warm, 55-60 at 2500 RPM with 10-30 oil. 60 lb relief spring.
Mart, Not that tight. .001 to.0015 on rods and mains. Forgot to mention under .002 oil pump to booster plate clearance.
It's recommended 11 psi per thousand RPM your way ahead of the game. What's your oil pressure at five grand ?
Yep Jim, I like less than .002 on rods & mains. I'm at .0015 & .0018 .0015 on pump cover. Got 20 hot 750 idle in gear, 40 hot 1,150 park. 50 at 2k. on up from there. Gauge moves like my tach.
To run those minimum clearances you would need no runout, no eccentricity, no taper and no micro chatter marks on the journals by a very meticulous grinder.
4 qts Mobile 1 10-30 2 qts Mobile 1 15-50 53lbs@3000 rpm 75 lbs @ 6 grand. Never used any other oil 26 years on same build.
15-40-rotella. It’s a little much. Just idiot light. But leaks a whole lot on ground so pressure got to be good
As far as Buick engines are concerned, there is NO SUCH THING as too much idle oil pressure. If you are topping out above 80 psi at HIGH RPM, you might want to turn it down a little. Having said that, your true idle pressure is in gear, AFTER you have driven the car at highway speeds for a minimum of 30 minutes in hot weather. That is when your oil will be at the highest temperature. If you just let the car sit and idle in your driveway until the coolant temperature stabilizes, then look at your oil pressure in Park, that will not give you an accurate hot oil pressure.
I have had big block FE Fords blow off and balloon the oil filter when the relief valve stuck. Gauge went to 100 so it was probably more than that. I've never had it happen with a Buick, but the 300 stroker I helped on did. Balooned the filter but didn't blow off, cold start up pegged the gauge. After cover and relief valve changed, back to normal.
I shoot for .0012" on my rods and mains. Run 10w30, pressures about like you guys are seeing. May consider a lighter oil. Jim
1. 1000 RPM isn't "idle". What's the HOT oil pressure at 650 RPM? 2. I know folks that would pay money for that much pressure. 3. How do you know the gauge is accurate?
