Psyte

since changeing my oil for the first time in my new engine, i noticed when i was on the highway the needle was almost pinned at 420(i think thats the number). there isnt a red line there or anything, but this cant be good can it? at idle it stays at about half way. it USED to be at 3/4 on the guage at highway speeds. any ideas on why its doin this? could i have put too much oil in on the oil change? i just bought a 4 liter jug and dumpped it in. (yes i did the oil change correctly, filter, engine cold, oil cap removed) im so paranoid when im driveing i cant take my eyes off the oil pressure guage. the engine sounds fine too

Cruzin Kaz

Well for the most part the more the better. Oil pressure that is. If the gauge is staying right at the top your OK. Not to worry. And if you only put a 4L jug of oil in you almost got the oil change right. Your car should take more along the lines of 5.5L to 5.75L depending on which oil filter you have on. I would check your dipstick when the engine has cooled off. You most likely are a litre or so low. HTH...All is good!

The thing you want to worry about is really LOW oil pressure when your on the throttle...When you see that...then you start to worry.

Slow2.8

that's when your engine is bout to be history.... just like fords when we race em

MdFormula350

umm i dont know about you guys, but i always do an oil change right after a long drive..

82camaro

If you are concerned about the pressure, verify it with an aftermarket mechanical guage, and give us the reading. A new engine is going to have more pressure than an old one. The lower the rpm, the slower the pump turns, so pressure will reduce at idle. What kind of pump did you install? What weight of oil? 4 liters is about 4.25 quarts--it should hold around 5 quarts(4.75 liters).

RJR99SS

well i can assure you that it wasnt 420 psi. The oil filter usually blows off at around 90 psi.

A high oil pressure isnt necassarily better either, it's actually just wasted energy as it dosnt need to be that high in all but extreme cases.

Cruzin Kaz

He didn't mean 420 psi..he meant kpa. As long as it isn't staying at 420 when idleing, and it seems to run well, I wouldn't worry. But out of sheer curioustiy maybe you should get a aftermarket guage and hook it up to see. My rebuilt TPI L98 motor, at idle moves around 10-20 psi which is nornal at idle. When at 4000 rpm it's pressure rises to 45-55 psi. Which is off a stock pump. I like seeing the high of pressure. If it were to go over 60psi at any time I may get a tiny bit worried.

Psyte

actualy, today when i got of work, i started it up and it slowly rose up to just under 420, and it stayded there constantly untill i hit the highway wich it actualy hit 420. thats the highest the guage goes, that just doesnt seem good. eventualy after 10 minutes of highway driveing it went back down to 3/4 and looked normal again (half at idle). i dont know whats up with it. i have no idea how to test it without the sensor. im gona check my oil later today. i dont know what kind of pump it is, it just came with my rebuilt engine

92 heritage z28

gauge could be throwing the computer a bad reading, maybe have a shop confirm that reading is correct, have heard about readings on the high end not being accurate

82camaro

Originally posted by Psyte
actualy, today when i got of work, i started it up and it slowly rose up to just under 420, and it stayded there constantly untill i hit the highway wich it actualy hit 420. thats the highest the guage goes, that just doesnt seem good. eventualy after 10 minutes of highway driveing it went back down to 3/4 and looked normal again (half at idle). i dont know whats up with it.

nothing is 'up with it'. That's normal. When the oil is cold the pressure will be high, then when it warms up it will drop. Mine shows about half the pressure when it's fully warmed up, compared to when I first start it. 420 kpa is about 60 psi(if my math is right). So you run half that at idle (30 psi) at 3/4 that at higher rpms. Sounds good to me.

ede

the oil or any other gauge doesn't run off of or have anything to do with the ecm. if you want to see what yuo really have screw a mechanical gauge into the block.

Vader

And just so that we're all on the same page, for reference, 420 KPa is 61 PSIG (actually, 60.91585, to be exact).

And 5.0 quarts (US, not Imperial) is equal to 4.75 L (or 4.731765l, precisely).

If the gauge is reading 61, it might not be a big concern. Mine reads 60 PSIG with 10W30 Mobil 1 at anything above 1,400 RPM. I guess my engine is still too tight at only 48,000 miles. Then again, the factory dash gauges are nothig to brag about for accuracy.

92 heritage z28

true, mech gauge will be the final anser, but computer does sense water temp i believe, just figured oil pressure would go through computer also.shop hooked up computer in my car showing me water temp was off, figured they could read off of that showing weither oil pressure switch or gauge or whatever was wrong.

swerve-driver

I agree with 82Camaro

Likely just be a combination of the ultra-cold weather and the new oil. Maybe the old oil was trashed and thin. I based this on one of your last comments that after highway driving, oil pressure went down.
And the comment about the stock gauges not being so accurate is a good point also.

If its as cold or colder up in Canada than it is here in Chicago, the cold, thick oil thing is probably right on.

It was only 3*F here in Chicago last night. Dang!

S-D

Vader

If you think that was fun, wait about ten-twelve hours.

I agree that the cold, clean oil that hasn't had all the viscosity modifiers (polymers) burned out of it yet will tend to register a higher pressure on the "laboratory quality" factory instrument (and I use the term "instrument" loosely as well). What a fine piece of engineering that is. Matches teh temperature gauge perfectly...

Psyte

well, all i know, is when this car was tpi, it never got that high on the guage through out the seasons. is this a carb thing mabey? could it have anything to do with the timeing? or that its a freshly rebuilt engine? im running 10w30 just so you know. as long as my engine isnt gona blow then im happy. by the way, how would i know if i broke in my engine wrong? and is it normal for carb engines to have a slightly unstable idle? mine bounces up and down about 10 rpm (id guess) every now and then at idle. ive ajdusted everything acording to what ive learned on here and other books/manuals. but i did spend most of this engines break in period tuneing it and testing it, so did i break it in wrong?

82camaro

Vader

Psyte,

Engine oil pressure has nothing to do with timing, adjustments, or the type of fuel delivery system. It is strictly a function of engine RPM, the viscosity of the oil, and clearances in the engine. Viscosity will be affected by temperature or the base viscosity of the oil. Clearances in a new engine are going to be tighter, so a lower volume of oil pumped will maintain a higher pressure. And the oil pump output volume and pressure relief spring do the rest.

Basically, as long as the dash gauge agrees with a separate mechanical gauge, and you have that kind of pressure, you're "being paranoid". You probably didn't do anything wrong in the break-in. If anything, you might want to switch to a 5W-30 in colder temperatures to keep the presure down a bit, but if you go that low, I'd suggest a synthetic to provide the best protection once the engine warms up.

Psyte

im not sure about numbers, but all i can tell you is its a shadbolt roller cam. i bought the engine rebuilt. thankfully im not blowing any smoke though. the whole ignition system is brand new. im useing a pro-form hei coil in cap distributor, and msd wires. i have the timeing advanced 8 degrees(by the way, how am i suppost to know how much to advance the timeing by?)