Oil Pressure and RPM Drop

stirling33 · May 30, 2006

Over the weekend while driving my car every time I would come to a stop, the oil pressure would drop to 25psi and my rpm would drop down to 500-600 or so. This has never happened before and my car has always run at 50psi and 900 rpm while idling. What is causing this, and is there problem somewhere?

69Rcode_Mach1 · May 30, 2006

Your idle at 600 is a tad low, but 25psi oil pressure is just fine. Mine starts at 60psi then it warms up and comes down to 30. Sounds to me like your car is just warming up which causes the settings to change. You need to tune the carb with the engine warm, you may have tuned it while it was cold.

jbuening · May 30, 2006

Are these high pressure oil pumps? Mine is 50psi cold, and then once hot and idling its around 15-20.

iskwezm · May 30, 2006

jbuening said:
Are these high pressure oil pumps? Mine is 50psi cold, and then once hot and idling its around 15-20.

me to, but mine drops to about 10psi when warm at idle

69Rcode_Mach1 · May 31, 2006

Nope mine is a standard oil pump. I am running 10w40 oil though. Iskwezm 10 psi is a little low, it's not terrible but you should generally atleast have 15psi at idle.

jbuening · May 31, 2006

You are getting 30psi at idle (7-800rpm) when the motor is warm and with a standard pump? What's your secret? lol I can't imagine getting 50psi at idle when warm, that can't be good on the bearings.

69Rcode_Mach1 · May 31, 2006

My idle is slightly higher right now till I can get 1000 miles on it and throw it on a dyno, and gear the car properlyk. I am idling around 1000rpms, but I don't think that makes that much of a difference, maybe 5psi.

MustangMatt1966 · May 31, 2006

yeah, i get 30 psi warm at idle with a mechanical pump....

stirling33 · May 31, 2006

I guess my concern was that whether it was warm or cold it always ran at 50psi, but know all of a sudden it drops to 25psi once I come to a stop. So it sounds like this is a normal occurence for everyone else. I guess I will just retune the carb to bring the idle up.

jbuening · May 31, 2006

Believe it or not, the change in oil pressure from 500rpm to 900rpm could be close to 20-30psi. My car idles around 750-800 and i get around 20psi warm. Whenever i pull up to a stoplight (applying brakes), my rpms drop to 5-600rpm and my oil pressure drops to about 12psi. When stopped the idle goes back up to normal and so does the oil pressure. Cruising at 1200-1600psi i get around 40-45psi.

Is your motor still pretty fresh or does it have alot of miles? Fresh motors will naturally have higher oil pressure until it gets broke in, and then the pressure readings will drop (and continue to drop as the motor wears). Hope this helps a bit. I have a mechanical oil pressure gauge so readings are easy for me

69Rcode_Mach1 · May 31, 2006

Mine is mechanical as well. But yes the motor is fresh I only have 260 miles on it right now. So I have a ways to go before I can really say it is broken in.

stirling33 · May 31, 2006

So in conclusion......theres nothing wrong with my car.

MustangMatt1966 · May 31, 2006

stirling33 said:
So in conclusion......theres nothing wrong with my car.

correct

iskwezm · May 31, 2006

69Rcode_Mach1 said:
. Iskwezm 10 psi is a little low, it's not terrible but you should generally atleast have 15psi at idle.

I realize that but im not going to tear into this engine with barely 800 miles on it, when it doesm then i will look at why

LMan · Jun 1, 2006

MustangMatt1966 said:
yeah, i get 30 psi warm at idle with a mechanical pump....

A mechanical oil pump, huh.

..is there another kind?

MustangMatt1966 · Jun 1, 2006

LMan said:
A mechanical oil pump, huh.

..is there another kind?

haha shhhhhhhhhhhhhhhh

Oil Pressure and RPM Drop

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