Oil pressure problem

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72firebirdguy

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One day on the way to checking the mail the oil pressure suddenly just dropped to 0. normally when its warm it'll hold about 35 pounds. when we push it about 25 pounds. so we bought a new oil pressure gauge and it said the same. do you think it could be a cracked oil filter housing? the pressure line is connected to the filter housing and is a mechanical gauge. ive heard of loose oil pumps too. do you think it could be loose? but im really hoping the motor dosen't have to come out. the weird thing is its not ticking or making any noises. i have the PCV hooked up to timed spark on my carb could it be that its doing such a good job at ventilating that its affecting oil pressure?
 
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PCV has nothing to do with oil pressure. How many miles on the engine? When you push it I would expect at least 50 pounds of pressure. If it's high mileage you can replace the pump and at the same time inspect the bearings.
 
it was VERY sudden. warmed it up then checked the mail then it just dropped. id say less than 10,000 miles on rebuild. i mean 25 pounds at idle after we push it HARD. not under load. under load it does 50 easy. at normal temp it will hold 35 at idle and at cruize 55-60
 
what i meant was that could the vacuum for lack of a better term "balancing" the oil pressure? or atleast trick the gauge to think that its not holding oil pressure because of all the vacuum being introduced to the crankcase.
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my thought was that since the other valve cover is sealed with a grommit and does not have a breather there would be no escape for the vacuum so it would build up and eventually "balance" it.
 
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Now that you give the full picture both idle and cruise, there is nothing wrong with very hot oil dropping to 25 at idle. What weight oil are you using, 10W40, 5W30, etc.? Again even with the other cover missing the breather, you should have one, it will not effect oil pressure.
 
sorry i should have been clearer. Normally when hot it will hold 25 at idle. but the gauge reads 0psi at idle even when cold and will go up to like 10-15 pounds if at like 1500 and there is no knocking or ticking.
 
"Normally when hot it will hold 25 at idle. but the gauge reads 0psi at idle"

How do you know it holds 25 at idle if the gauge reads 0 at idle?
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what i meant was that the gauge showed 25 psi at idle. then it suddenly just dropped to 0. didn't push the car at all. i was put puting around to my mail box down the street. held 25 psi. turned the car off . got the mail. turned the car back on then it read 0 psi
 
any chance since you hooked this gauge up you have air in the line leading to it? Was the first gauge a recent addition?
 
no it is full of oil no air bubbles. and also now it will hold 10 psi when cold. and will go up to like 45 at 1500 rpm. the gauge was put in a little less than a year ago. i tested it with another gauge that i know works and got the same reading.
 
what weight oil are you using?
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Did you do the rebuild? With that weight oil you should be getting at least 30 PSI cold at idle, 20 when hot, 10 sounds too low. It may be worth dropping the pan and seeing if the oil pickup is not properly seated in the pump.
 
i personally did not do the rebuild but every thing on it was new. the heads had even been cut for pc seals which is not stock. yeah probably gonna pull the motor drop the pan and hope that it is the oil pump and not something more serious like my last motor was. my last motor had 273,000 miles on it and held 5 pounds when warm. it was getting ready to spin a rod bearing.
 
there is a 70 persent probabilty that you oil pump is s!@t... possible not primed corectly after the rebuild... definately check them bearings and prime the new pump if you replace it...
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You say you replaced the guage? What about the sending unit? Also could be your pump. My pump went on my LT1, got 0 pressure at idle, but I was still getting pressure above 2000 rpm., and my motor made no noise. What year car? and motor size?
 
1972 firebird. with a pontiac 350. gonna pull the motor tommorow and replace the oil pump and rod
 
0 oil pressure

Hi again...If you truly don't have any oil pressure, then the oil should not be making its way up to the heads. If you haven't already, try taking the valve covers off and then fire it up. If you have oil spitting out of your heads, then you have pressure. Prepare for a mess, and drape some towels over everything before you crank it over.
 
all fixed the oil pump was bad. the bypass was stuck. lucky i already had a brand new oil pump from a rebuild that did not happen. primed it now it holds 60 pounds!
 
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