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Discussion Starter #1
Just wondering my 302 has about 1000 miles on a rebuild. When I start the engine in the mornings the oil pressure is on the high side and the cam (512 lift) is sounding good hitting like it should. Then when the motor warms up to to normal running temps the cam goes from sloppy like it should to sounding like a stock cam.The oil pressure is then on the low side. I cant figure it out Im running 10-40 castrol and the cam is made by Crane. Also when I first rebuilt the motor I put a Fram filter but it kept blowing the seals out so I went back to Motorcraft no more problems. I dont every here any lifter ticking are anything like that. Any info would be helpful.

Thanks Harold
 

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your oil is fine. when you say "on the low side" have you put a mechanical gauge on it to see the real oil pressure? and your idleing issue sounds like a tuning problem.
 

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First thing that you need to do is install a mechanical oil pressure gauge. You need to see what the actual oil pressure is. Then a better diagnosis can be made.

Another thing is more info. What kind of lifters are in the engine? Hydraulic Flat, Hyd. Roller, Mechanical Flat (Solid) or Mech. Roller? Is the oil pump standard, high volume or high pressure? What kind of rocker arms do you have? Standard of roller?

You will always have a higher oil pressure in a cold engine. When everything is at normal temp., everything has expanded, clearances change, oil flows easier and oil pressure will slightly go down.

What bothers me is the fact that you're blowing seals on the oil filter. I know that Fram filters are a POS, but this shouldn't be happening. This is one of the reasons why I suggest that you install a mechanical oil pressure gauge, even if temporarily, to see just what the actual pressures are.
 

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By 1000 miles there should be no need for any break-in oil. The viscosity you are using should be fine.

The stock Ford oil pump has a 55 psi regulator valve. When the oil is warm and at idle the pressure will usually be less than that since the oil has thinned. That is entirely normal for almost any engine. Motor oil at 200F is about 20-30x less viscous, i.e. thinner, than at 70F and the pump would have to put out 20-30x more oil at 200F to maintain the 55 psi than it does at 70F.
 

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Discussion Starter #6
Thanks everyone for the info sorry for not being more detailed in my information. I have a hydraulic flat lifters and a stock oil pump. The car did have a solid lifter cam and lifter set in it before I changed the cam out. The only time the fram filters would blow out was when it was cold and the motor had not be started up in a couple days. Like I said I went back to motorcraft no problems. My next days off I will try to put a gauge on the motor.
 

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The reason that I'm showing concern about the filter gaskets is there may be a problem with the relief valve in the oil pump. A sticking refief can contribute to pressure spikes, especially at cold start up.

When you install the gauge, pay special attention to the oil pressure at first start up with a cold engine. Of course, it would be good to know the operating pressures through a complete warm up cycle and the pressure at idle after a highway run.
 

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Discussion Starter #8
Sorry just getting back with the answer. I had to put the project on the back burners. I have a new addition to the family on the way. The oil pressure shows 50 psi on a cold start while the the engine warms up the oil pressure at idle is running about 10-15 psi. Any information would be appreciated.


Thanks Harold
 

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that 10-15 warm is a little low harold. are you still using the 10-40? combined with possible pressure spikes like greek mentioned you may have an oil pump problem. maybe change the oil again and keep a very close eye on it. :bigthumbsup
 

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Harold,

The pressures you report don't sound out of line to me. The original Ford gauge was so squirrelly that you often could barely tell the difference between 10 and 50 by looking at the gauge. For a new engine they might be a little low but then I don't know the accuracy of how you are measuring them, what you are defining as 'warm', etc. A 4:1 difference in idle oil pressure from cold to hot is not at all unusual.
 

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Discussion Starter #11
the pressure readings are coming from a extrenal oil gauge hooked up to the sending unit. like I said the pressure is fine until the motor warms up to normal running temp. the qauge was showing 10-15 psi when engine is at normal temp. I hooked up a external oil gauge to check the pressure just for this. I know you cant go by the guage in the dash.
 

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I believe 10-15 psi is too low but I am not an expert. My engine will never go below 25 psi at idle. I have a quality electric autometer gauge.
 

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The only Ford spec from the shop manual for oil pressure is at 2000 RPM: 35-55 psi when 'hot'. Hot is not defined. Pressure will always be lower at idle.

Most owners seem to not understand that hot idle oil pressure can be much lower and is perfectly normal. That is why Ford was putting idiot gauges in their cars a while back that had only two needle positions: Off and On. The gauge looked real but was no better than an idiot light. They thought that was easier than answering all those questions about 'why is my oil pressure low at idle'.

Applying the 'rule' of 10 psi for each 1000 RPM an idle pressure of 10-15 psi is not a problem. I have cars that idle with much less pressure and did so when they were new. It depends greatly upon bearing clearances, etc., which are different from one engine to another.
 

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Discussion Starter #14
The only thing im trying to correct is when my engine is "hot" my lifters will start to rattle and I was wondering if it was from the low oil pressure. I have built many engines in my life and have never seen this in a ford engine thanks for the information. Im just wondering if the oil pump has clearance issues between the between the inner rotor lobe and outer rotor. I might just change the out the oil pump out. I should have change out the pump when I rebuilt the motor last summer.
 
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