Oill pressure off the chart

brianpharmd

brianpharmd

Senior Member
My car came with an Rex-A-Co oil pressure gauge (0-10 reading). From the prior threads (2016-2014), I have read that oil pressure might be 3-5 when cold and 0 to nearly 0 when warm. However, my car is ******* the oil pressure gauge well beyond the 10 especially at higher speeds. At idle, pressure is around 2 but as I accelerate, the pressures increase to where they stop since the needle can't go up any further. Obviously I am building pressure in the engine, according to previous threads, is something that should have little to no pressure at all times. I can't find in any threads that I search with criteria "oil pressure" or "oil pressure gauge" any mention of overtly high readings. Most threads just talk about readings of 0 or people not installing/hooking up the gauge.

Any ideas on what I should be checking to eliminate the pressure? The car does not have the standard oil filler tube. It has a tube that allows blow by to be vented out of the engine and under the car. Should I prop open the lid to the oil filler tube and drive with it open to see if that adjusts the pressure reading? I have a rear main leak and I figure the pressure in the system is not helping it since that is the point of least resistance.

Thanks,

Brian
 
Propping open the "lid" on the oil filler would only serve to splatter oil all over the side of your engine.
 
CarlG said:
Propping open the "lid" on the oil filler would only serve to splatter oil all over the side of your engine.
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And that would put his pressure up, blood pressure That is, when he saw the mess to clean up! Wayne

P.s. My dad used to say when you get an unbelievable reading, check the gauge!
 
CarlG said:
Propping open the "lid" on the oil filler would only serve to splatter oil all over the side of your engine.
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Carl -

That was my thought but it was a recommendation per the antique engine rebuilding site that I have seen frequently linked by seasoned posters on how to diagnose a rear main leak.

http://www.antiqueenginerebuilding.com/REARMAINLEAK.html

"2. Remove oil filler cap check to see that oil filler pipe is not restricted or plugged. With oil filler cap removed from car take car for a drive. If leak stopped the oil filler cap is bad."
 
The oil filler tube should have nothing to do with the oil pressure in the engine as measured by the gauge. I wonder if someone modified your engine with a high pressure oil pump when it was rebuilt? Can you check with the rebuilder?

Charlie Stephens
 
You may have an upgraded oil pump installed in your engine. The Model A oil pump by itself delivers about 80 psi, along with a huge volume. I wouldn't try this at home, but if you need further evidence you might take a rebuilt pump, chuck it into a 1/2" drill and give it a spin in a pail of oil. Wear a rain suit.
The pump looses 90% of it's pressure and volume at the point of gearing in the block.
 
Charlie and Glenn -

I'll try and find out what I can about the rebuilt motor. The problem is this was a car purchased from the daughter who inherited the car about 4 years ago. They don't know much about the history of the car. I'm reaching out to a couple of my club members who helped the father that owned the car back in the day to see if they know much about the motor. I know it has a high compression head. Let me see if I can find out any additional information. Just seems odd to put an oil pressure gauge on a car if it had an upgraded oil pump since the readings would not correlate.

Brian
 
brianpharmd said:
Charlie and Glenn -

I'll try and find out what I can about the rebuilt motor. The problem is this was a car purchased from the daughter who inherited the car about 4 years ago. They don't know much about the history of the car. I'm reaching out to a couple of my club members who helped the father that owned the car back in the day to see if they know much about the motor. I know it has a high compression head. Let me see if I can find out any additional information. Just seems odd to put an oil pressure gauge on a car if it had an upgraded oil pump since the readings would not correlate.

Brian
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Does it have insert bearings? Sometimes they upgrade the pump when they go to insert bearings.

Charlie Stephens
 
I have an old Ampco guage in one of mine that pegs when I start it.I hooked up a newer guage in it's place,and got 2-3 pounds of pressure.I don't know how old your guage is,but mine is just old junk and is in there for looks.
 
Charlie -

Here are some pictures that I took when I had the oil pan off a few weeks ago. I don't know if you can tell if these are inserts or babbitt. I plan to have a couple guys from my club help me next month or so measure all of the clearances so I have a baseline.

Would a special oil pump if this car has it causethe motor to be pressurized? I guess I am just not familiar with this concept. If it is somehow pressurized, do I just do the same checks for rear main clearance and end crank play to ensure the rear main doesn't leak? Just trying then to figure out how to keep what I believe is a normal rear main setup from leaking if it was not normally but for a pressurized system.

Brian
 

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You would have extra oil lines running around in there if it was a pressurized motor and no dippers on the rods. It appears as you still have a splash motor.
 
So this motor does not look any different from what I can tell inside the block than the engine in my 30 coupe. So have we ruled out the pressurized motor and different oil pump? Or could I still have a different oil pump? If we have ruled both out then what other options are there for the pressure? I did see mentioned a defective gauge but the gauge is a zero when the engine is off and moves incrementally up as speed increases. I would think that the guage would not respond incrementally or would not be at zero with the engine off if the calibration was incorrect.

I'm typing on a cell phone so I apologize for spelling/sentence structure issues.

Brian
 
Ron W said:
What weight oil are you using? Ron W
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Castrol 10W30. Also, car has oil filter that mounts to the side, not at an angle. Forgot about that. I included a picture of the oil filter in case that is an issue. The oil filter is a NAPA one that I purchased from website just so I had the correct one/size.

Brian
 

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I would remove the side cover for the valves, and check to see if you have full open flow out the front end of the oil tube. If it's original and open, then your gauge must be wrong.

OK, the filter is the answer. The oil pressure build enough pressure to overcome the check valve in the filter, plus the filter itself offers some resistance.
 
Tom Wesenberg said:
I would remove the side cover for the valves, and check to see if you have full open flow out the front end of the oil tube. If it's original and open, then your gauge must be wrong.

OK, the filter is the answer. The oil pressure build enough pressure to overcome the check valve in the filter, plus the filter itself offers some resistance.
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Tom -

Then the gauge is designed for a non oil filter system? If so, then my readings are not off the mark? With the filter and extra pressure it creates, what additional concerns should I have about the leak out the rear main? Should ensuring the rear main clearance is within tolerance and checking crank end play suffice? Or am I going to be set up for a premature failure at the rear main?
 
Adding a filter will increase the oil pressure as measured at the port, but will have no effect on the rear main leaking, nor the pressure to the mains and rods.
 
brianpharmd said:
Tom -

Then the gauge is designed for a non oil filter system? If so, then my readings are not off the mark? With the filter and extra pressure it creates, what additional concerns should I have about the leak out the rear main? Should ensuring the rear main clearance is within tolerance and checking crank end play suffice? Or am I going to be set up for a premature failure at the rear main?
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See my dads advice in post number 3. Wayne
 
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