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High Oil Pressure


kenmatthews

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ENGINE: 322 V8 (rebuilt)

I just had my engine rebuilt and it runs pretty good now that I have adjusted hte carb, but I notice a reading of high oil pressure when driving. If idle or just starting up, the pressure is somewhere between just below "N" to normal. BUt as soon as I accelerate, the needle heads over to H.

What would this be an indication of, assuming the gauge works properly?

KEN

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Hi Ken

Not worry!

Sounds like it is working like it is supposed to. All of mine run above the normal range to nearly pegged high when up to speed with cold oil and runs at the upper limits of the normal range with hot oil. Then drops to mid to low normal when idling. You have to drive nearly 20 miles to get that 6 qt of oil hot.

Willie

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it means you got your money worth!

my straight -8, 1950 buick idels at in the medium range, and pegs the high side, when you race the engine.

That high pressure means tight main bearings.

My '50 engine was rebuilt four years ago.

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Whew...well that's a relief. Another bit of info to go along with this is I get a response from the engine at higher RPMs, usually beyond about 45-50mph. Engine will hum at me and I can feel vibration through the steering wheel. This is not to be confused with a PS issue. There are no PS leaks, and I only get the noise when I accelerate or have foot constantly on the accelerator. Does not happen at idle or when coasting.

Two things come to mind. Either the engine has not been broken in yet at the high speeds or there is no coolant running through the manifolds/block. I ran the engine with radiator cap off and didn't see the coolant moving at all. Will it only start flowing once the engine is warmed up or should it flow right away?

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ken

your thinking to much...

if you had no water flow, you could not drive the car down the street without if blowing steam.

the t-stat will hold the water in the block until it reaches 180 degrees.

All is well, don't forget to change the oil after 500 break in miles.

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Ken: The oil pressure is fine. Consider yourself lucky as others have low oil pressure and this is a major worry.

As far as the coolant is concerned, remember that the thermostat does not open until the car has warmed up. When the thermostat opens it allows water to enter the radiator and be cooled for return to the water jackets. Nevertheless, before the car warms up water circulates into the water jackets in the head and block through a bypass in front of the thermostat which prevents hot spots developing in the water jackets. This is why you can get heat out of the heater before the thermostat opens as the water going through the bypass also circulates to the heater and defroster. Look in your shop manual and this should be shown and explained. These are good questions and we are always learning. Patrick W. Brooks

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Ken, for good measure, you might get a manual oil pressure gauge and screw it into the block to see what the real oil pressure is at idle so you have a general idea of what the "normal" area of the car's gauge might be.

Did the machine shop possibly shim the relief spring in the oil pump when they did the work, possibly? A stiffer spring will usually result in higher oil pressure, or a softer spring that is shimmed can do pretty much the same thing, at all rpm levels. Higher pressure might take a few extra horsepower to run the oil pump, but as mentioned, it's better than not enough oil pressure.

Enjoy!

NTX5467

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Hey Ken

The hum and vibration can come from the engine but is more likely to come from accessories or the rest of the drive train (transmission, drive shaft, rear). Your can eliminate the accessories by removing the belt to that one and running the engine briefly. Some hum is normal for a Buick and the vibration could also be normal but is noticed because bad engine mounts allow it to transmit to the rest of the car. Some times even new mounts will make it more noticeable because they are harder than the originals.

Drive and enjoy!

Willie

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