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1990 Ford Mustang 5.0 Loss of Oil Pressure when accelerating

Old 04-22-2019, 03:06 PM
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MUSTANG5L
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Default 1990 Ford Mustang 5.0 Loss of Oil Pressure when accelerating

Hi there

Iíve recently rebuild my 90 mustang 5.0. Was a 302 and was bored 30 over. Primed the oil pump before start up and put about 30 miles on the engine and then noticed my oil pressure gauge kept dropping to zero when I accelerated and on decel and idle it came back up. Brought the vehicle home and noticed some noise from the valve train assuming the oils not getting there? I removed my distributor to look at the shaft and couldnít tell much. Now Iím wondering if I should run the car again with a gauge hooked up or if I should look towards dropping the oil pan and inspecting the oil pump? I replaced the pump with a normal oe spec melling pump and pick up tube.
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Old 04-22-2019, 03:33 PM
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drhoward
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I'd try checking by hooking up an aftermarket gauge just to be sure.
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Old 04-22-2019, 04:06 PM
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MUSTANG5L
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Okay I will do that first. I do have a fuel pressure gauge that measures 0-100psi. Would that work to test oil pressure aswell?
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Old 04-22-2019, 05:09 PM
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drhoward
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I'm honestly not sure if it will work or not, I had issues with mine a few years ago and I just bought a cheap gauge to check it. I think it was only around 20 dollars or something.
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Old 04-22-2019, 09:06 PM
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TrimDrip
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yeah, for sure check it with a mechanical gauge. they are pretty cheap at the parts store.

i guess the thrust bearing is good? I have seen that cause a loss of pressure on different type engines. I assume that may apply to the 5.0

is the car an auto or manual?

Last edited by TrimDrip; 04-22-2019 at 09:08 PM.
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Old 04-22-2019, 10:21 PM
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MUSTANG5L
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All the bearings were replaced when the motor was out. Car is a 5 speed manual. I will perform a oil change tomorrow and place a gauge and measure oil pressure
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Old 04-23-2019, 02:24 PM
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mjr46
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make sure you didn't blow an oil galley plug out.....there behind the timing cover.....right around where the cam slides in. that will cause the issue you describe. Had it happen more than once, now I tap those holes vs the press in plugs
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Old 04-23-2019, 07:46 PM
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MUSTANG5L
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Should I pull the timing cover out and inspect first?
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Old 04-24-2019, 10:52 PM
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Any guidance please? On if I should start by draining the oil and cutting open the filter to inspect and filling new oil and check pressure with a gauge or should I remove timing cover and inspect the oil gallery plug?
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Old 04-25-2019, 09:54 PM
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Anyway I can confirm I have a blown oil gallery plug without having to remove the timing cover?
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