Oil Pressure Drop - Ford Muscle Forums : Ford Muscle Cars Tech Forum
 
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post #1 of 7 (permalink) Old 01-21-2002, 08:27 PM Thread Starter
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Oil Pressure Drop

'88 5.0 with ?? miles. Good oil pressure at start-up and when warm(around 50 psi at idle). Strange thing is that pressure drops once the rpm's pick-up. Rev. to 2000 and it drops to around 25 psi. Back to idle = back to 50 psi.

First time I've seen this problem. Guessing bad(or going bad) oil pump or something in the "line" thats messing up the sending unit.

Any ideas? I've got the motor out. Could replace the pump but there's original, high volume, and high pressure models available... Sooo many choices...



77 Cobra II 302 / 4spd. w/air
88 LX Conv. 5.0 conversion w/T5
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post #2 of 7 (permalink) Old 01-21-2002, 10:50 PM
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Oil Pressure Drop

Cobra,could be starving the oil pump for oil when revving if the oil is all pumped to the top of the motor and can't come down because of clogged head ports due to lack of oil changes concluding to SLUDGE buildup!!! At idle you won't have a problem!!!Check it out!!!Pull a valve cover and inspect before you do anything else!!!
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post #3 of 7 (permalink) Old 01-22-2002, 12:28 AM
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Oil Pressure Drop

Has anybody changed the oil pan or pickup.Make sure the pickup has enough clearance from the oil pan or it will cavitate and you'll lose pressure.Pan hasn't been dinged in by any chance?
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post #4 of 7 (permalink) Old 01-24-2002, 12:29 AM Thread Starter
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Oil Pressure Drop

Both worthy of checking... although I don't remember the pan being bent... Hope to get into it again next week.... Will let you know what I find. Thanks for the input!



77 Cobra II 302 / 4spd. w/air
88 LX Conv. 5.0 conversion w/T5
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post #5 of 7 (permalink) Old 01-25-2002, 10:01 PM
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Oil Pressure Drop

I had a 460 do that once, but it turned out to be a high volume oil pump combined with loose clearances at the cam, crank, and rod bearings, it was sucking the pan dry. Every time I've seen a 302 do it, it was due to the factory plastic cam gear coming apart and stopping up the oil pump pickup screen.
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post #6 of 7 (permalink) Old 01-25-2002, 10:43 PM
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Oil Pressure Drop

I couldn't tell by the original post. Is this gauge the factory electric or a manual?
If factory electric, Ford uses a voltage regulator at the back of the instrument panel. These commonly go bad and make the gauges do strange things. If its the factory gauge I'd check this first. Use a manual pressure gauge.
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post #7 of 7 (permalink) Old 02-02-2002, 01:12 AM Thread Starter
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Oil Pressure Drop

It's been a while, but I finally took the thing apart.... Clean as a whistle inside. No blockage in the returns. There is a small dent in the bottom of the oilpan(not more than 3/8" though). I'll pound it out just the same.

The rods are all marked, so it looks like the engine was apart at one time. The pick-up tube looks good(clean, E7 part number) and the bolts were all tight(no evidence of air leaks).

Oilpump is a Ford with a C2 number on it. Any suggestions on replacement (stock, hi pressure, hi volume)?

Point taken about the electrical switch.





77 Cobra II 302 / 4spd. w/air
88 LX Conv. 5.0 conversion w/T5
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