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Old Sep 25, 2006 | 03:42 PM
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Odd oil pressure issue

Hey all. I've got a '79 LTD with a 351w in it. It seems that I'm losing oil pressure when hot in gear at idle. This has been verified with a gauge. I have 65psi cold in park, and ~15 in gear after about five minutes of warm up time. I used some 5w30 (what I had, I live in the sticks) in it when it was low the last time. I noticed that I no longer get that annoying ENGINE light flicker. It was low again here recently so again I put 5w30 in it. First time out it did act like it was getting worse, but then just like before it's stopped almost completely.
 
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Old Sep 25, 2006 | 04:08 PM
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that oil is to light. run some 20w30 in there or even some 10-40 it will help the oil pressure for sure. the 5w30 is meant for newer motors with much tighter clearances
 
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Old Sep 25, 2006 | 04:16 PM
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The 10w40, and 15w140 make the problem worse. IE knocking motor. The 5w30 clears it up.
 
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Old Sep 26, 2006 | 09:54 AM
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then you have a blockage some place, the pickup tube maybe to close to the pan. what oil filter brand are you running? your running regular dyno oil as well right not synthetic?
 
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Old Sep 26, 2006 | 08:22 PM
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Running a Motorcraft FL1A filter, and whatever oil I can get for less than $2. Usually NAPA oil. As far as I know the engine has never been apart. It's got roughly 165k miles on it. Between the front seal, and the dipstick tube leaking at the pan, it's losing about a quart every week and a half to two weeks.
 
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Old Sep 27, 2006 | 09:32 AM
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this is strange, usually the thicker oil will increase pressure and remove the knocking but yours is doing the opposite. You might try some seafoam or just continue to run the 5w oil. might do a compression test. how do the plugs look and is the pcv valve new?
 
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Old Sep 27, 2006 | 09:13 PM
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The PCV is not new, but it's working fine. The drivers side bank of pistons has blowby like you wouldn't believe, the passenger side is pretty good for as many miles as are on it. The plugs are a tan color, the number 5 plug (front drivers side) was a pretty tan-white color. They aren't very old IIRC. I'll know more about what it's doing tomorrow when I get my oil pressure gauge hooked up. The temp runs 195 to 200 degrees. The only time it ever gets any higher than that is the first warm up before the thermostat opens the first time. Then it goes up to 215 and falls right back down to 195.
 
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Old Sep 28, 2006 | 09:30 AM
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well get that gauge hooked up and let us know what you find. something is weird
 
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Old Sep 28, 2006 | 10:18 AM
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Sounds like the old worn bearings/excessive clearance problem to me. Time for a rebuild.
 
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Old Sep 28, 2006 | 11:45 AM
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With pretty fresh 5w30 but a ~6 month old NAPA filter I had 50psi cold idle in park, had less than 10 hot idle in park. With a fresh FL1-A filter and 15w40 Super Tech oil, I have ~20psi hot idle in park, and I've not seen it lower than 10psi in gear. Even with it idling like crap. Anyone have a spare 2150 carb in good shape the want to sell cheap?
 
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Old Sep 29, 2006 | 05:21 AM
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This is good to read we can even help Ford cars...nice work guys.
 
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