5.4 Using Oil
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Freshman User
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5.4 Using Oil
My 2000 5.4 has started using about 2-3 quarts of oil between oil changes. I haven't really gotten inside a mod motor yet to see where the wear occurs most. In your experience is it the valve seals or the cylinders that wear out first. I found a deal on a used 5.4 with about 15000 miles on it that I'm trying so swing a deal on. Once I put that motor in then I can rebuild this one with a little more power.
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I just tore down a '94 4.6 that my daughter-in-law ran low of oil and ruined the heads. The left bank cam siezed up, the sprocket bolt twisted off, the loose sprocket knocked the cam sensor through the front cover, the right cam was just before siezing....you can imagine the damage.
On the tear-down it looked the oil had been leaking through the front seal but what surprised me was there was very little wear in the cylinders. Ring travel was negligible and you could still see some of the original cross-hatching on the cylinder walls. I haven't miked the crank journals but the bearings still looked to be in good shape.....go figure. This is on a 148 K mile engine owned by someone who never checked or changed the oil.
Good luck on your engine project.
On the tear-down it looked the oil had been leaking through the front seal but what surprised me was there was very little wear in the cylinders. Ring travel was negligible and you could still see some of the original cross-hatching on the cylinder walls. I haven't miked the crank journals but the bearings still looked to be in good shape.....go figure. This is on a 148 K mile engine owned by someone who never checked or changed the oil.
Good luck on your engine project.
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A PCV valve can suck oil through an engine because it uses engine vacuum to to suck combustion gases back into the intake to be burned in the engine (thus lowere emissions by not venting these gases to the atmosphere.) Over time these valves get old and clogged and if not replaced at the proper service intervals, PCV valves have been known to suck oil up from the under the valve cover where they're located and spit it into the intake. If this is the case though especially using oil at that rate you would see LARGE amounts of oil in the air cleaner and snorkel. Also check for lecking pan gaskets and other engine seals. If it doesn't appear that you're burning oil in anyway then it's more likely on of those. A rear main seal can cause serious oil leakage and be hard spot at first because of the fact that it's covered by the transmission. Hope this helps/
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From: Brunswick, Maryland
The pcv valve is relieving crankcase pressure when it is working properly. If it clogs up it quits relieving that pressure and it surely can't be sucking oil out the engine because it is clogged up. The engine oil could get into the intake through the breather ( which is separate from the pcv valve) because excessive crankcase pressure is forcing oil into the intake system as a direct result of a clogged pcv valve.
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you are correct about this, but a partially clogged PCV valve can cause the same thing. also, you have to keep in mind that a PCV system generally has two paths: The path that vents the combustion gases to the intake and that path that provides fresh air from the intake. Built up pressure in the crankcase can and will force oil through the fresh air side or even the partially clogged vent side. Also, the difference in pressure between the intake which is generally going to be from 0psi to some level of vacuum depending on operating conditions, and the pressurised crankcase will cause oil to be sucked up through the system and into the intake. I didn't make myself clear enough in the original post and I appologize for that.
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pcguy760
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Feb 26, 2006 10:39 PM
