losing oil?
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Senior User
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losing oil?
has anyone had this? Ive got an 86 351W that is losing oil by the quarts, but I cant find it. Ive got no external leaks that I can find, no oil in the radiator, and compression test comes up perfect. No smoke out the tail either. The only other info I have is that it was rebuilt a couple thousand miles ago. Can someone please help point me in the right direction to locate my oil. thank you.
Post Fiend
Joined: Nov 2002
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From: Memphis, TN
losing oil?
Does it only lose it while you're driving? You don't see any on the ground where you park? Clean the underside of the truck THOROUGHLY with Gunk Engine Brite (or equivalent) & a high-pressure spray (like any self-service car wash) so you can see what's fresh.
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Joined: Dec 2002
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From: weaverville USA
losing oil?
Were the heads rebuilt during the rebuild? My 86' 302, had similar oil disappearance problems. I was going through about a quart every 200 to 300 miles. I never really noticed any smoke, except upon start up. As it turned out the heads had leaky valve guides and apparantly all my oil was disappearing during combustion or whatever. A local machanic told me that leaky valve guides are rather common with "older" 302's. Just a thought.
Eric
Eric
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Joined: Jun 2001
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From: Loveland, CO.
losing oil?
I had a Camaro once that leaked oil from the rear main seal only when the engine was running. I couldn't see any oil on the motor, and it did not leave puddles under the car. But one day I happened to look at it while it was running, and there was a consistent drip-drip-drip from the rear main seal.
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losing oil?
I have to correct myself in saying that there is no exhaust smoke. I thought I caught sight of it the other day so I set my side mirror to the tailpipe, When I floored it she bellowed out all kinds of smoke. As soon as I would let up it was gone. Mash her down again and there it is. Hard to say what color the smoke is. Not white. Kind of black brownish. Ill check again. mabey drive behind her to see for sure. The engines got 8000 miles on it. As far as I know bottom redone. Valve job. same intake. Like I said compression perfect and loosing tons of oil. Can someone advise to troubleshoot oil/smoke problem. Related or seperate?
Elder User
Joined: Apr 2002
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From: NJ
losing oil?
if you smoke on acceleration it is usually the rings. if you smoke when you let off of the gas and then puff smoke when you hit the gas its usually valve guides or valve guide seals.how much oil did you say you were losing in how many miles?
Elder User
Joined: Apr 2002
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From: NJ
losing oil?
you could still have a bad oil ring and there would not be any loss of compression. dont know how to tell if the oil ring is bad but back in the late 70's my friend had a broken oil scraper ring on just one cylender and the engine really smoked bad . if i remember corroctly it was about a quart in 75 miles. but you would definetly see major smoke.
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Joined: Aug 2002
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From: Madison USA
losing oil?
well, if the intake is in similar design to the dodge 3.9L, 5.2L, 5.9L engines, and has a pan on the bottom of it from manufacture, that pan gasket on the bottom of the intake leaks, and then oil is sucked up into the intake. smoke only is made when you mash the throttle and oil actually get sucked into the motor, and it can be many quarts in a short time, i've seen a lot of those motors run out of oil in under 2000 miles and seize up. compression is fine, no visible leaks, etc, but have you checked vacuum? when the pan gasket leaks, it is a vacuum leak right into the lifter galley
