LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Oil consumtion causes

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Old Sep 16, 2003 | 11:45 PM
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Oil consumtion causes

I know I have a small leak in my oil pan gasket, but I just went thru about a quart of oil in 300 miles I also know I have leaky valve seals. But I refuse to accept the fact that my piston rings are shot. Is there any other reason that I could go thru a quart of oil in 300 miles besides bad piston rings?
Old Sep 16, 2003 | 11:51 PM
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Have you pulled the plugs? If so, are they coated in oil? Does white smoke come out of the tailpipes when cruising or at WOT. Another cause other than the ones you listed could be a blown head gasket? Have you done a compression test? Is there a noticeable puddle of oil under the car where the oil pan gasket leak is?
Old Sep 16, 2003 | 11:58 PM
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No unfortuantly the oil pan gasket leak is small, and only a small amount trickles out, no way that could account for more than 1/8th of a quart over the last 2 weeks. I dont know about the smoke coming out of the car whlie crusing, but it does smoke a bit for 30 seconds after startup due to the valve seals. Im going to check my PCV valve tomorrow to see if that could be a reason for anything, But I wount get to pull the plugs untill later this week due to school and work. I doubt the head gasket is blown thou because my oil isnt discolored, or at least I dont think so. I just hope its anything besides my rings because that would be the biggest PITA.
Old Sep 16, 2003 | 11:59 PM
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How many miles are on your motor?
Old Sep 17, 2003 | 12:35 AM
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Between 6-10k since the rebuild. I forget the exact mileage and cannot check this moment because Im in the middle of putting a new computer together, so Im stuck with my parents, and have all the files on mine :/
Also I think it started leaking oil more after I overheated once, my waterpump seal broke and started leaking water out the weep hole badly, got no low water idiot light, and by time I noticed the water temp above normal and shut off the car I was pretty far in the red... Never pay more attention to your passengers than your gauges

Last edited by m0nk; Sep 17, 2003 at 12:37 AM.
Old Sep 17, 2003 | 01:22 AM
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well frist off, you have forged pistions and they take a little more time to heat up and expand thus low motor temp oil consumption will be highe ( just look at Ford's 85-92 mustang oil consumption is 1qt for 1000 miles and they consider the excptible)

but even still there may be excessive valve to guide clearence and that would cause massive oil consumption.

I would do a leak down test and if all are with in spec, i would suspect the guides
Old Sep 17, 2003 | 01:23 AM
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I know the forged pistons account for a bit of it, along with the valve seals, and small oilpan leak, but I cant see all that accounting for 1 qt/ 300 miles
Old Sep 17, 2003 | 01:34 AM
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well its not just the seals, if the guides are worn they will let a lot of oil by even if the seals are good. When heads are re-done some times people will skip the guide replacement to cut down on cost.
Old Nov 8, 2003 | 06:21 PM
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I finally did a compression check, I let the engine idle for about 5-10 minutes and the temp was at ~165* when I shut her off. 160PSI on all cylenders except the #3@ 150. So I doubt my oil comsumption is due to bad piston rings, unless they are all bad :/ So I figure I has to be the valve seals, but would that cause the exhaust to have a blue hue? I thought only a little smoke after startup was attributed to leaking valve seals.
Old Dec 21, 2003 | 11:55 PM
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It could be the cylinder walls out of round due to you running it hot also....
Old Dec 22, 2003 | 01:22 AM
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When you overheated the engine the rings overheat too. They can lose most of their designed-in tension, and relax, and that can cause the oil consumption. It is also possible that you scuffed the cylinder walls a bit, but that would normally show up in the compression test. Which looks a little low anyways, assuming the gauge is accurate.
Old Dec 22, 2003 | 02:41 AM
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These numbers were taken with a brand new compression tester. I assumed they were low due to my low compression 8.3:1. Also the fact that 7 were exactly the same and 1 was 10 psi off that they were all within acceptable range. I always assumed that when I overheadted the engine I messed up the rings untill this test was conducted. So unless this test was wrong that rules out the rings and the walls. correct?
Old Dec 22, 2003 | 10:47 AM
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Those numbers sound good for the compression ratio you have, and they are even. Nonetheless, loss of ring tension will cause oil burning and can still show acceptable compression during cranking. If all cylinders show even spark plug colour, then all are burning oil, and that leads back to rings.
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