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I've got an 01 accent with 123k miles on it. Its gradually burnt oil more and more since I got it with 28,000 miles on it. At this point it seems to have good compression(all cylinders are between 205 and 215 psi), but the blue cloud of doom follows me everywhere (especially when I idle at a light somewhere for a few minutes) and I'm running 10w 40 in it. I've tried using some oil additives that are supposed to rejuvenate worn rings and seals, but it only works for about 600 miles before im back to burning the same amount of oil.

I really haven't had to put much money into this car, so I'm considering buying a motor from a junkyard and having it put in. Here in NJ I can get one with less than 100k on it for about $250. Does anybody know about how much labor would cost to do the install or if this seems like a worthwhile endeavor? Thanks!
 

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You are leaking oil through your intake valve seals.

I am having the same issue with my 1.5L 2001 accent with about the same mileage.

If your car is running fine, still has power, still has economy, and is simply burning lots of oil, all you need to do is have the valve seals replaced. This is a complex task but you may be able to do it on your own without even having to remove the cylinder head. I estimate that taking the car to a mechanic to have the intake seals replaced might still be the best option for you.

You would have to remove the valve cover, timing belt, camshaft, and rockers. Then you would have to use air or a rope inside the cylinder to seat the valve in the closed position. Then you will need a tool to remove the valve spring. Then you change out the seal. Repeat for all intake valves.

If you are curious why it is burning so much oil when it is idling, here is the science behind it.

Under your valve cover you have a cam, lifters, and the top of your valve stems that need lubrication. They are saturated with oil and are at crankcase pressure. On a "standard day" that would be approx 29.9 In. Hg. (15 PSI absolute) The valve stem then passes through a seal to keep the oil out of the intake port and then a guide to keep the valve in proper alignment. Underneath the guide, you have the intake port. At idle, there would be at about 24-28 in. hg of vacuum on the manifold and in the intake port. This would be the pressure differential between the two.

That leaves 12-14 psi trying to force oil down the valve seals and through the valve guides into the intake ports where it will be ingested into the combustion chamber when the valve opens. When your foot is on the pedal, the manifold pressure is much less, and thus there is much less pressure differential trying to force oil down the intake valve seals.

The exhaust ports have exhaust back-pressure which would try to force itself upward and keep oil out of the exhaust ports. This is why they are not as prone to leaking oil into the combustion chamber. Also they get very hot and oil will "coke" up on the valve stem, minimizing any clearance in the guide also reducing any oil leaking into the combustion chamber.

Hope this helps.
 
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