So my 95 ST had a rod knock and was burning oil so I figured I'd do a full rebuild. I replaced the pistons, rod and main bearings, and new rings. The the engine was over-bored to .50mm and the crank to .25 over-bore, which called for bigger pistons and bearings. I followed Smaay's rebuild thread. Everything looked good. So once the rebuild was done I cranked the motor and it turned on very quickly. And for the first 700 miles I noticed the oil level wasn't changing so I thought it wasn't burning any more oil. But then when it was at 1,200 I checked the dipstick and it was missing about a quart. I've changed the pcv valve and its still burning oil. I opened up the intake manifold cover and its full of oil. I don't know what else to do. I'm thinking Im gonna have to throw away a lot of money and just get rid of this motor and get a used one that will hopefully not burn any oil. Anyone have any suggestions as to what I should do? Car runs perfectly fine, its just that it burns oil. I did a compression test and it reads a little over 160 on all cylinders. No leak down test has been done yet.

This post has been edited by metaldude19: May 17, 2012 - 11:30 AM

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Valve stem seals?

Sounds like the head needs rebuilt now too

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I forgot to mention, head is fully rebuilt too. New valve seals and valves were sandblasted. its a fully rebuilt motor. Somehow the oil is getting from the valve cover into the intake manifold.

Hmm
Is it maybe getting pulled into the intake through the valve cover breather hose?

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That's what I'm thinking. There's another hose right next to the hose with the pcv valve that might be sucking up some oil, but I'm not too sure.

Id start her up an pull the hose off an see is any oil comes out

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Yeah I'm gonna do that today. Would it be a big deal if I were to plug that hose up?

Yes
Atleast one of those is a breather for the valve cover
An you have to have that vented to make sure you dont get to much pressure builtup under the vc
might want to change out the pcv valve again
New doesnt always mean good

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I've changed it twice already. So I don't know what else to check. This thing is pissing me off.

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You NEED the pcv, not only releases pressure(i removed mine for a month, oil pan started leaking), but it actually helps keep your oil clean by venting out the little bit of gas the gets by the rings and water the can build up over time.

Pull the breather hose off while the engine is running, with the one end still attached to the valve cover. Place your thumb over the open end of the hose and blip the throttle. Is it pulling any kind of vacuum?

hhmmm sounds like you did everything right. my first guess would be the PCV, is it possible you have the hose routing wrong and still pressurizing the crankcase?

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I did everything from a full head rebuilt along with the bottom end. I'm bot home right now so I can't check my car, but I took several pictures of all the hoses and made sure I put them back exactly how they went. Im almost to the point of saying screw it and just buying another motor. But that's a lot of money going to waste.

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I'll go ahead and check it out tomorrow morning and keep you guys updated on what's going on.

its possible the rings were installed upside down (theyre beveled to scrape oil off, and if its backwards itll let ALOT of oil through)

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Also if the ring gaps are lined up itll let some through. gotta make sure there all at different sides of the piston.

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I made sure all the "up" sides were pointing up, and that none of the gaps lined up.

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Which hose would be routed wrong to where its pressuring the crankcase?

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Piston rings spin. However you installed is not the way they will stay. In fact, the manual calls for you to install them all facing a certain direction doesnt it?