Oil burning/disappearing after engine rebuild - Subaru Outback - Subaru Outback Forums
 
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post #1 of 8 (permalink) Old 05-16-2013, 11:16 AM Thread Starter
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Oil burning/disappearing after engine rebuild

Hello everyone!

I am in a bit of a pickle. About 1 year ago I rebuilt the engine in my 98 OBW - from the head gaskets up. Visually - everything looked healthy in the bottom end.

The head's where decked, new gaskets, and LITERALLY all oil seals were replaced...

That brings me to the issue. Oil is literally disappearing... the exterior of the engine is bone dry - no oil slick under the car. This leads be to believe that it's burning it, but exhaust doesn't seem to be thick plumes of smoke/etc... However it has developed a tick at random RPM's, depending on the level of oil of course.

I run 10w40 in it, just so it doesn't consume oil so quickly - but the oil light comes on at least once a week, and buying the jugs of oil to carry around is getting old.

Basically - I am looking for opinions/advice. What should I do? Rebuild? Again? New engine? Sell the car as-is and move on?

Other points, perhaps to sway you. The center diff was loose when I purchased the car. I know that is an widely seen issue with these. I spun either side of the carrier in little by little until there was no slack, I don't really think there was another option, besides rebuild/replace... Which was out of my budget at the time.

So, We have a car that looses oil, ticks, and has a transmission that could potentially go at any time.

I appreciate your opinions and time. Thank you!
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post #2 of 8 (permalink) Old 05-16-2013, 11:34 AM
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You could have some stuck oil rings. When you rebuilt the engine did you do any cleaning of the pistons? Did you let carbon and old head gasket material possibly get mixed in with the rings.

I have a similar issue after redoing the heads on my H6. When I made a change to Mobil 1 Extended Performance I saw a dramatic drop in oil use. Possibly one of the stuck rings got unstuck (?). My oil use is pretty manageable though. < Quart per 1000 miles.

I am thinking about doing a flush with Auto-Rx though. I don't think it can hurt.

How fast are you losing oil?
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post #3 of 8 (permalink) Old 05-16-2013, 11:41 AM
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double check placement/routing of the PCV and breather hoses.

Read a thread once that led to those hoses being mixed up. It caused some weird symptoms including oil usage, 'gurgling' noise in the oil dipstick tube, etc.

Pull the plugs. If one looks different from the other 3, maybe stuck ring as mentioned above?

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post #4 of 8 (permalink) Old 05-16-2013, 11:48 AM Thread Starter
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When the heads where off I cleaned the deck and the cylinder walls as best as I could. I made sure there was no remnants of carbon before putting the heads back on.

Pulling the plugs is a good idea - it should at least point me in the right direction.

It really seems like the car just doesn't have any power - I mean I get it's only a little 4 banger - but accelerating up a hill seems like a real chore...

It's entirely possible it was far worse off than I thought when I bought it. It was somewhat sight-unseen. Literally picked it up, drove it home, and pulled the engine out in a weekend.

Thank you for the input - keep it coming! I appreciate it!
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post #5 of 8 (permalink) Old 05-16-2013, 11:57 AM
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oil tends to lower octane rating of the combustion charge which could lead to knock and the ECU changing the timing. That might lead to a little loss of power, but, I also wonder if your timing could be a tooth off. maybe, if some of the easier checks don't pan out, pull the timing cover and double check the timing?

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post #6 of 8 (permalink) Old 05-16-2013, 12:35 PM
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Does your tail pipe have a dark ring around it at the end? If so you are burning oil. The statement about the PVC valve could be the answer
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post #7 of 8 (permalink) Old 05-16-2013, 06:15 PM
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And with 2 cats in series, the cats could be catching the carbon. Which will lead to a clogged and non functioning catalytic converter.
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post #8 of 8 (permalink) Old 05-17-2013, 02:53 PM Thread Starter
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The timing assembly (belts, tensioner, idlers) was replaced during the rebuild. As well as many other maintenance parts. All direct OEM replacements.

I seem to remember the PCV being fairly straight forward, yet it has been a year since looking at it... Again, I will double check my work.

The check engine light did come on a few months ago. It was a bad rear O2 sensor, which has sense been replaced. I assumed it was due to burning oil but actually it was physical damage (not sure how that happened )

Yes. The exhaust does have black around it - though I figured this could be due to the O2 being faulty and running rich.

Again. Thank you all for your comments.
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