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Ver. 5 STi excessive oil burning
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Old 04-22-2019, 11:29 AM   #1
Mintyy
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Default Ver. 5 STi excessive oil burning

In 2017 I did a full conversion of a MY00 2.5RS into a V5 STi using a half cut with less than 60k on the drivetrain. Car ran great for nearly a year, with some minor issues that where easily fixed. In May of last year, the car developed a very bad intermittent oil burning issue. All of this started after the car ran out of fuel one night. For the first few weeks after the car ran out of gas, all that could be noticed was a slight puff of smoke from the exhaust on startup. Eventually the smoke and oil consumption got so bad that there was a James Bond smoke screen whenever the car started up or was revved. The car was put out of commission after this and has been sitting ever since the issue became that bad.

Recently I wanted to try and identify the problem, so I can either fix it immediately or at least know for sure what I need to do. I started the car up and let it reach temperature. What puzzles me is how strong the motor still sounds. Idles smooth, has a rough startup due to oil burning, but I cannot hear any of the catastrophic engine damage from the block that is usually associated with this much oil being burnt.
I have attached a couple videos of the car at operating temperature to better detail what Iím talking about. The turbo was freshly rebuilt to fix the issue back in May, and it made no difference. I had a compression test done back in May as well, and I remember being surprised that the figures where as high as they were. No cylinders tested lower than 120psi, 1&2 testing around 150psi, 3&4 testing between 120-130psi. Could my issue be caused by something smaller that I am not considering?

My PCV system is a total hack job at best, and the car has had vacuum leaks here and there for its entire life. The turbo inlet pipe vacuum feed near the turbo was broken during an engine rebuild and was never fixed properly and is almost certainly leaking if functioning at all. Could a non-functioning PCV system be causing my issue?

As of right now, Iím leaning towards the problem possibly being a burnt / bent valve, PCV issues, or at worst, Ringland / cracked piston. Any opinions or help with this would be awesome, as the car has just been sitting for nearly a year.

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Old 04-23-2019, 07:37 AM   #2
silverton
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Compression test will only tell part of the story. the numbers are good, but a leak down test is what you need to have done.

For what it's worth, I just had another piston failure. 135psi on three cylinders, 60 on the dead one. Having a turbo really makes up for lack of a cylinder. As you say, other than a little smoke out the exhaust mine runs fine too! cracked ring lands will show up on a compression test, valve issues generally show up in leak down tests.
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Last edited by silverton; 04-23-2019 at 07:41 AM..
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Old 04-30-2019, 04:44 PM   #3
poormansporsche
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Yeah what silverton said. Really the only way to know.

Were you going full chat when you ran out of gas? I could see that causing a lean environment. Maybe that caused enough detonation to damage something in the lower end.

cheers

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