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Old 09-04-2012, 11:17 AM   #1
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Default Symptoms of bad turbo seal

Over the last few days, I have been smelling burnt oil when I come to a stop or on start up after a hot shutdown. My wb o2s has also been acting up as well. If I hold the revs at 2-3k rpm when stopped, after about 10 seconds blue smoke start billowing out of my exhaust. I am leaning towards a failing turbo seal since the engine is only 4k miles old and just passed compression and leakdown tests with flying colors. I also replaced valve guide seals when the engine was rebuilt.

Car still runs great with no noticable power loss as of yet. Turbo is a begi/churbo 2854 with about 10k miles on it.
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Old 09-04-2012, 11:37 AM   #2
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fix you drain line issue.
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Old 09-04-2012, 12:28 PM   #3
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I will check it when I get home! thx Brainy U think it's clogged or something?
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Old 09-04-2012, 12:29 PM   #4
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if you fix whatever is causing the pressure differential to be out of balance, sure.
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Old 09-05-2012, 06:44 PM   #5
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Well, I ended up working late last night and didn't have time for the miata besides taking a quick glance at the return hose. It still appears to be in the same condition as it's always been, no kinks or bends that I can see. I am going to cut it off and replace it tonight because it's cheap and easy so I will report back tomorrow with results.

As some of you may know, I recently upgraded my exhaust from stock to full 3" no cat/res. I am wondering if that perhaps had anything to do with my sudden smoking issue? Less backpressure maybe causing a pressure diff?

idk, just throwing it out there.
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Old 09-05-2012, 08:50 PM   #6
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Ok, replaced the hose and noticed no difference in the smoking issue that develops once you hold the revs at 2k for about 10 seconds. The old hose had no restrictions inside, it was clean all the way to the pan. The new one I just installed has an even better angle/flow than previously.

For ***** and giggles I pulled all the spark plugs and they all look the same with no signs of oil deposits, same with the tops of the pistons.

So....compression test 185psi (all), leakdown test 5% or less @100psi line pressure (all), plugs good, new return line didn't fix it. Is it safe to say the turbo is taking a **** on me? The only thing left to do is pull the dp and see if there is a bunch of oil in there I guess?
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Old 09-16-2012, 02:41 AM   #7
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Still unlikely that it is the turbo. Despite how often you hear about supposedly bad seals, it is extremely rare for them to actually be bad. It takes a pretty significant overheat of the turbo to collapse the piston ring style seals used on most turbos.

Braineack's comments are still on the money. If its burning oil, your drain line isn't working well enough.
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Old 09-16-2012, 01:30 PM   #8
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The charge piping is dry as can be, no evidence of oil coming from that side.

With a journal bearing turbo, would it be wise to try a restrictor in the feed line? Would that even help? My drain hose is 1/2" and has a great angle. I had the drain flange and fitting off of the turbo too and every looks perfect, I even got a good look into the chra and it shows no evidence of any carbon/coke build up.

I guess what I'm asking is why all of a sudden is this happening? I've had the same hotside setup for 3 years without issue. The only thing that changed recently was the exhaust and boost level (11 v. 15)

The engine feels beast. No power loss at all.

Last edited by flounder; 09-16-2012 at 04:11 PM.
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Old 09-17-2012, 05:00 PM   #9
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1/2" inside or outside diameter?

most people use -10an which is 3/4" id.
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Old 09-22-2012, 03:42 PM   #10
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It's 1/2" ID. It's the same one that came with the shanghai kit for the 2854 churbo. I never had any issues with it before.

Is it possible the exhaust is creating an issue? Anyone ever hear of that happening after a 3" straight through goes on?
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Old 09-22-2012, 04:02 PM   #11
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do you have -3an or -4an line?

do you have a catch can?
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Old 09-23-2012, 12:05 PM   #12
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Make sure you haven't done anything that can allow the crankcase to pressurize at all. If you have a PCV system on the car, make sure it is working well, or if you are just venting, make sure it is venting well (prefereably through a catch can or filter). Pressure being driven back up into the turbo through the drain line can cause oil to move past the seals as well.

I'd also step up to a larger drain line. There is a reason -10 AN lines are common for this... make sure the path for the line is as smooth and straight as possible and always angled down through the whole run. The more veritcal the better.

I'm always hesitant to tell people to restrict oil flow to a turbo, because it is extremely hard to judge if you're getting "enough" at any given time. OEMs do long drawn out oil surveys to ensure proper oil flow, and turbo manufacturers have a long list of how much oil the turbo needs under all sorts of different conditions. That said, it is possible you are feeding too much oil volume for your drain to keep up with. Fix the drain first though, before you consider reducing oil feed (unless you are running a ton of oil in...) when in doubt, copy those that have had good success. ie, back to Braineack's comments, lol.
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Old 09-23-2012, 12:52 PM   #13
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I did some reading through the begi instructions for my turbo and it states that I have a 3/8" NPT fitting on both the turbo side and the pan side wth a 1/2" ID hose. So basically I think the fittings are too small. So...I need to find a different turbo drain flange/fitting, and re-tap my pan for a larger hole? What a pita!
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