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Mystery oil leak

5765 Views 7 Replies 4 Participants Last post by  buckbo972
Hi all. I've just spent the past couple hours digging under the hood in search of a slow oil leak around the turbo with not good results, and I need some direction.

2005 FXT 5MT 170k miles. Turbo replaced by Subaru at ~92k miles.

Summary of symptoms: A year ago I began getting a faint oil burning odor, usually after some aggressive lead-foot. Fast forward one year and it's progressed. After about 10-15 mins of non-aggressive driving, I've got smoke rising from under the turbo. Under the motor there's oil seeping across the heat shields (pictured). Idling for 30 mins produces no smoke, only driving. The worst smoking lasts 5 or 10 mins and then slows down. There is no oil dripping on the ground, and oil consumption is just as it's always been.

The area under/adjacent to the uppipe is covered in oil. From the level of the spark plugs and down on the back of the block next to the turbo is wet with oil. My turbo oil supply line doesn't appear to be obviously cracked or leaking, but I can't say for sure that it's not.

After all now my noodle is exhausted and out of answers. I've searched for common oil leaks that would apply, but haven't come up with much more than the oil supply line cracking. Are there other possibilities I should give more attention to? Anyone ever have any luck with UV leak detector kits?

Any thoughts are very appreciated!


Pulled this heatshield and found more of the same--oil seeping from somewhere above the uppipe. Broke a wrench trying to begin pulling the uppipe and gave up.
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Removed the turbo oil supply hard line. No visible cracks in the line. I replaced it with the flexible, braided hose kit from P&L. No more leaks/burning oil. I'm assuming it was a leak the banjo fitting connection to the block.
I would check the valve cover gaskets. With 170k miles, if they have not been replaced, then they need it. My passenger side was leaking and it would smoke some out of the scoop and hood. Clean the whole area real good then go for a drive and see. The issue with some oil leaks like that is a little bit of oil will make it look like a huge leak. The best way to check the bottom of the valve cover is through the access door behind the passenger wheel where the O2 sensor is.
Link to the oil line kit you bought? Been thinking about doing this.
I would check the valve cover gaskets. With 170k miles, if they have not been replaced, then they need it. My passenger side was leaking and it would smoke some out of the scoop and hood. Clean the whole area real good then go for a drive and see. The issue with some oil leaks like that is a little bit of oil will make it look like a huge leak. The best way to check the bottom of the valve cover is through the access door behind the passenger wheel where the O2 sensor is.
Once I got everything broken down better and got a better mirror, I could clearly see an oil stain from where oil had been leaking down from the turbo oil supply line connection to the back of the block. But I've been thinking about the valve cover gaskets too.

I also tried to clean everything as well as I could, but it's a hell of a place to get clean. My best success was with a sprayer and some citrus degreaser that got about 90% of the oil off. Got any other ideas without taking too much apart?
Have you checked the oil pressure switch? I had a long-term intermittent oil leak like yours that I couldn't track down until the switch started spewing oil everywhere and it became obvious where it was coming from. If there's any oil on the top of the engine this is possibly your problem - an easy fix. There's a history with oil leaks on failing oil pressure sensors in Subaru's.
Have you checked the oil pressure switch? I had a long-term intermittent oil leak like yours that I couldn't track down until the switch started spewing oil everywhere and it became obvious where it was coming from. If there's any oil on the top of the engine this is possibly your problem - an easy fix. There's a history with oil leaks on failing oil pressure sensors in Subaru's.
Thanks, I'll have to inspect that. I don't think I've had any oil anywhere above roughly the middle of the block, but I'll be sure to keep an eye on it.
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