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Old 09-20-2016, 03:03 PM   #1
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Default Using oil, smoking on deceleration

Gents,

I've done a cursory internet search, but wanted to ask the question here. I'm traveling on business and won't be able to do a compression check till the weekend.

I cut short my track weekend due to multiple people telling me I'm blowing lots of smoke. It's worst when I'm blipping the throttle during heel-toe action slowing for a turn, but I was told it smokes on acceleration as well. A flagger even called it in and I was stopped at the grid at the end of a session to make sure I knew. I honestly don't see any smoke during normal street driving.

The bottom end has 143k, but the head was rebuilt by Race Engineering about 25k ago. She's still a beast and pulls strong, idles well. She's got 60+ track days since I started doing HPDEs in 2011. The Rotrex was added last May. Oil consumption is increasing--maybe a quart on a hard track day, and I've lost boost. She dyno'd with 9 pounds early this year, but now I see not quite seven. I've checked every hose and tube on the intake side, but I have not removed the intercooler to look for leaks. I don't hear anything that sounds like a leak. There's a yellowish residue on the bumper cover by the exhaust tip that is hard to remove. The vent tubing is standard Kraftwerks. The tube from the driver's side of the cam cover runs to the hose that attaches to the Rotrex, and I have a PCV valve from a Mazda 323 turbo. No catch can. I see low 11s/high 10s AFR at WOT. Using Rotella T6.

Any comments or suggestions for things to check would be greatly appreciated. Thanks,
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Old 09-20-2016, 04:12 PM   #2
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Block off the PVC and see if it clears up. I wonder if you are pressurizing the case.
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Old 09-20-2016, 04:47 PM   #3
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Originally Posted by hi_im_sean View Post
Block off the PVC and see if it clears up. I wonder if you are pressurizing the case.
I thought of that, but could it explain the loss of boost? What about using a small vent filter to replace the hose on the driver's side rather than blocking off the PCV?
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Old 09-20-2016, 05:06 PM   #4
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Valve seals gone?
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Old 09-20-2016, 05:15 PM   #5
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I'd like to think that's not it since the head was rebuilt, but I do abuse her. If the compression checks good, it can't be much else, right?
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Old 09-20-2016, 05:59 PM   #6
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Originally Posted by poormxdad View Post
I thought of that, but could it explain the loss of boost? What about using a small vent filter to replace the hose on the driver's side rather than blocking off the PCV?

If the exhaust side is vented to atmo, or even recirced, I think it would be possible to lose 2psi through a 10mm hose. I just meant block it temporarily to see if it changes states, then you can chase the actual issue. I have never experienced this fwiw, just giving ideas, so take it with a grain of salt.

Stem seals was my 2nd thought. At least those are easy enough to replace on the car.
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Old 09-21-2016, 02:14 PM   #7
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If you need valve seals, i've got a OEM complete set (16)
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Old 09-22-2016, 06:33 PM   #8
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Gents,

Within the context of burning oil and blowing smoke, I had a few minutes to investigate symptoms.

There is no evidence at all of oil in the intake tubing before the throttle body.

The car sat from Sunday evening to Thursday evening (today) and took 15-20 seconds of cranking to start. There seemed to be a little smoke, but I was not prepared for the additional cranking time, and did not have anyone watching for smoke.

Thoughts?
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Old 09-24-2016, 03:37 PM   #9
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Sooooooooooooooooo, I did a cold leak down and a warm compression test.

Leak down. Cyl #1, <5%; Cyl #2 ~3%; Cyl #3 52.6% (average of three tests); Cyl #4 36% (average of three tests). The leakage could be heard through the oil filler cap. Nowhere else.

Compression. 212 / 215 / 215 / 212.

Then I did warm leak down on 3 and 4. 15% and 52%, respectively. The leakage could still be heard through the oil filler cap. Just for giggles I did a warm and wet (so to speak) comp check on #1, in case the gauge was reading high. 219. No smoke on startup.

It's not anything like what I was expecting. Rather than poison the well with speculation, I await the sage knowledge of the group. But please keep in mind, I've lost about two pounds of boost. I'd like to take the car to the track this weekend, but I haven't settled what the issue is.

Thanks,

Last edited by poormxdad; 09-24-2016 at 04:29 PM.
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