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Blow by from valve cover


Guest Anonymous

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Guest Anonymous

I had smoke coming from valve cover similar to previous thread. Pulled all my pistons today and

found no broken ring lands??? Any other ideas? motor is fresh rebuild only about 100 mi on it untill it starts to smoke. Valve seals and guide are new too.

Thanks

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No way around it, some how air presure is excaping the combustion chambers either through the crank case or through the head. I'm not sure that this means that you have a problem that is hurting performance, but after things are back together it'd be worth doing a compression check/leak down test.

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Guest Tim78zt

I've been researching this trouble, mostly to figure out which rings to buy if my leakdown test results say that is what I need, since I opened the discussion with the previous thread. My engine acts like nothing is wrong... strong power and no extraneous sounds, but intermittant blowby, meaning it doesn't always do it and sometimes are worse than others. I'm wondering if the ring gaps have lined up somehow and that is allowing the vapor to escape from the crankcase?

We can assume that you followed proper break-in procedure to allow the rings to seat, so I am out of ideas. Anyone think of something?

 

Tim78zt

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Some amount of blowby is normal for a turbo engine. The more boost you run, the more blowby you will get. This is why I have oil traps in my PCV lines...

engine1.jpg

 

The y-shaped piece takes the oil out of the blow by gas and drains it back to the oil pan.

 

If your ring lands look okay, and your compression/leakdown test results look okay, then you probably just fall into the 'normal' category.

 

How much is not normal? If you have a broken ring land, you will probably see enough blowby for oil to start leaking out around the oil filler cap on the valve cover. If it's not doing that, then I wouldn't fret too much.

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Guest Anonymous

Sorry to get off topic.. but Bushido, you have a gorgeous Z! What bumpers are those?

And TimZ.. where do you buy all your braided hose/fittings? The cheapest I've found them are aeroquip from baker precision.. moderately cheap to scale, but still a heck of a lot of money! bonk.gif

-980mak rockon.gif

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  • 2 weeks later...
Guest Anonymous

thanks for the responces, I am thinking that I have normal blow by, I am just not used to turbo motors. I replaced the rings since I had the motor apart and ran it. It still has blow by but must not be severe. Now I have a new problem, I used total seal rings, thought they might help with the blowby. Now I have a horrible vibration in the engine, only at about 2200 rpm and then it goes away or I cant feel it because of the increase in freq, but its bad it shakes the car. Would rings cause this?

Thanks again

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