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Old 07-01-2007, 11:48 PM   #1
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Default Smoking from tailpipe during boost

Well I just got done installing my turbo setup and took it for a drive.. while getting in boost, i get quite a bit of whiteish smoke pouring out the tailpipe..

I'm assuming its actually blue-ish smoke and is oil burning.. anyways..

It's a brand new 16g turbo with megan mani/dp.. I was under the impression that the turbo had a built in oil restrictor but maybe it doesnt?

I put in a 323 GTX PCV valve but no difference.

The pan is tapped but maybe the drain isnt quite perfect? Ill try to post a picture in a second..

The only other thing i can think of is it has blowby, could it have that much extreme of blowby?
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Old 07-01-2007, 11:51 PM   #2
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Is it an MHI 16G or a China special?
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Old 07-02-2007, 12:08 AM   #3
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Got it off of ebay so im guessing china

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Is it an MHI 16G or a China special?
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Old 07-02-2007, 12:09 AM   #4
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One more thing i forgot to mention, the driver's side valve cover breather isnt yet hooked up to the intake path it just had a breather filter hooked up.. that couldnt cause it to smoke that bad tho could it?

Also, every once in a while when i get home and turn it off, there is a little bit of smoke coming off of the exhaust side of the turbo housing
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Old 07-02-2007, 01:14 AM   #5
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could a bad pcv (clogged pcv port) allow oil to blow out of the breather onto the hot turbo/manifold? just spitballin' here
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Old 07-02-2007, 07:59 AM   #6
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I just replaced the PCV and it made no difference

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could a bad pcv (clogged pcv port) allow oil to blow out of the breather onto the hot turbo/manifold? just spitballin' here
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Old 07-02-2007, 10:33 AM   #7
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If you don't even have your driver's-side breather hooked up to a constant vacuum, then, yes, it could easily be causing smoking.
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Old 07-02-2007, 09:09 PM   #8
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This is quite a bit of smoke.. I wasn't aware it would make that huge of a difference, the car is about 240 miles away i live on an air force base in louisianna and my car is in texas at my parents house.. so next time im in town ill try to rig that up and see what happens..

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If you don't even have your driver's-side breather hooked up to a constant vacuum, then, yes, it could easily be causing smoking.
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Old 07-03-2007, 12:19 AM   #9
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Well, if it's truly as much smoke as you say, then, yes, routing the breather correctly likely won't eradicate the problem entirely, but you should try it just for the heck of it.
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Old 07-03-2007, 04:13 AM   #10
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Quote:
Originally Posted by Brian View Post
If you don't even have your driver's-side breather hooked up to a constant vacuum, then, yes, it could easily be causing smoking.
What's the best way to do this? Route it back into the intake? Wouldn't that just pressurize the crankcase?
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Old 07-03-2007, 04:20 AM   #11
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See this thread. https://www.miataturbo.net/forums/sh...ad.php?t=10930

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If you don't even have your driver's-side breather hooked up to a constant vacuum, then, yes, it could easily be causing smoking.
What? bad advice.

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What's the best way to do this? Route it back into the intake? Wouldn't that just pressurize the crankcase?
Yes it would. The breather (driver side) should go before the turbo after the maf (if equiped)

Last edited by Braineack; 07-03-2007 at 09:22 AM.
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Old 07-03-2007, 09:15 AM   #12
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Yes, route it to the intake; not a charge/intercooler pipe, but the one at the turbo inlet that'll see constant vacuum.
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Old 07-03-2007, 09:25 AM   #13
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I'd double check the drain line is ok. triple check the PCV valve works (find air compressor). reroute the breather line. possible add restrictor in turbo (-4AN line?)
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Old 07-03-2007, 02:26 PM   #14
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Quote:
Originally Posted by Brian View Post
Yes, route it to the intake; not a charge/intercooler pipe, but the one at the turbo inlet that'll see constant vacuum.
There isn't much vacuum at the turbo inlet. The airflow at that point in the system is a large volume of air with little vacuum or pressure. After the turbo before the throttle is mostly pressure and after the throttle is vacuum and pressure. If you have vacuum at the turbo's inlet then you have a blocked air filter.
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Old 07-03-2007, 03:12 PM   #15
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you're still going to have 1-2 ~hg. Anything more than that and you have a restriction. Yes it's little, but yes that little bit of a vacuum helps pull the oil out of the turbo and helps seals the rings a bit better when in boost.

think about this: you're idling and you blow into your breather line, you'll see blue smoke out of the exhaust. You can blow enough pressure (about 15kPa at the extreme or 2psi) to force the oil back up into the turbo and start blowing past the oil seals into the exhaust.

At 2~hg. (as tested by Corky Bell at 9psi on his S1 kit) you're pulling about 1psi out of the crankcase, which will be just enough to help pull the oil out of the turbo, and in the least equalize the pressure different from compression loss or a leaking pcv.

in other words, it doesn't hurt.

in my case, I couldn't even put an catch-can on my breather line. The pressure drop from it was enough cancel the vacuum. Which lead to me burning smoke on decel out of boost. (I had bad rings). As soon as I removed the catch-can form the line and put it back driectly to the intake, the smoke was eliminated.

Last edited by Braineack; 07-03-2007 at 03:29 PM.
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Old 07-03-2007, 04:17 PM   #16
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It's funny, huh, Scott...after lo these many years of preaching the benefits of correctly routing the PCV system, some people still don't buy it.
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Old 07-09-2007, 10:55 PM   #17
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Update: I re-clocked the turbo so the oil return pointed more straightdown, routed the drivers side breather to the intake pipe right before the turbo, and put another turbo 323 PCV valve in..

One of those things fixed the problem, under boost i see no smoke pouring out of the tail pipe..

Next problem, after driving around town for a weekend quite a bit.. the oil and coolant was fine..

However, on the 240 mile trip home from texas to louisianna, it burned or leaked 5 QUARTS of oil.. wtf?

Rings? i have no idea, ill do a compression check this weekend but wtf is the problem?
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Old 07-09-2007, 11:58 PM   #18
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Well i just took it for a drive.. its starting to smoke again in boost, but now it stumbles really bad when entering boost, which could be a totally different issue, or could it?
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Old 07-10-2007, 12:57 AM   #19
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Quote:
Originally Posted by greenday3437 View Post
However, on the 240 mile trip home from texas to louisianna, it burned or
The thing only holds 3.6qts by the book... so I'd say you've got a problem.
I'm surprised nobody has asked you for your compression numbers yet. Do a compression check and report back.
Is there any oil in the charge piping?
Are you running a cat?
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Old 07-10-2007, 04:07 AM   #20
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Quote:
Originally Posted by Braineack View Post
you're still going to have 1-2 ~hg. Anything more than that and you have a restriction. Yes it's little, but yes that little bit of a vacuum helps pull the oil out of the turbo and helps seals the rings a bit better when in boost.

think about this: you're idling and you blow into your breather line, you'll see blue smoke out of the exhaust. You can blow enough pressure (about 15kPa at the extreme or 2psi) to force the oil back up into the turbo and start blowing past the oil seals into the exhaust.

At 2~hg. (as tested by Corky Bell at 9psi on his S1 kit) you're pulling about 1psi out of the crankcase, which will be just enough to help pull the oil out of the turbo, and in the least equalize the pressure different from compression loss or a leaking pcv.

in other words, it doesn't hurt.

in my case, I couldn't even put an catch-can on my breather line. The pressure drop from it was enough cancel the vacuum. Which lead to me burning smoke on decel out of boost. (I had bad rings). As soon as I removed the catch-can form the line and put it back driectly to the intake, the smoke was eliminated.
What do you mean pull the oil out of the turbo?
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