cpt_koolbeenz

So, no matter how hard I tried, I am a rolling fog machine... super.

I know it is the turbo... Spark plugs are not oily, intake tract is clean... So it is not valve guide seals. My engine only has 6000 miles on it too, with a full rebuild.

It is also symptomatic of a turbo with leaky seals... Smokes on idle usually after it has been idling for a while. It smokes on hard acceleration somewhat. Or sometimes it won't smoke at all.

I have been doing some research and testing. I read a bunch of posts about smoking turbos, and found nothing that really lead to the problem.

Yes, I do vent my crankcase to the atmosphere with a 5/8 hose. Before you get your knickers in a twist, read the following:

There are several people out there that are adamant about venting the crankcase back into the intake to put the system under vacuum in hopes of allowing the turbo to drain better. HOWEVER, there is very little vacuum under idle where the stock crankcase vacuum port plugs into the J boot. Vacuum could help under boost conditions where there is a lot of blow by, but at idle, vacuum is very, very minimal under the stock setup. Not to be confused with intake manifold vacuum (which is pretty high at idle). If that was not enough, the stock AOS has the restrictor in it. So, at idle, crankcase vacuum is nonexistent.

So, for fun, when my car was smoking and idling, I hooked a shopvac up to the oil filler neck and blocked off my vent. I was pulling about 3-4 inHg for about 10 minutes, and there was no change, not even a little.

At first, I had a 1/8" or ~120 thou restrictor on the turbo for about 5.5k miles. Then, in hopes of fixing the smoking, I went with a 1/16" or ~65 thou restrictor. That didn't help either (as far as I can tell).

So, to add to the long list of smoking turbo owners (or ex owners) like david fracolli, rage, zero10, jimbo1111, Rob, emwporsche, Por951turbo, etc, add my name.

Rage, your turbo was a TEC right? What were your symptoms? Did you get it fixed?

Rob, did you have a TEC turbo? I saw you got it rebuilt and all was well... is it still that way? Where did you get it rebuilt?

Por951turbo, you solved your smoking problem by actually venting to the ATM, correct? That would sort of shoot holes in the vacuum scavange theory!

TEC, or rather Jim, at TEC, has first ruined my engine, causing a complete rebuild and $4500 later, and now his turbo needs to be rebuilt at 6000 miles! Even better, he won't help me out, telling me I'm full of ****! Nice guy!

Anyway, just was looking to stir up a little more background on smoking turbos, oil pressure, crankcase vents, particularly TEC turbos...

mark944turbo

When you did the rebuild, did you glue the valve stem seals to the head if you replaced them? I just recently started doing this after finding that the valve seals now available are larger than the original ones, and will fall off quickly if not glued.

"I know it is the turbo... Spark plugs are not oily, intake tract is clean... So it is not valve guide seals. My engine only has 6000 miles on it too, with a full rebuild. "

Any time you are burning oil the spark plugs will show it, no matter where it came from. A clean intake tract would indicate that it is not the turbo if anything. I would take a few valve springs out and see if the seals have popped off, I almost guarantee this is the problem if you replaced them recently.

AlexE

Before giving up.......... regardless of the testing you have done.

I would run ........

1. 50 thou restrictor
2. Run a hose from crankcase vent back to jboot
3. 20-50 oil

I would run it like this for at least 500 miles.

david fracolli

I have to disagree about it beingthe valve stem seals. Everyone told me that it was a blow by problem and not the turbo. I tried many different things with no luck. I was going to install a restrictor but the seals went before I was able to put it in. The thing that really made me sure it was the seals was when I went through a quart of oil on the 16 mile drive home from work!

Magown

Mark the seals can fail on the center section of the turbo and dump oil directly into the turbine and down the down pipe, it will never come in contact with the plugs and it will easily fog an entire city blown with smoke.

david fracolli

That is exactly what happened with my turbo.

eclou

My car smoked like that once when I experimented with putting an inline ball-check valve on the line from the AOS to the hardpipe. I wanted to limit the oil in the intake tract. All I got was a motor that would smoke like mad at idle. Removing the valve instantly solved my problems (I had already drilled the AOS).

The AOS vacuum phenomenon exists. It is mystical, revered, misunderstood, and feared. Do not mock its essence.

cpt_koolbeenz

<<<1. 50 thou restrictor
2. Run a hose from crankcase vent back to jboot
3. 20-50 oil>>>

I could run a smaller restrictor... but that is getting pretty small. I could not even find a bit that small.

I cannot vent the crankcase in front of the turbo... My intake setup doesn't have a nipple for that. I could vent my crankcase to the intake directly... but that is kinda sketchy with a drilled AOS!

I will try the heavy oil next oil change...



<<<My car smoked like that once when I experimented with putting an inline ball-check valve on the line from the AOS to the hardpipe. I wanted to limit the oil in the intake tract. All I got was a motor that would smoke like mad at idle. Removing the valve instantly solved my problems (I had already drilled the AOS).

The AOS vacuum phenomenon exists. It is mystical, revered, misunderstood, and feared. Do not mock its essence.>>>

You had a line from the AOS to the hardpipe? You were pressurizing the crankcase under boost? Doesn't sound good.

I would believe you when you said it smoked... You were blocking off your only vent for the crankcase. I am venting mine through a large opening. My turbo even smoked when I took off the oil fill cap.

I also measured the crankcase pressure with a very sensitive gauge. There was NO pressure in the crankcase with my setup at idle. Anyone else have this happen to a new(er) turbo or a TEC?

eclou

Clarification - AOS was routed to the hardpipe MAF elbow, not the boost tubes.

Sam Lin

WTF are you talking about?

Sam

Rogue_Ant

Chris, sorry to hear about your issues. I've had problems in a past vehicle with the return line causing the turbo to smoke (badly), BTW that was just the turbine side of the turbo too...

cpt_koolbeenz

Hey thanks man.... I think I will pull off the return line for fun tomorrow and see what I can see...

How is your ride holding up? We should get together when you have an afternoon.

Rogue_Ant

Car is great! Still pretty much stock, just been enjoying it. And yeah, should definitely meet up.

special tool

I have been the most adamant about this - but you need to reread my posts.
The crankcase vac necessity has NOTHING to do with the crankcase- it is the secondary effect it has in pulling the oil away fom the turbo oil seals.
BECAUSE THE VACUUM PULLS (ASSISTS) THE OIL DOWN THE LARGE BRAIDED STEEL TURBO OIL DRAIN LINE.
Now go hook up your vacuum system the way Porsche designed it, and the smoke will go away and quit being a turkey.
The shop vac is not enough - and you didn't get a good seal, anyway.

Rogue_Ant

Sounds to me like he already had a vacuum source hooked up....


Rogue