2G Oil burning exhaust NOT the turbo

[gdb1039]

I just had a similar situation. Car smoking badly, rebuilt turbo to no avail. I pulled the exhaust manifold and found oil leaking into the exhaust manifold from a exhaust stud. The lower stud by runner 4 goes into a oil gallery. The threads in the head was worn out so I put in a helicoil and used high temp rtv. Problem solved

 

[kjlinwi]

Pulled exhaust manifold. I have oil sitting on the exhaust ports of cylinders one and four, cylinder 3 shows signs of oil and #2 is def dry. There is oil in the manifold as well. Time to contact the machine shop.

Matt

 

[gsxeclipse102]

That sucks. Maybe they put the wrong valve seals in.

 

[livedsm4g63]

Glad to hear you were able to figure this out.

 

[kjlinwi]

Worse part is that we supplied the valve seals to the machine shop since they were included in the head gasket kit.

 

[Tyeler18]

They get cut on install pretty often. I've had enough issues in the past with out side sources installing them, that I make sure to install them all myself now. Too much hassle for something so small.

 

[kjlinwi]

"As far as turning off the turbo in link, he's right. It doesn't work like that. You are limited to the minimum amount of pressure your wastegate spring is rated at. An MHI wastegate spring is 7-8PSI for a 14b/16g setup. You can turn the duty cycle to zero in link, you can loop the wastegate line to the wastegate itself bypassing the controller completely, it will still boost 7-8psi. You can't "shut it off" completely, even with the wastegate tied fully open it'll still have flow past the turbine wheel allowing boost to build to an extent. If you're turning anything off in link and driving around with 0PSI of boost you have a mechanical failure, boost leak, bad turbo etc. Just want to clear that up for someone who may find this thread later on."

I wasn't going to respond but WTH. Poke the bear.....

"A turbo cannot be turned off, in link, or any other way. Even if you could turn off the boost (only way to do this is have all the exhaust bypass the turbine), oil would still flow into the turbo"

I grant that stating I'm turning off the turbo could be misleading. I've set it so that I'm boosting very little so that the turbo RPM is reduced to see if it made a difference in the smoke output. More RPM more smoke, less RPM less smoke is information worth knowing. But I also said that I have it set so that there is no boost. I thought that would have helped clear it up, obviously I was mistaken.

In your and the other examples of it "always boosting" there would then be no intake vacuum since the turbo is always spinning and "even with the wastegate tied fully open it'll still have flow past the turbine wheel allowing boost to build to an extent..." Completely false misinformation.

IF this were true, then your power brake booster would never work because you would always be building boost and never have engine vacuum. And brake boosters need engine vacuum to work. How do you get engine vacuum with a turbo that's always boosting? Lets not even get into turbo lag and spool times.

You CAN adjust it so that there is very little to no boost while driving so that you can make your adjustments before adding in the boost.

START your own POST. POST your VIDEOS showing 20 PSI BOOST in NEUTRAL with car sitting still. Don't tell me to do your dirty work for you and go "google" it. You make an assertion, you do the grunt work and prove it. Go armchair quarterback someone else who might believe you. Done this way too long to sit here and take this crap.

Matt

 

[91talonts1]

You still are wrong... This is why people don't trust mechanics. No one said it's always making boost, it's always CAPABLE of building boost.

Stop posting about it, as the other guy said, other people will see this thread and think you're right. Because they don't know any better.

 

[kjlinwi]

WOW, waffle much?

This was posted earlier by someone else:
" even with the wastegate tied fully open it'll still have flow past the turbine wheel allowing boost to build "

Sounds exactly like what I said is wrong and exactly what you just said no one said.

Now it's not building boost, but it's capable of building boost? What does that look like on a gauge? Zero boost or intake manifold vacuum. You have made no attempt to explain how a turbo car has engine vacuum to operate the brakes while driving at 2000 rpm.

I'm educated, tested and certified that I know what I'm talking about. Where's yours?

Don't blame me because you don't understand all the intricacies of how it works.

Talk is cheap, post your video that you bragged you could make.

 

[gsxeclipse102]

I will chime in on this one. Revving a turbocharged car in neutral will not build up boost. There is 0 load on the engine. Turbos work off pressure and heat. Not rpms. This is the reason you can drive at 4k rpms and have no boost. Theres no heavy load. Also you can not turn off a turbocharger. When turning an electronic boost controller all the way down you are left with wastegate spring pressure. Also a brake booster has an inline check valve so it never sees any positive pressure.

 

[livedsm4g63]

Let the pissing match...Begin..
OP has found his problem. No need to keep posting useless information.

Everyone knows that if you have an ebc and you turn it to zero the turbo will still spool to whatever the waste gate spring rate is. Now if you have a variable spring rate for a waste gate, then there should be a discussion on how you did this as this would be a conversational piece.

To anyone's certification, this doesn't mean a thing. A blind squirrel can always find a nut.

 

[91talonts1]

WOW, waffle much?

This was posted earlier by someone else:
" even with the wastegate tied fully open it'll still have flow past the turbine wheel allowing boost to build "

Sounds exactly like what I said is wrong and exactly what you just said no one said.

Now it's not building boost, but it's capable of building boost? What does that look like on a gauge? Zero boost or intake manifold vacuum. You have made no attempt to explain how a turbo car has engine vacuum to operate the brakes while driving at 2000 rpm.

I'm educated, tested and certified that I know what I'm talking about. Where's yours?

Don't blame me because you don't understand all the intricacies of how it works.

Talk is cheap, post your video that you bragged you could make.

This is not a pissing match for whoever just said that. This guy doesn't understand how a turbo engine works plain and simple just from this post alone.

 

[kjlinwi]

Service Manual Description for a 2010 Chevy Cobalt SS Turbo Car

Turbocharger Description and Operation
A turbocharger is a compressor that is used to increase the power output of an engine by increasing the mass of the oxygen and therefore the fuel entering the engine. This BorgWarner™ dual-scroll turbocharger is mounted on the exhaust manifold and the lightweight turbine is driven by the waste energy generated by the flow of the exhaust gases. The turbine is connected by a shaft to the compressor which is mounted in the induction system of the engine. The compressor vanes compress the intake air above atmospheric pressure, thereby greatly increasing the density of the air entering the engine. The turbocharger is capable of producing up to 18 psi or 1.24 bar, of power-enhancing boost.

The turbocharger incorporates a wastegate that is controlled by a pressure differential, that is determined by the engine control module (ECM) by means of a PWM solenoid, in order to regulate the pressure ratio of the compressor. A charge air bypass valve also controlled by the ECM by utilizing a remotely mounted solenoid is integrated into the unit to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions. When the bypass valve is open during closed throttle deceleration conditions, the bypass valve allows the air to recirculate in the turbocharger and maintain compressor speed. Within a calibrated range during the closed throttle event, or upon a wide open throttle command the bypass valve will then close to optimize turbo response.

The turbocharger is connected to the engine oiling system by a supply and drain tube and Mobil 1™ synthetic oil is installed at the factory. Synthetic oil is required for its friction-reducing capabilities and high-temperature performance. There is a cooling system circuit in the turbocharger that utilizes the engine coolant to further reduce operating temperatures.
__________________________________________________________________________________________
The take away from this is that turbos are not all on all the time. The PCM (via the software) can move the wastegate to control boost in different operating conditions based on program parameters and inputs. This is also why there are variable vane turbos, variable displacement turbos and some systems using sequential turbos.

You can't run boost all the time, the engine needs to make vacuum most of the time.

For those who want to actually learn. For the know it alls.... Continue on!

 

[91talonts1]

Nothing you just posted applies to a dsm. This ain't a Cobalt forum!

 

[livedsm4g63]

This is not a pissing match for whoever just said that. This guy doesn't understand how a turbo engine works plain and simple just from this post alone.

Though I do agree with you, anyone in their right mind knows how a turbo works. If someone comes in and reads all of the posting, Im fairly certain they will gain the concept.

To add to the pissing, where did you state you were running a variable vane turbo, variable waste gate pressures, etc? Last I checked you arn't running a POS GM product.

 

[91talonts1]

I will chime in on this one. Revving a turbocharged car in neutral will not build up boost. There is 0 load on the engine. Turbos work off pressure and heat. Not rpms. This is the reason you can drive at 4k rpms and have no boost. Theres no heavy load. Also you can not turn off a turbocharger. When turning an electronic boost controller all the way down you are left with wastegate spring pressure. Also a brake booster has an inline check valve so it never sees any positive pressure.

Revving in neutral will not build boost as every time the throttle snaps shut, it's under vacuum again. Holding the throttle open in neutral and limiting the revs, will produce boost with zero load. It's what you're doing everytime you use the two step.

 

[kjlinwi]

Finally an intelligent life on here!!! Gsxeclipse102 Glad you exist . To answer your comment, about the brake booster your correct, most cars do have a check valve in there, but its more so that the booster doesn't lose it's vacuum under boost conditions for a turbvo car and even a na car under close to full throttle condition. THe brake booster will actually hold vacuum KOEO almost indefinitely. You can deplete the booster by pumping the brake until its rock solid koeo.

To the discussion, if a car always boosted though, you couldn't run a vacuum booster, you would have to run hydroboost.

And your absolutely correct that you need cylinder pressure to get a turbo to spool and build boost. Hence why I asked for the car building 20 psi boost in neutral that is still not posted

The rest of the crowd knows it all evidently and I learned along time ago that you can't teach stupid.

I'm out of here before I really let loose and get my wife membership in trouble.

I knew it was a bad idea to post here in the first place. Armchair quarterbacks everywhere spouting off false information as gospel. And when you point it out, it's a pissing match of who said what.....Yeah ok. Logic doesn't work here.

That's why I should have stayed out and I will from now on. Lifes too short to deal with wannabees.

I'm gone. Have fun.

 

[91talonts1]

Hence why I asked for the car building 20 psi boost in neutral that is still not posted

You must be logged in to view this image or video.

How bout 30 instead?

 

[gsxeclipse102]

91talonts1 bro your talking about something completely different. Were talking about revving your car in neutral. No launch control

 

[91talonts1]

Re read through his posts, and you'll see that's not what he's talking about. Again as I said free revving it the throttle goes shut, thus producing vacuum. The wastegate, boost controller, vss, ecmlink anything else he mentioned has nothing to do with it.

Same goes for your power brakes work after boosting. The throttle is shut the manifold only sees vacuum.

He is not turning boost off completely, or at all unless he's stuck his wastegate open. If you'll note the boost gauge when you free rev your car it will shoot toward zero, that's the turbo building positive pressure. No launch control, pressure does not climb high because the exhaust flow isn't there and the throttle doesn't stay open, but intake pressure is most definitely still there.

 

[gsxeclipse102]

If you hold your throttle open at a constant 5k rpms you wont build boost. The boost gauge goes to 0 because your out of vacuum and 0 is atmospheric pressure. It wont go any higher. He even stated later on that hes not actually tuning off the boost just limiting it to the lowest it will go. Again you cant build boost in neutral without using a launch control. Go post a video of you holding the throttle open at 5k rpms and where your boost gauge is.

 

[ThunderChild]

Ok, here's the big deal. Turbo are not positive displacement pumps. They will not produce boost at all times. They're exponential, and require load and rpm to compress air. As many have stated, boost will be relegated to wastegate spring pressure if the boost controller is turned all the way down. A turbo will generally not produce boost in an unloaded situation (nuetral), unless tuning parameters are altered (2 step, launch control or anti-lag), but there are more factors to consider behind that.

At idle and unloaded areas the engine will be in a vacuum state, as the turbo has not crossed the boost threshold to provide positive pressure yet, and it is difficult to do so with no load on the engine.

Still, you cannot "turn off" a turbocharger, you can only keep the wastegate pressure low enough that you may not see active pressure in the system, which will still only be effective at idle or unloaded situations. As soon as you start applying load (driving) then the potential to cross the boost threshold is increased and easier to accomplish.

The boost gauge will go to zero when revving in neutral because you've equalized the pressure in the intake tract to atmospheric pressure, not because the turbo is doing that work for you.

Either way. You're both kind of right, but you both kind of need to stop bickering and get back to the topic.

 

[gsxeclipse102]

I already helped the op. He found his oil leak from the cylinder head. Im not trying to fight with anyone. Just educate and in this case clear up some information/misunderstanding but i am done here. All questions have been answered

 

[91talonts1]

Same here, you can't read people's tones.

Though I still don't think we're all on the same page, we'll leave it at that, as you're right this has gotten out of hand.

 

[bling5tatus]

Sparkcut antilag builds boost without the car being in gear and no "load" on the engine.