question for turbo experts
 

I'm trying to absolutely pinpoint the cause of the smoke. I suspect it's still from the turbo. If you drive around it's fine but smokes on one side only at idle when fully warmed. As soon as you take off again it quits.

I let it idle until it started smoking, and then brought the rpms up to 2000 rpms or so, and the smoking stopped. What I'd like to do is rig a 1/4 turn gate valve in the oil line for that turbo. Get the car up to temp and smoking at idle and shut off the oil for a brief period.

These are water-cooled ballbearing turbos. I cannot imagine shutting off the oil for 20-30 seconds at idle could possibly kill the turbo, but that's the only way to absolutely verify that the oil is coming through that turbo.

Any thoughts from someone who knows more than me? I won't drive the car with the oil shut off, just idle only for 20-30 seconds; that should be enough to make the smoke stop at idle if this is the cause. If it doesn't then it has to be coming from the engine. This is the only way I can think of that will tell me yes or no; I need to cut the oil off immediately while it's smoking to see if stopping the oil stops the smoke. Anything like shutting it off and removing the turbo, etc. takes too much time and effort and it'd have to run a long time to get it back up to temp.

Jody

jody your in take manifold runner is not sealed .
rick k

How would that suck oil on an LS2? :)

Jody

thats right . gen 1 are different than ls 1. 2 . 7 s. do a leak test .
rick k:D

already did. 5-6% all four cylinders cold. Plugs are spotless. I'm just gonna try it, don't think it could possibly hurt it with no load, it'll still have oil in the bearings.

Jody

Jody, have you tried switching the turbos from side to side. If the smoking changes side then you can rule the turbo as a cause. Another thought, could you possibly still have enough oil from the last turbo to still be burning off. Hope you get it sort it out. I would try to swap turbos before you attempt to run the turbo without oil.

Joel

I imagine he would rather avoid the work involved in playing "musical turbos" lol

I can't imagine a few seconds hurting the turbo bearing, especially since they are water cooled bearings. But I'm no turbo bearing expert.

Just went outside and ran the car at idle until it warmed up and started smoking. Took some vise grips and closed off the oil supply line to that turbo. Within 5-10 seconds the smoke drastically reduced, and in about 30 seconds or so it was gone. So I am definitely leaning towards the turbo oil being the cause, now I need to determine why.

The drain line is #10, and identical to the other side. It has a mandrel bent 90 degree fitting off the turbo and a 45 into the front of the oil pan, just under the rail. I have more 45's but there isn't clearance for that off the turbo I don't believe. Since the turbo was re-worked I don't think the issue is there.

Interesting deal, when I took the vise grips off, it takes 2-3 minutes or more for it to start smoking again. Seems like it takes that long to back up in the drain line all the way to the turbo, and then it's forced past the seal. Crimp it again, smoke stops and again another 3 minutes or so without smoke.

I've already checked the line for kinks and removed the fitting from the ATS pan, seems clear , nothing in the way of drainage. The crank turns clockwise so I'd think if that was the issue then the passenger side would be the one with a problem, if the oil off the crank was being shoved back up the drain line.

No final answer yet, but progress. Progress is good. :yes:

Jody

is the line to big or to small? i don't really know much just throwing ideas. when a fuel lines to big for a car it kinda foams up and gets weird could oil be doing the same?

my feed line is #4 with a restricted fitting at the turbo; exactly as Precision recommends. The drain is #10, also their recommendation.

Jody

i relise i may be no help but i serch on google in my bordum and found a few sites that say they strongly suggest no 90s in the return lines and thats a comon way to get oil issues with the turbos. also the holes going into the pan are the same size as the lines. the drain also needs to be above the full oil level. same thing as you said about the windage off the mains may be thrown twords the drain. also they say that excessive high oil pressure at idle/decell will cause the turbos to smoke at idle. i relise some of thats run on and its just what i read. if im not helping tell me. :)

my returns are 3/8" with i think is a -8 and my feeds are 3/16" lines with no problems
a quick diagnostic is to undo your feed line and let it drain it into a can while it is running and smoking, if it stops smoking you know the drain is a restriction, if it still smokes you know your feed is too big or your seal has failed
good luck
jason

turbo issues
 

I assume that this is the same turbo that was smoking before? I thought they were sending you a new turbo... Are they ball bearing or journal bearing?

Can you throw a gauge on your return line? I've seen large frame journal bearing push oil past the seals above 4-5 PSI on the return side. Have you pulled the return from the pan & just let it drain into a bucket? Cap your pan & try that- if it stops smoking, then it's a windage/pan fitting issue. If it smokes, then it's most likely your seal.

Another thought- if you have a pyro on hot side, it should sjow a temp drop as the smoke kicks in; if not, then you might be pulling oil from someplace else (unlikely due to your plug condition).

Lines sizes are correct, but the 90 degree bend on the return is a big no no. Does the other "non smoking" turbo have the same 90 degree bend on the return? Make sure the return line is as steep as possible.

both sides have the same 90; a 45 will run the line into the frame. The other side doesn't smoke.

I tried this initially before Power Tour; it still smokes with the drain line disconnected and run into a bucket, flow through the line looks good. The turbo just had the seal replaced and some machining mod done to it to aid idle oil drain.

I'm going to play with re-routing the drain today if possible, but at first glance it doesn't look like there are many options. I may also have to bend up my own custom hard line with a larger, gentler sweep instead of the shorter 90 mandrel fitting. It's just confusing because the other side is identical and fine that way.
Jody

try a -12 drain. I use a -16 drain on my PT-94

that's a thought, though you'll still have the smaller id of the fittings to deal with. I think the adaptor on the turbo is 1/2" npt but the pan is a 3/8" npt. Then again that's not a restriction as disconnecting it doesn't stop the smoke. It's either backing up in the line itself, or in the turbo body.

I do use push lock hose, so #10 is a true 5/8" id, larger than #10 braided. I'm heading out there soon to start looking at it again. I'm thinking that maybe clocking the middle section of the turbo so it's not quite so vertical may help the 90 flow better, or allow a 45 to be used. I think I run into oil inlet fitting clearance issues though as I remember.

Jody

?????????????

Install A temporary return line without the 90 and dump into a can or bucket. The temp line should eliminate any suspect design issues that are differant from the other side.

Assume nothing!!!!!! Just because human hands have reworked the turbo doesn't mean that it is not the turbo.

Oil getting past the exhaust valve guide would not show on the plugs.

If you had a restrictive return line why would you have a oil issue past the turbo seal at idle which is the lowest preasure/flow. Wouldn't even 2000rpm cause more presure and flow due to no boost to assist the seal yet you said it clears up at 2k???

Worst case and most work but maybe best option is to swap turbos side to side and see if the problem follows. It will possitively eliminate or confirm the turbo and allow you to narrow your focus to either the UPS return label or other areas of the engine I.e. return line design, others sources of oil.

Have you put gauges on both turbo oil supply lines after the restriction orfice and compared the preasures. Do both tubos get oil from the same port? maybe differant presure/flow if not supplied from same port???? Test with gauges and temporary oil feed lines. Supply right turbo with left oil line and so on. Can you control the smoke by restricting the oil presure at idle to a lower amount but more than zero with a small adustable valveand check the effects on the smoke?

Just a bunch of rambling options or thoughts that may break something loose. Good luck. Persistance is your best weapon for kicking Murphy's A$$.

really starting to lean towards clocking the center section of the turbo to more of a 45 degree angle than vertical. Looking at pics of Marks old setup that's how his were which would allow either a straight or 45 bend out of the bottom of the turbo instead of a 90.

Of course the other side works fine that way, but no sense in trying to apply logic here.................. :rofl:

since pinching off the oil line to the turbo stops the smoke I'm eliminating anything from the engine being the cause. As far as idle smoking, at idle the turbo is at it's slowest speeds, sometimes even stalling on twins. As the shaft speeds up it helps direct the oil into the drain port, so the higher the speed the less of a problem it is. That's why smoking due to too much oil shows up at idle, not cruise or wot.

I use one feed split to the two turbo feeds, so pressures should be the same on each side. I could continue to reduce the oil flow to this turbo until it stops, but it's already restricted a bunch with Precisions inlet fitting (.035" hole I believe) so I don't want to drop it much more. I could put something in the line to drop the pressure to 5-9 psi at the turbo at idle ( I currently have 35 psi at idle hot). This was recommended by a very knowledgeable LS turbo guy for the ball bearing turbos; my problem is evidently very common.

Anyone know of an inline adjustable pressure valve I could install in the oil line?

that would drive me nuts! if it were me i would allready have installed a crank case vacuum pump and made sure that the return was above oil leven in the oil pan...

if all else fails.. you can always add an electric scavenging pump like the guys running reat mount turbos do.. that will solve it for sure

thought of that too, but it's just one more thing to fail (with my luck......... :willy: ). The drain is above the oil level, I've run the engine with the line disconnected at the pan, and draining into a bucket, and nothing comes out of the pan.

Jody

How about a fuel preasure regulator. It may not be a good permanant fix but it might work for test purposes.

IMO major changes are not called for yet. You need to pin point exactly what the problem is first! There are to many variables right now. IMO this needs more testing and trouble shooting to narrow the focus. It still may be that turbo and no amount of rework or bandaids is going to fix that. IMO you have to eliminate or confirm the TURBO it self.

When I hit this type of wall an little time off has turned my light bulb on with the solution or a test and normally comes out of thin air for me.

it's either the turbo itself or drain line angle/fitting. I'm eliminating the turbo only because the likelihood of having it bad even after inspection and repair is low. Doesn't mean it's not still an issue, but I'm playing the odds here.

The drain line is fine at and entering the pan, as disconnecting it there doesn't fix it. The fittings and line size are identical for both sides, but I am noticing that the angle of the oil in/out of the turbo is much more vertical on the problem side; the passenger side is clocked further towards 45 degrees to clear the turbo mount pad (not literally 45 degrees, but just to give an idea). This makes the passenger side more downhill out of the turbo drain than the drivers side, noticeably so. The drivers side being almost vertical has the drain fitting putting the oil more horizontal, or at least much more so than the passenger side. This is the direction I'm heading now.

Unfortunately, that requires the turbo to be removed which is a large job; can't reach all the clocking bolts with it installed.

Jody

If when you pinch off the lines the smoke goes away, then the seals in your turbo are bad. 90's 45's and all that is moot, as there should be no oil getting into the exhaust side of the turbo. I've seen people toast them on start up because a lack of oil on start up.

Bad turbo oil seals act like bad vavle stem seals. They'll smoke like crazy at idle and clear out a bit on throttle.

they just replaced the seals on this turbo. The initial one showed "wear" but not exactly sure what that means.

The seal is more like a piston ring than the normal seal like on a guide as you know. They cannot handle puddles of oil against them, which is why if a return pump fails on under-car turbos they immediately smoke like crazy (been there, done that).

So you are correct in that it could be a second bad seal, but that is not all it can be. If the oil is struggling to get out of the turbo and puddling up against the seal, even a perfect seal will do the same thing.

Since it's not an immediate thing, but takes a certain amount of running before it smokes, and again 2-3 minutes after pinching the oil off and then returning oil to the turbo before it smokes, it seems like the oil slowly is building up, backing up, and then finally reaches the seal, overwhelms it, and smokes. I'm in the process of changing the angle of the outlet to match the other side; we'll see if that fixes it.

This is a small amount of oil; the pipe isn't wet at all, just enough , a few drops to make some smoke.

Jody

I believe someone asked previously, but what oil pressure are you getting to the turbo? Is the pressure to high?

What is your source for the oil feed?

I have never seen a return create such a buildup though. Do you think that because of a restriction in the return side that the feed side is creating a pressure to high in the center section. Is that what your thinking?

Hope I am not being a pain, just a curious bystander here.

I have 35 psi hot at idle. Both turbos feed off the same line, which is tee'd in the center to feed them. My latest thought, for what it's worth, is that the 90 degree fitting on the outlet (required due to frame clearance issues) is too upright of an angle. In other words the fitting comes almost straight down off the turbo and then is almost horizontal at the end of the bend. The other side has the center section clocked differently so that it's app. a 45 degree angle off the turbo to the outside of the car, then turns 90 degrees to be 45 degrees down again towards the oil pan. This is the only difference in the two sides, identical fittings, line sizes, etc. My thought is that this could be the difference in flow backing up, because when I ran the car with the drain line running into the bucket I was surprised how much flow comes out of that line, considering it's reduced to only a .035" hole on the inlet fitting.

The next step will be to find an inline regulator of some sort to reduce the oil pressure at the turbo. I'm told the ball bearing turbos only need 5-9 psi at the turbo, and I'm way past that.
Jody

maybe the seals are already toast... but they shouldnt be..

Jody if it were me id start playing with the drain size of the pan I still think that has somehting todo with the smoke but thats me.

Missed that earlier.

Can you clerify the bold statements? You say you had no flow and then you have flow? What was the difference between the two scenarios, the 90?

Also I have always pulled from a low pressure source to feed a turbo, becasue of the isssue of blowin seal.

One more question if I may, do the returns from each turbo merge, or do they have their own return fitting on the oil pan?

With the speeds that a tubine spins, even at idle, that friction with no oil can burn up the seals real quick.

I was looking at the motor on your website, man that is sick. It looked like both oil returns were clocked to about the 4 or 5 position, is that correct?

yeah, but disconnecting the line at the pan did not stop the smoke. Or do you mena a larger drain line? Thing is 5/8" i.d. is plenty big according to pretty much everyone. That's what was on here with the old motor too I believe.

Jody

No flow was the return line disconnected at the pan, no flow from the pan fitting. That means the fitting is not below the oil level in the pan, and there isn't any pressure inside at idle from whipping oil, as nothing came out of the fitting, I did not cap it.

The flow that surprised was the actual drain line off the turbo emptying into a bucket; quite a bit more oil than I expected to see.

Oil lines are separate, one into the front side of the pan, one at each side. The passenger side drain line is clocked at about 7:30-8 o'clock, the drivers side is between 5 and 6, more vertical.

I do not know of a low pressure area to pull the oil from; this is a fitting on the oil pan provided by ATS for an oil feed or pressure gauge.



Jody

I use a single -16 (3/4") when i test fired my motor and had no oil problems but your running a small frame turbo and im running a large frame. so there is some differences

If it were me id up grade to a larger line.

Oh BTW jody i went and picked up the paint!

cool.......... :thumbsup: Orange???

Jody

Jody don't worry about the pressure going into the turbo. Lots of cars out there with way more than 35psi of oil pressure into the turbo. What sucks is that you need a 90 to drain of the turbo. I bet it you can get that as straight as possible the smoke will go away. Glad to hear the motor isn't the problem! :thumbsup:

So when do we get to see video of the beast on the road???

If it was a drainage problem then I would think it would smoke while driving not at idle. Also both sides would smoke because they have the same drain size. I bet if you rotate that turbo to match the non problematic side it fixes your problem. No turbo expert but that side works and everything else is the same.

yep :)

Did you catch my fuel preasure regulator suggestion as a tempory test for adjusting oil feed preasure/flow?

If repositioning the drain fitting to make the angle the same is resonably easy I would go there first. But the assumtion that is still bothering me is the Turbo having a fresh seal. It took FOUR prochargers on one of the projects I was building at Hot Rod Garage before we got a low boost/noise problem fixed. They repaired 3 of them and we finally told them we wanted a new unit because that is what the customer purchased and no more repaired units. That fixed it. If it failed ounce and there wasn't a completely obvious problem they still may not have found the original issue i.e. something machined wrong or some run out issue. I have fought this more than once.

Can you put a temporary drain hose with a rubber line and staight fitting in place of the 90 fitting as a test?

If you can't come up with a regulator can you put a smaller orfice in place to reduce the flow to the turbo?

It may be a combination issue, marginally high flow, marginal drain fitting/angle, and marginal turbo seal.

IMO just food for thought.

good thoughts. I already re-clocked the turbo. Just have to add coolant and attach the lower drain fitting and it's done. I'll let you know how it goes................. :)