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?