MEAN GTO

iTrader: (1)

Hi fellas. So back in 2009 I had a twin turbo setup fabricated using two new, Precision 6265 journal bearing, billet turbos. Everything was great until the motor popped. Ring lands on 4 pistons got busted.

A couple years later I had the car running again, with the same engine-- I just cleaned things up and put in some new, stock pistons until I could figure out what caused the engine to pop. There was a little bit of blue-ish smoke I was noticing at idle after the rebuild, which I attributed to a small score on one of the cylinder walls after the engine failure.

I got a few hundred miles on the rebuilt engine and it popped again. Found that I had a shitty tune (thank you Behe Performance ) and decided to drop in a 5.3L engine this time around. This was a salvage motor that was obviously just rebuilt and was in great shape, but instead of carrying over my low-mileage LS2 oil pump I decided to install a Melling high volume pump. I later found this wasn't the best idea on a turbo motor, but after firing up this 5.3 there were no immediate signs of ill effects. I primed the turbos and engine before firing it up (like I always do) and there was no smoke coming from the exhaust. I then drove the car for 30 minutes and still no smoke. The next day, while idling, my buddy who was following me noticed some blue smoke coming from the exhaust. I assumed and hoped it was maybe some residual oil in the exhaust from the last engine, and today was the day to take the car to Pennsylvania to get it retuned, so we continued driving it with my buddy behind me.

After a few hours of driving the smoking completely cleared up. No smoke at idle, not under load while driving, so we were certain it was just residual oil. A few weeks later the shop doing the new tune fires the car up and it starts smoking pretty badly at oil. It then got worse as they gave it throttle. They were confident the smoke was coming from the exhaust side of the turbos. I did some reading and found that the high oil pressure could be attributing to this issue, so I ordered some Vibrant oil restrictors and the shop installed them. The restrictors were first installed without any jets and this didn't help. Then the largest of the two jets were installed and still smoking. The smallest jets were installed and now things were looking good at idle, but at 4,500+ RPM it was still smoking.

I just hauled the car back down from PA yesterday and will be getting around to doing some troubleshooting of my own, but was curious if anyone may have any idea why the turbos weren't smoking until after I started driving the car more after the first half-hour or so of driving it. I did have a factory rocker trunion break on the last set of heads that were on the last engine when it blew. I found a few needle bearings caught in the screen of the oil pickup tube, but most of the needles were still in the cylinder head when I tore the previous engine down. Not sure if any needle bearings (or other debris) possibly made it past the pickup screen and into the lines going to the turbos and maybe have done some damage to the turbos..... or maybe I still have too much oil pressure coming into the turbos.

I have a -4 feed coming off the side of the oil pan, going into a -4 Y, and two more -4 lines (one to each turbo). My drains are -8 and weren't previously a problem with at least the original 6.0 engine.

I do have a friend who has taken apart turbos, and I feel mechanically inclined enough to tear my own turbos apart with his help, I just don't know where I can get parts (ie: journal bearings, exhaust seals, etc.) if I do end up needing to replace any of the internals. The turbos don't even have but around 1,000 miles on them over the past years (car has sat in a garage for several years since the turbo build), so they shouldn't need much I hope. I just don't feel confident about sending them to Precision to be charged something to the tune of of $900/ea for repairs due to "oil contamination"... whether that was a problem or not. Seems like Precision uses this line with all of the customers with smoking turbos, and I don't want to excessively over-pay for a repair that I can do for probably less than $100 in parts... provided I can get my hands on the replacement parts.

Any assistance would be really appreciated on this. Thanks!!

EDIT: I failed to mention that for my PCV system I have a breather on each valve cover, and a non-breather oil filler cap.

mkvamso

iTrader: (2)

Have you checked to see if theres oil in the charge pipe or intercooler
If so the seals are probably going out on the turbos, or you're giving them too much oil to handle
If there's no oil in the cold side, it's probably a turbo drain issue causing the oil to burn in the downpipes

lsx1

It needs a -10 minimum on the drains.

sleek

iTrader: (3)

As Lsx1 said -10 minimum on drains and -12 if you can fit it.

asubennett

iTrader: (6)

If you have the Melling High Volume pump do yourself a favor and go straight to AN12. AN10 won't cut it.

Also, ventilate the crank case with at least AN8 fittings off either the valve covers or the valley cover.

You said with the big restrictors at idle it was fine but at 4500rpm it was not. That is crank case pressure causing you problems.

I have chased these same issues. AN12 return, step back to the middle restrictor from Vibrant. I believe it's a .080 size. And ventilate the crank case...... Or - go back to the stock oil pump.

stevieturbo

You say high oil pressure....but what are you calling high oil pressure ?

You mention PCV on both valve covers...but does your crankcase actually have an ability to breathe ?

If -8 drain was fine before, then it should be ok. But you dont state whether it's a good gravity drain, how high the turbos are etc etc
But there is certainly no harm in going large on the drain.

And have you actually confirmed if there is oil passing on the turbine side ? Or just guessing ?

asubennett

iTrader: (6)

You missed most critical part of his post. AN8 worked with regular pump. Then he installed a Melling High Volume pump.

AN8 won't work any longer. Neither will AN10.

98Camarod

iTrader: (43)

I had the same pump, same feed, but used -10 drains and -10 off of both valve covers with no issues.

MEAN GTO

iTrader: (1)

Thanks for all the responses, guys! Sorry, I was wrong on the -8 returns. I do have -10 returns. The turbos are mounted behind the headlights, and gravity drain down to the top-front of the oil pan. Just under the crank pulley. All fittings for the return are 60-degree fittings and there are no kinks nor harsh bends in the return lines.

The oil pressure gauge is apparently getting up to around 90 PSI at full throttle. Not sure what the turbos are seeing since the feeds are split by a "Y", and especially now that I'm running the restrictors. I have have an oil filler breather I can put on to add with the ventilation, but not sure how to tell whether or not the PCV system is getting enough ventilation. Any solid way to determine this without having -8 bungs welded to the valve covers and start modifying things that may or may not solve the problem? I know this can turn out to be a bunch of trial and error, but anything I can do to better-troubleshoot the problem would surely be beneficial.

As far as the exhaust side of the turbo blowing the oil-- I can only go based on what the shop saw. They had the turbo blankets off and noticed the burning oil's smoke seeping out the v-band behind each turbo. I guess that doesn't mean it's not smoking from the engine, but at one point they did end up with a small oil spill under where the passenger's side turbo was sitting:

MEAN GTO

iTrader: (1)

One thing I'm going to also need to look at that I thought about today, is the oil level. Considering where my -10 return fittings are, I'm wondering if I over-filled the oil and maybe the turbos aren't draining well because of that. The car is currently parked at a friend's about 1.5 hours from me, so I'll see if he'll do me the favor of checking the oil level.

98Camarod

iTrader: (43)

If the oil level is covering up the drain, then it will make it more difficult to drain and could backup causing your problem

mkvamso

iTrader: (2)

It looks like a drain problem
My drivers side drain was just a little higher in the pan than the other side, but it caused enough of an angle on the drain to back oil up into the cartridge
Smoked like a diesel until I relocated it

asubennett

iTrader: (6)

Put the oil fill breather in. See if that helps. And yes, check your oil level.

stevieturbo

Describe how you have this "PCV" configured.

90psi is a lot of oil pressure, but if you've a single -4 split into two, chances are it will be slightly less at the turbo. And definitely less if you're restrictors in there

vertenaotne

The car is currently parked at a friend's about 1.5 hours from me, so I'll see if he'll do me the favor of checking the oil level.

MEAN GTO

iTrader: (1)

Thanks again for all of the responses guys, I appreciate the help a lot. Once I hear about the oil level I'll go from there. If it's high, then when I go to work on the car in a couple weeks I'll let some out and see how things are. I might just open -10 lines from the fittings on the oil pan and see if an oil drips out of the pan. There's one sure-fire way to know the level was too high. Otherwise, I'll just install the breather for the oil filler and see if that helps.

I'm starting to think it might be the oil level though, because I filled the oil to the "max" line on the dipstick, but when I got the car to the shop for the tuning they found that the dipstick tube wasn't seated all the way into the block (new dipstick and tube that I had to custom bend and wedge tightly between small clearances to fit). Now that it's seated all the way, I'm willing to bet that the level is above the maximum mark on the dipstick, obviously meaning that the pan is over-filled some.

Currently, the PCV system is just some 3/8" Spectre breather filters running from the 3/8" fittings on each valve cover. The oil filler is just using a normal cap right now, no breather there.

The shop was going to make a custom bracket to install my catch can, and route the breather for the catch can under the car with the other valve cover breather to somewhere under the car so I don't keep smelling the fumes of the PCV system in the cabin while driving. It was pretty strong on the drive up there, so they told me the best thing was for them to replace the oil filler breather with a standard cap and re-route the breathers to under the car somewhere, which makes sense. But maybe I'll have to live with the breather on the oil filler, or just do bigger breathers and lines off the valve covers as suggested and route those under the car.

rkreigh

another thing to be aware of with the oiling, *you mentioned restrictors in the line, 90 psi is pretty high on oil pressure!!*

you might be getting some oil seepage past the oil seals on the turbos.

anytime there is engine damage, junk can run through the oil and damage the turbo exh side housing oil seal.

I wiped a cam on an old turbo buick and sure enough, even with the fresh engine, after running the car it became a "crop duster"

usually if it clears out it can be just oil build up in the exhaust.

if the turbo seals are bad, you'll know it. it will smoke as oil dumps into the hot exhaust and get worse under boost. ask me how I know

had a friend of mine lose his oil scavenge pump on his LPE TT c5, we though the turbos were shot. it took a lap around the 495 beltway to clear all the oil out of the exhaust. the local "experts" told him it would be 7k and both turbos were shot. they were fine

not sure if there is a better way to evaluate the oil seals, but that could be your problem. the BB turbos are pretty durable and can live with less oil flow than the journal turbos, don't "over oil them"

MEAN GTO

iTrader: (1)

Yeah that's my other concern is some debris from the last failure found its way into the oil lines. I mean, the fact that it's only smoking now at heavy throttle with the smallest restrictors in would make you think it's just too much oil going in, and/or not enough going out.... but I would also thing the turbos could smoke less with these restrictors when oil contamination is the issue, because now the oil isn't pushing as hard past a gouge in the journal bearing(s) or something along those lines. Hard to say for sure yet.

And absolutely... I'll be sure to run the car for a bit to see if any changes I make that still have smoke blowing out is just residual oil or not. That's what I thought was happening when it cleared up during the drive to PA. You must not be too far from me since you mentioned I-495. Had no idea there was a Lingenfelter TT Vette around this neck of the woods at any point. Surely that is/was a nasty car.

scottywheels

I run a 45 thou restrictor on my feed to my 88mm garrett and a -12 drain, do not have a 90 for drain.

ProServ

Sounds like have the high pressure spring in the pressure control valve. That spring is designed to supply the high peak pressures needed by the camshaft phaser and AFM engines. Switch to the standard pressure spring and that should help reduce your peak pressures down to about 60 or 70 psi and that should help a little to reduce oil volume/flow to the turbocharger.

Careful going too small on the restrictor - journal bearing turbochargers need a lot more oil than ball bearing. The Vibrant kit probably has restrictors for both.

On the turbochargers, often once the seals start to leak they need rebuilt to repair/replace the seals. Get all the drain back and other issues fixed first so they get fixed and don't have to come out again.

In addition to drain size make sure you don't have a 90 degree bend coming right out of the turbocharger. Anything that can cause oil to backup into the turbocharger can cause leaks.

If it was fine for a while and is bad now this probably isn't the problem but turbocharger placement/angle can have a big impact on oil smoke/seal effectiveness. Most turbo manufacturers have a +/- window on acceptable angle and rotation for the seals to work properly.

Keep in mind the seals are dynamic seals. They only work when the turbocharger is spinning. If oil sits against the seal with the turbocharger stopped it will leak past the seal and smoke on startup (and for a while afterwards depending on how much oil leaked past the seal). For this reason make sure you don't have large and long feed lines that could hold oil after shut down and gravity drain into the turbochargers. In some applications you may even have to install a low pressure zero leak check valve in the feed lines that cracks open at very low pressure from the oil pump (a couple psi) but shuts off oil flow when the pump turns off.