HELP!! Elusive Turbo Problem

maxf15 · **Joined:** Tue Feb 28, 2012 1:30 pm **Posts:** 52

Starting a new thread..

Bottom line up front: I have a low power, low boost situation below about 2100 rpm. Codes: P0234 (low boost) and occasional P0299 (overboost) that puts the car into limp mode. Lots of black smoke associated with the low power. Mileage has dropped from 26 highway to about 20 highway (most of my driving is hwy.)

Background: I've read a ton on this site (Thank God for these posts, btw.) Based on these threads, I've done a lot of troubleshooting so far:

Checked all boost hoses (samcos installed, new turbo inlet hose)
Checked Vacuum: New Vacuum modulator, new vacuum solenoid), all vac lines tested with mighty vac hand pump and hold well
EGR delete: Installed weeks101 elbow kit with EGR blank off plate (nice kit, btw)
MAF Sensor: Brand new before I installed the elbow kit, now unplugged (ORM)
MAP Sensor: New about 5k miles ago (cleaned the old one a couple times, but wanted to eliminate that as a possible issue)
EHM: I have run EHM since 60k miles, currently at 128k miles
Checked VVT: It does seem to stick occasionally testing with a hand vac pump, otherwise good 1/2 inch of movement

The turbo still provides 21.4 psi on an uphill WOT run, and generally seems to operate well above about 2300-2400 rpm. No buzzing, burping, odd sounds; and I checked the radial/axial play, both seem to be about 1/16" or better (not measured, just by feel).

Is there a good way to clean, lube, or otherwise replace the vacuum vane motor/actuator or ensure the vanes are clean and aren't sticking? :?:

It's my last hope before dropping the bucks on a new turbo. Plus I'm running out of $$ !!!

Any help would be appreciated.

papaindigo · **Posted:** Tue Jul 01, 2014 3:34 pm

That 1/16" of play worries me a bit. The solid turbos I've seen and felt have just a tiny bit of fore/aft play (like the thickness of a piece of paper or at most a playing card) and only the slightest hint (I can barely feel it but not see it) of side to side play. In any case there should be no sign of contact between the vane tips and the sides of the housing.

P0299 is BOOST PRESSURE SENSOR POSITIVE DEVIATION. There has been at least one report (viewtopic.php?f=5&t=61240) of this being caused by a melted vacuum line by the firewall under the coolant tank.

Sticky variable vanes could cause this problem. The traditional fix is an Italian tuneup (on hot engine do several full throttle runs, smoke and all, up a slight to modest slope to raise EGT temps and burn off carbon). In extreme cases I've heard of cleaning with oven cleaner but don't know the procedure.

DOC4444 · **Posted:** Tue Jul 01, 2014 11:09 pm

Sorry, but your turbo is shot if there is ANY axial play. Turbo failure can lead to engine failure in about 45 seconds. Replace turbo before starting. (ID Parts has them at a good price.)

DOC

geordi · **Posted:** Wed Jul 02, 2014 1:09 am

Doc, I think you have that backwards. Axial is end-to-end or front-to-back as the turbo is installed in the engine - A small amount of play here is normal. 1/16th of an inch could be more than normal, but not outside the realm as he states he didn't actually measure it. Any vane contact would be a full stop deal breaker however.

Radial play is side-to-side (across the RADIUS of the rotation) and this is where you want barely-anything-perceptible because any play here means that the turbo sleeve bearing is not tight enough to hold and keep the oil cushion in place.

It sounds like sticking vanes to me - the overboost code is a giveaway on that one. If the modulator is good and the vacuum is good - did you replace the air filter on the bottom of the modulator so it has the ability to "relax" the boost when it wants to? The vacuum motor on the turbo needs to rapidly push down on the rod when the vac is released. If the rubber isn't flexible enough or the vanes are jamming in the closed position, this could cause the overboost conditions. Slow to build boost in midrange also suggests a vane problem. Luckily, this is something that COULD be rebuilt (only the center cartridge cannot be properly rebuilt) but it may not be worth the effort versus just replacing with a new turbo.

IDparts should be your source for the turbo. Anyone that asks for a core of the old unit - RUN AWAY, they are selling you a rebuilt that will have dubious quality. Garrett still does not offer rebuild kits for our VNT turbos, because the center cartridge is so precisely balanced.

racertracer · **Posted:** Wed Jul 02, 2014 4:27 am

Sounds like sticky turbo vanes to me.

Bring the engine up to peak temp and put the pedal to the metal..... you should get turbo response back in about three tries.

If the overboost code returns reset the code with your code reader and do it again until all the stuck on carbon is gone.

If the vacuum modulator is sluggish and the rod hardly moves then for sure your vanes are filled with hard carbon preventing the turbo to function properly. You need to super heat that crap and blow it out.

Nothing wrong with the turbo.... if you drive this vehicle like an old lady and never give the go pedal a run for its money, then for sure your turbo will get sluggish.

So get the engine super hot and floor it, you will be in warp speed heaven very shortly and report back.

Been there done that on 2 CRD's .... A trick I was taught by Keith at GDE.

DOC4444 · **Posted:** Wed Jul 02, 2014 6:43 am

http://www.nationalprecision.com/miniat ... l_play.php

My understanding is that axial play is "end play" and that ANY of that on our turbos is an indication of imminent failure. I have a brand new turbo on the shelf. It has barely perceptible radial play, which apparently is normal (and NO axial play).

DOC

WWDiesel · **Posted:** Wed Jul 02, 2014 7:12 am

You stated you have a mighty vac hand pump? With the engine OFF, remove the air inlet pipe to the turbo so you can watch the vanes on the turbo. Connect the mighty vac to the variable vane operator at the turbo and pump the mighty vac while watching the vane movement. It should be very smooth from closed to wide open! If any sticking is observed, spray some good penetrating oil on the operator linkage and work the vane movement back and forth using the mighty vac.
You can also connect the mighty vac to the plastic pipe that goes to the turbo back of the coolant tank at the vane control solenoid connection over at the fender and pump the mighty vac and observe vane movement. Doing this will also check the status of the plastic pipe going to the turbo vane operator. If you cannot build up any vacuum from the solenoid end, then the pipe is bad. Replace it!
Good luck and keep up posted as to what you find.
:JEEPIN:

maxf15 · **Joined:** Tue Feb 28, 2012 1:30 pm **Posts:** 52

Thanks for the replies.

geordi – I only replaced the modulator and solenoid, not the vacuum filter. But there’s good flow through it.

papaindigo, racertracer - Italian tune up didn't fix it. Tried it a dozen times on the way to work (I commute about 30 miles). It blew out a lot of soot, but the low end sluggishness and black smoke remained.

WW Diesel - Tonight I’ll try the mighty vac procedure. If there are any issues I’ll likely pull the turbo and do the oven cleaner treatment mentioned elsewhere.

DOC444 – Going to check the play again while I’m in there and let y’all know what I find.

I’m ready to have that zippy pedal back… not to mention the mileage.

Cheers!

maxf15 · **Joined:** Tue Feb 28, 2012 1:30 pm **Posts:** 52

Dropping back to punt...

I've got a new OEM turbo and oil feed line on order from IDParts.

(While I was looking I saw Sasquatch was running a sale on their elbow kit.)

I'll post an update after the install...

Thank for all the replies. That's what makes this site so good, folks helping each other out.

DOC4444 · **Posted:** Thu Jul 03, 2014 9:10 pm

Get the new style oil return tube while you are at it and an extra gasket for the top of the return tube and an extra grommet for the bottom. Install return tube before putting the turbo support bracket back on.

DOC

maxf15 · **Joined:** Tue Feb 28, 2012 1:30 pm **Posts:** 52

Shheeewwww!!! Got the old turbo off without breaking any studs. What a flippin awful place to put those exhaust flange bolts!!! That engineer should be tarred and feathered and then drawn and quartered. Just sayin'.

Well, with the turbo out I was able to check play again. The axial play is excessive. My best guess is it was rubbing somehow and not spinning up without a ton of air going through it (> 2000 rpm-ish). Funny I never heard any noises from it. I'm a bit concerned I'll put in the new one and still have the problem. If so I'll be out of ideas.

The new turbo should be here Monday or Tuesday, so we'll see. I'll post an update after the install.

DOC444 - I'm not familiar with the new style oil return. What does it do differently than the old one? Got a part number/source?

Cheers!

diesel_guy86 · **Posted:** Sat Jul 05, 2014 8:10 pm

The new style has a braided flex section in it to give it some wiggle room. Factory line was a solid steel ridgid tube.
I've had my manifold on an off about a dozen times, its not that bad, helps to have a universal joint.

geordi · **Posted:** Sat Jul 05, 2014 10:50 pm

Congrats on getting it off without breaking any of the studs.

May I suggest, do not use the copper jam nuts when you reinstall it. Use normal threaded grade-8 nuts with lock washers. The copper nuts heat up differently than normal steel, and will bite into the sides of the studs as they heat cycle. There is an infinitesimally small chance that regular nuts would loosen in normal operation, but as nothing in this area rotates or moves once it is locked down... They chose the copper for reasons I cannot fathom. What I DO know is that you will be fighting those nuts for every turn, in that extremely cramped location. Normal nuts can be spun down by fingers until they contact, then wrenched snug.

Think about changing those studs while you have the opportunity. NAPA sells a stud-biter removal tool, but PB blaster is your friend here. Vice grips may also be of great help. Those studs are NOT graded hardware, they are VERY VERY VERY weak and the chances of snapping one off are pretty good. You don't want to do that. Replacement grade 8 studs can be found easily in your auto parts store.

diesel_guy86 · **Posted:** Sat Jul 05, 2014 11:03 pm

My guess is they used copper so that it wouldn't rust to the steel stud. The nuts are "crimped" at the factory to make them bite the threads harder, making it a lock nut but without the normal nylon ring. A few times of use and they thread on and off like normal nuts.

papaindigo · **Posted:** Sun Jul 06, 2014 8:03 am

"New" style oil return line is at http://idparts.com/catalog/index.php?cP ... 651b860b7e scroll down to end of list for line and grommet

X2 on just use regular nuts not the jam ones and same for replacing studs although grade 5 will do (certainly better than the junky OEM ones)

maxf15 · **Joined:** Tue Feb 28, 2012 1:30 pm **Posts:** 52

Maybe I'll brave it if the studs seem like they'll come out easy, but I'm afraid of snapping them off trying to get them out and I'm not equipped to drill and retap.

Anyone have the specs? Thread size/pitch and length; or maybe a NAPA part number?

papaindigo · **Posted:** Mon Jul 07, 2014 12:05 pm

PB blaster or something similar and lots of soak time is your friend if you try to remove the studs. In my specific case 2 studs broke when removing the nut - one with enough length left to grab with a stud remover and the other with just enough left to grab with vice grips and work out with the application of a bit of heat. The 3rd had to come out - needed a longer stud in that position for the GDE Stage II turbo. The 4th we (geordi and I) just left in place.

I don't recall the length or thread pitch but I think it takes a M8 bolt, check the ones you removed. In any case it's an over the counter metric stud size. As I recall we got replacements at like AutoZone or some such (not NAPA although I'm sure NAPA would have them). I think we got grade 5 not 8 - even 5 was way better than stock.

WWDiesel · **Posted:** Mon Jul 07, 2014 9:53 pm

Standard thread pitch for 8mm bolts/studs is 1.25mm. Fine thread is 8mm x 1.50mm....
Any good hardware store like ACE should have them in stock...

geordi · **Posted:** Mon Jul 07, 2014 10:38 pm

PB blaster, tap the end with a hammer to put some high freq vibrations through the threads... I've also heard of using a 50/50 mix of transmission fluid and acetone as the wonder-penetration-oil option. You will know how they will turn if you try with vice grips. Don't just go for it in removal-direction (lefty loosey) only... Turn them in small amounts in both directions once they start moving, it will help the oil get deeper into the threads - of course, keep adding more as you are turning.

maxf15 · **Joined:** Tue Feb 28, 2012 1:30 pm **Posts:** 52

New turbo arrived from ID parts today. I installed it with new gaskets, and a new oil feed line (my old oil drain tube already had a flexible part to it, so I reused it.

I pre-lubed the turbo through the oil feed port, and gave it a 5 minute warm up after completing the install. Then took it on a very docile test drive for 4-5 miles.

Unfortunately... No change. Ugh. :banghead:

The libby still has very low power and low boost (still throwing the code) under about 2100 rpm.

OBTW, I changed the fuel filter and air filter while under the hood just to eliminate a couple more things.

What else is there? Intercooler maybe? I guess a leak in the intercooler itself would allow boost to leak, right?

Any other ideas?

HELP!! Elusive Turbo Problem

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