87 300TD garret turbo issues... advice needed - PeachParts Mercedes-Benz Forum

locry · #1 05-03-2010, 01:39 PM

i had my IP calibrated recently , but i'm not happy with the result...i was expecting a night and day difference in terms of power. The car does idle smoother and starts easier, so i guess the IP job went well...injectors weren't touched btw... will have them balanced some other time...

anyway, these are the symptoms... off the line the car isn't that sluggish, and not too fast either... it feels just right so no issues there... my problem is when the car starts to pick up speed, it feels choked... when you step on the accelerator it SLOOOOWLY picks up speed... so i am clearly either not getting boost or enrichment...

don't have a boost gauge so i did the preliminary checks concerning plugged ALDA lines etc... all is clear

next I checked to see if the turbo vanes spin freely (engine off ofcourse)..this is where i'm having issues... with steady finger pressure the turbine spins freely up to a point then starts to stick JUST BARELY...then spins freely again... so when you try to spin the turbine with enough force it won't freewheel an entire revolution... is this a STICKING turbo issue? or is this normal?

Anyway... i managed to remove the turbo this evening...what a PITA!!!!!
the hosing, external, was all gunked up... i was thinking of opening it up and cleaning it myslef but after reading a ton of threads I might just opt to have it inspected/rebuilt/cleaned just to be on the safe side.

so before going ahead and bringing it to a shop... anything I should check on my own? should i just DIY it and just clean the thing?

scottmcphee · #2 05-03-2010, 02:56 PM

Wait: check your wastegate, and get a gauge and check your boost first before you blow that money.

To give you an idea of turbine resistance, I have to push my turbine around by finger to keep it moving... doesn't spin freely at all... Let go it stops. I used a thin wooden stick, a coffee stir stick, to move the turbine and the stick flexes quite a bit before turbine begins to budge. The turbo is not sprouting oil leaks either. I don't know why it's relatively stiffer than what I'd expect. The car has been babied on oil changes, never abused. 200k miles on the original turbo.

But I get great pressure out of this turbo, here's how:

I added an aftermarket manual wastegate controller for $20. Splice it into the wastegate line. Adjusted it for 1 bar. Made a world of difference. Without it, I could only pull somewhere between .6 and .7 bar under full load / full pedal and the car moved faster and everything... but topped out at maybe 140km/h. Ho Hum dee dum... The reason is weak wastegate spring.

The controller proves I have a good wastegate valve seal, because I can get multi-bar pressure out of this thing. If you can just keep the valve from opening too easily. Hence the controller, blocks off pretty much all pressure to the wastegate until it wants to let go first, then bang the wastegate flies open at that limit. I could too easily dial up 1.5 bar and nearly **** myself thinking I'd blow up the car pulling out of my driveway, before jumping out and toned it down.

You shouldn't have yanked the turbo out so quick. Check your boost pressure / manifold pressure under full boost. See what you get on a real drive, not just rev's in the garage... you need load.

Maybe you have a soft wastegate spring, like I do. You can compensate for this really easy, like I did. But you'll want to put and keep a boost gauge handy and in eye-shot on the dash, like I have.

The downside without a gauge is you have NO IDEA of what boost you're pushing. There is no by-the-seat indicator or performance increase measure for over-boosting the car. You only need as much air as you have fuel, your stock and well tuned IP is fuel limited so the extra air is just hot gas you don't need in the cyl because it's not adding any value beyond a certain point. That point is about 1 bar.

Brian Carlton · #3 05-03-2010, 03:14 PM

Quote:

Originally Posted by scottmcphee

You shouldn't have yanked the turbo out so quick. Check your boost pressure / manifold pressure under full boost. See what you get on a real drive, not just rev's in the garage... you need load.

Agreed.

A boost gauge is far less costly than a rebuilt turbo ($375).

locry · #4 05-03-2010, 09:52 PM

hehe, ok... i'll put it back on.... will clean the externals while i'm at it... the turbo housing is soooo gunked up where could the build up have come from?

the oil return tube that's resides under the turbo is just supposed to slide in?

there's a pool of oil at the intake side of the turbo... how much is too much?

oh yeah... i had a hard time yanking the turbo out of the engine bay because the mixer housing was in the way, the cone/tube was lodging itself at an angle... is there an "elegant" way around this? wasn't comfortable using force to remove it.
and... there was this one bolt that gave me trouble which made the job soooo difficult, it was the 2nd bolt at the front bracket, which i accessed from under the car... didn't have much leverage and was feeling my way... no line of sight whatsoever, can i skip installing that bolt?

locry · #5 05-03-2010, 09:55 PM

with the turbo on the bench what is there to clean? can i spray degreaser through the turbine? can i somehow clean the wastegate flapper or shouldn't i touch anything and just clean the housing... there's no side to side nor axial play at the shaft so i feel confident about that.

locry · #6 05-03-2010, 10:00 PM

@Scott... will try to check my wastegate system first... might not have to resort to an aftermarket controller... but that does sound like a plan. I'm not sure if my wastegate actuator is working, it's hard to "actuate", can't get the rod to move... though i did read that it is almost impossible to budge externally... thanks

scottmcphee · #7 05-04-2010, 02:38 PM

There are oil stains and soiled metal around my turbo and its various parts too. Degrease and wipe while it's off car.

IIRC the oil tube is held in place by the turbo being mounted, you sorta have to wedge it into place as your mounting the turbo. Now's a good time for any seal replacements in the area.

I found it was easier to do turbo R&R with the exhaust heat shield removed from the engine bay, the thing that keeps your coolant and air filter apart from the exhaust bits. Maybe you can get at all the bolts/nuts better this way.

How much oil is too much oil spilling out of a turbo? If you're burning blue because of it, or if the engine continues to run after you turn the key off because it's burning motor oil sucked through the turbo, or if you're leaving drips on the garage pad, that's too much.

Any guck inside the air tubes comes mostly from EGR. Remove EGR valve assembly for inspection then forget to reinstall it, use a blocking kit after you misplace the EGR. I think motor oil sucked through the turbo actually cleans up the intake innards somewhat.

I was tempted to clean the compressor turbine off - one blade of it was soiled but all the rest were shiny but I skipped using any cleaners inside the turbo, only wiped the outside. Sometimes its better to leave well enough alone.

You should be able to see some of the wastegate valve resting against its seat. Should not be ajar. You might be able to use a small mirror or feeler to see if the part you can't see is chipped or cracked or not seating for some reason. You can't move a wastegate by hand very easily. You could apply pressure to the orifice and watch it move though. Use a mityvac pressure pump model for that, or a very light touch on an air compressor gun that is toned down at its output will do for a quick experiment. Only need 14 psi remember!

For $20 I found the boost controller (just a piece of plumbing, really, with a spring and ball inside) was the ticket for my softening wastegate spring. Takes about 2 minutes to install, and a few test runs to set. 1/2 hour all done. The trick is find one with the right hose barb size on it, MBenz is odd from the industry normal on this hose for turbo wastegate.

The net result is you get the boost you want, can get back up to factory spec (about 0.9 bar), or higher if you have fuel over-delivery rigged up, or wanna add propane one day! Also, with the external boost controller, you get slightly quicker spool up to full tilt, which may result in slightly quicker car if you're really racing around. But overall, this is not really a performance mod other than to get back to stock levels.

locry · #8 05-05-2010, 04:05 AM

yeah baby! excellent tips!

quick update... i guess from your description my oil situation is normal.

soooo.... i reinstalled my turbo as per this thread's advice... i also had a trap-ox replacement pipe fabricated (my old one was a gutted trap-ox... re-call not applicable here)... i errrr... misplaced my EGR and blocked off the hole in its place.

as per forum advice...for testing/offroad purposes... oh yeah, i also checked the wastegate and it was seated properly, opened and closed easily enough with the actuator disconnected.

anyway... install went pretty well...here's my concern:

the engine seems to be more responsive (tested throttle/car in PARK)..but there seems to be LOADS of soot/carbon coming out the tail pipe... as in TONS of carbon... am I only now enjoying a working turbo after replacing the gutted trap-ox and blocking off the EGR?...or is it something else? i haven't tried driving it yet i want to check with you guys first. thanks much appreciated

bobodaclown · #9 05-05-2010, 05:49 AM

Turbo must be checked with a load on the engine. (eg driving test on the road) You can pick up a boost gauge 0-20 and tie in with a "T" fitting off the manifold the line that goes to the ALDA to ensure your getting proper boost. Part stores have a combined VAC/PSI gauge its about 30 bucks. It might only go to 10 but it's in the ball park, about 8 feet of of 1/4 inch hose and a T-fitting (plastic will work). you'll need to cut a short piece of hose (about 4 inches) to connect the T fitting in line with the line that feeds the ALDA.

locry · #10 05-05-2010, 08:17 AM

will get a boost gauge sometime this week hopefully..

ran the car earlier... getting smoke when i mash the pedal... car doesn't "GO" though...
...when in neutral... when i rev the engine a few times up to abt 2500-3000 it smokes like hell

scottmcphee · #11 05-05-2010, 09:14 PM

If your ALDA is removed, shimmed up too high, or broken, black smoke ensues at off-boost RPM when you goose it. That'd be normal. After about 2500 RPM if you still have smoke, it's not the ALDA's fault.

Black smoke should stop when you're driving (got load) and turbo is producing output and you're feeling power. If it still smokes in these conditions your finely tuned IP could be too rich, your turbo is not producing enough air, or that's some other kind of smoke... like that oil from the turbo is more chronic than you think and it's dumping oil into the exhaust side as well for a smoke show.

locry · #12 05-06-2010, 05:38 AM

quick update... afaik the ALDA has never been touched... the seal on top is still intact...

anyway... with a plugged exhaust frame of mind, i tried banging on that resonator thingy near the rear diff with the engine idling... (i do not have a CAT anywhere near the engine, the resonator thingy is the only thing between the rear muffler and the turbo), carbon and soot came out with every bang... i'm guessing its all plugged up... what is it anyway?

i drove the car after that and it did improve a bit, now i could very clearly hear the turbo working as i could hear a slight wiiiiiiisssssshhhhhh that coincides with engine revs... the car now accelerates a bit easier, though i feel there's more to be had... i'll be replacing that resonator thing with a straight pipe tomorrow, or have it gutted... will report back with the results.