Turbo Dead - Page 2 - PeachParts Mercedes-Benz Forum

oldiesel · #16 09-30-2010, 10:44 AM

I agree on black smoke up hills would logically make you think plenty of fuel,so the lack of boost would be the culprit.My 87td had the exact same symptom,heavy black smoke just to climb the ramp to the interstate which is not very much of a hill in Florida,not much power on the level, i could eventually make 80mph.Once i got it home i checked all the usual suspects,plugged lines,switchover valves etc; to no avail.After reading alot on here i removed the ALDA and instantly a totally different car,the difference was obvious just backing out of the yard.I did find that the seal in the alda was no good and found an o ring that looked like it would do the job,reassembled the ALDA and pressure tested it with a bicycle pump and it does move when pressure is applied but i have not yet put it back on,i am not sure i will ever put it on.I am presently about 1500 miles into a 2200mile trip towing a small camper and staying off of intersates just been thru the mountains of western N.C.some of the grades were pretty long and steep but by using 3rd gear alot and a little cautious with the power pedal ii did not see any serious smoke so no reason to put it back on that i can think of. Try it you will like it! Don

scottmcphee · #17 09-30-2010, 10:57 AM

OP: the previous post beat me to the punch... Your thoughts on the ALDA are correct, when it is functional. When the seal breaks it fails and can behave opposite to what you'd expect: more boost pushes plunger DOWN instead of up, cuts fuel, you no-go.

Like I say, pop the ALDA off the IP completely while you're diagnosing a power problem. Then decide later if you ever want to put the ALDA back on.

winmutt · #18 09-30-2010, 11:04 AM

It sounds to me like your wastegate is stuck.

babymog · #19 09-30-2010, 01:01 PM

Smoke and no power? Definately rules out the ALDA in my mind, have you checked your air filter for a mouse home?

oldiesel · #20 09-30-2010, 02:07 PM

Babymog
That was my thinking exactly,my experience with other diesel engines where we had similar devices we just called "smoke stoppers"had me convinced that the problem was too little air and my neighbor who is a retired heavy otr truck mechanic agreed,we did alot of head scratching. Reading whatever i could find on here led me to try removing the ALDA its free and simple to try and i had not found anything else,all i can say is it worked! Neighbor is still wondering why,says it makes no sense at all and i agree with him,but i am not the only one who has experienced this and i have given up trying to understand it. It Worked and still runs great.When i get some time later this winter i may try putting the darn thing back on just to see if with the o ring in there so it holds pressure it will be as good with it as it is without. Don

LoosBenz · #21 10-09-2010, 08:54 PM

I had some time to work on the car today starting here:

Found it in the intake hose in the fender. Score one for Jeff, but as optimistic as I was, removing it did little to improve performance.

Next,I took a line straight from the manifold to the ALDA. I didn't see as much smoke on hills, but no power increase.

I pulled the ALDA loose. Big difference in off-the-line acceleration. Once moving, things fall apart, again. Power about the same as before, but horrendous smoke. Seems the ALDA was doing its job, but she's just not getting enough air.

I'm going to pull the wastegate line tomorrow and see what happens.
Referencing the picture below, is this where I would expect the wastegate lever to be when in the closed position?

sixto · #22 10-09-2010, 09:32 PM

That picture looks just like mine.

Can you tee a boost gauge into the line from the manifold to the ALDA?

Are you daring enough to try the car with the downpipe disconnected from the turbo? If performance improves, maybe the oxidation catalyst is clogged.

Sixto
87 300D

LoosBenz · #23 10-09-2010, 11:18 PM

Yeah, I'm going to tie in a boost gauge tomorrow (hopefully) while I'm playing with the wastegate hardware. Opening the exhaust was kind of a last resort in my mind. I can see where it could be the culprit, but it sure is blowing a lot of exhaust out for being plugged.

sixto · #24 10-09-2010, 11:22 PM

Have you tried to spin the turbo impeller by hand?

Sixto
87 300D

LoosBenz · #25 10-09-2010, 11:29 PM

Yup, and there was considerable discussion earlier in this thread on how it should "feel" while turning by hand. At this point, I'm guessing it's ok, especially since I saw it turn on its own while the engine was idling. Granted, just because it is turning at idle, doesn't mean it is spooling up properly at higher rpms/load, but I should know more after running more tests tomorrow.

LoosBenz · #26 10-10-2010, 06:52 PM

Still no love. I'm out of time for this weekend.
So, what I've done this weekend is:
1. removed ALDA
2. disconnected EGR and blocked hose
3. disconnected Air Recirculating Valve and blocked hose
4. disconnected wastegate line and blocked hose.
5. connected gauge to manifold port. Got -.25psi at idle, +.45psi max on the road.
Road test after each item.
Same good pull off-the-line. Same bogging and smoke on hills and moderate to heavy acceleration.
Guess I'll plan on pulling more stuff apart.

winmutt · #27 10-10-2010, 09:32 PM

If you are only getting ,45 and the turbo spins you have a cracked manifold or stuck open wastegate. You are losing alot of air somewhere.

sixto · #28 10-10-2010, 09:32 PM

How about the plug on the #1 exhaust runner? That'll reduce flow to the turbo but should help if there's an exhaust blockage.

Have you seen the fuel pressure threads? Maybe your check valve/regulator is opening prematurely so there's not enough pressure to sustain load. Maybe your lift pump isn't putting out enough volume. It's starting to sound like a fuel or IP problem.

Sixto
87 300D

vstech · #29 10-10-2010, 10:16 PM

on my TD, I have a cracked connector between #2 and #3, and I sealed it up to get additional exhaust to the turbo.
when I pulled the airfilter box I noticed the cold air intake has a throttle of sorts... what is it, and how does it open and close? could it be closing in the OP's car limiting the intake of air for the turbo to pressureize?

LoosBenz · #30 10-10-2010, 10:54 PM

Quote:

Originally Posted by winmutt

If you are only getting ,45 and the turbo spins you have a cracked manifold or stuck open wastegate. You are losing alot of air somewhere.

There is no evidence of a crack. I'm pretty sure I'd see smoke under the hood if the exhaust manifold was cracked enough to allow that kind of leak. I'm starting to think maybe the wastegate fell off of its pivot.

Quote:

Originally Posted by sixto

Have you seen the fuel pressure threads? Maybe your check valve/regulator is opening prematurely so there's not enough pressure to sustain load. Maybe your lift pump isn't putting out enough volume. It's starting to sound like a fuel or IP problem.

Sixto
87 300D

Still planning to separate the exhaust pipe from the turbo (if nothing else works) in case the cat is plugged. I don't think fuel is the issue because it REALLY starts to smoke under heavy acceleration. Still makes me think lack of air.

Quote:

Originally Posted by vstech

on my TD, I have a cracked connector between #2 and #3, and I sealed it up to get additional exhaust to the turbo.
when I pulled the airfilter box I noticed the cold air intake has a throttle of sorts... what is it, and how does it open and close? could it be closing in the OP's car limiting the intake of air for the turbo to pressureize?

THAT'S something I'd really like to know. Pulling my filter box and checking out this device may be my next step.

Thanks again, everyone!
Louis