Bad turbo in my 124? - PeachParts Mercedes-Benz Forum

muleears · #1 03-04-2008, 06:57 AM

My car has what I thought is a bad turbo. I even had an indy tell me so. The car has virtually no acceleration. This is the 87 124. It went from 12sec. 0-60mph one day to 30+ within two days. No noticeable oil consumption (Rotella 15-40) Some minor grey smoke on startup. Have checked for plugged vac. lines. Checked and cleaned overboost valve. Alda was adjusted 1yr. ago with good results. Hooked pressure gauge up to nipple on drivers side of IM and 0psi. When I tested the boost I could only accelerate up to 35 but I thought at least some boost would register. I will try again today and floor it up to 60mph. It seems to get a little better as the car warms up. Any other tests or conclusions?

BJ300SDL · #2 03-04-2008, 06:59 AM

If Your Turbo Has A Waste Gate That Is Stuck Open That Could Possibly Cause The Problem.

muleears · #3 03-04-2008, 07:17 AM

Do you know if mine is a spring or vacuum controlled wastegate?

bobodaclown · #4 03-04-2008, 08:09 AM

Spring Pressure/Actuated see pictures....

Should wastegate fail, a pressure switch installed in intake manifold closes an electrical circuit, energizing a switch-over valve. This valve closes pressure line to intake manifold and simultaneously open aneroid compensator to atmosphere. This reduces fuel quanity being injected.
Pressure switch only functions when intake manifold boost pressure reaches 16psi.

muleears · #5 03-04-2008, 10:01 AM

Quote:

Originally Posted by bobodaclown

Spring Pressure/Actuated see pictures....

Should wastegate fail, a pressure switch installed in intake manifold closes an electrical circuit, energizing a switch-over valve. This valve closes pressure line to intake manifold and simultaneously open aneroid compensator to atmosphere. This reduces fuel quanity being injected.
Pressure switch only functions when intake manifold boost pressure reaches 16psi.

So if the wastgate spring fails, the wastegate would be open (I assume the spring holds it shut)? The performance of the car could be from lack of fuel I suppose. How do I check the wastegate for failure?

2.5Turbo · #6 03-04-2008, 11:19 AM

Check your filters before digging too deep. A plugged filter could restrict the fuel enough to prevent boost from building. 30 seconds sounds really slow for a 603 NA (which what your engine essentially is with no boost). The 5-cyl 602 in my 124 was giving me 18 second 0-60's with the wastegate held open by a bad transducer, so I would guess a 603 with a similar situation would be a little faster than 18.

DrewKeen · #7 03-04-2008, 11:23 AM

I was getting 30 sec times in mine and one of the lines going from the IM to the ALDA was plugged. Also take off the nipples on both ends and clean them and then try to blow through the lines and the overboost solenoid.

ConnClark · #8 03-04-2008, 11:39 AM

If you have an 87 and a Garrett turbo, then the wastegate has a actuator is connected by a rod to a lever just behind the turbine housing. The lever should be held by the actuator towards the compressor side of the turbo. when enough boost pressure is applied the lever gets pushed away from the compressor side of the turbo opening the wastegate.

Remember, boost helps build boost. So a large boost leak such as a broken ALDA line can kill all boost.

sixto · #9 03-04-2008, 11:54 AM

What I would do:

- make sure the wastegate actuator rod is attached to the wastegate flap lever.

- check the turbo impeller. You should be able to spin it with your fingers. There should be minimal radial play and absolutely no perceptible axial play.

- replace fuel filters.

- blow through the overboost solenoid. Air should move freely through the solenoid.

- blow into the manifold boost signal fitting. Air should move freely through the fitting.

- route a line directly from the manifold fitting to the ALDA and go for a spin.

- remove the ALDA and go for a spin.

- remove the plug on the #1 exhaust runner. If this helps performance even slightly, the oxidation catalyst is gunked up. Or is the trap still in place?

- open the ARV and check if the plunger is deformed or dislodged. This alone can't account for 30 second 0-60 times.

Sixto
87 300D

muleears · #10 03-04-2008, 12:29 PM

Quote:

Originally Posted by sixto

What I would do:

- make sure the wastegate actuator rod is attached to the wastegate flap lever.

- check the turbo impeller. You should be able to spin it with your fingers. There should be minimal radial play and absolutely no perceptible axial play.

- replace fuel filters.

- blow through the overboost solenoid. Air should move freely through the solenoid.

- blow into the manifold boost signal fitting. Air should move freely through the fitting.

- route a line directly from the manifold fitting to the ALDA and go for a spin.

- remove the ALDA and go for a spin.

- remove the plug on the #1 exhaust runner. If this helps performance even slightly, the oxidation catalyst is gunked up. Or is the trap still in place?

- open the ARV and check if the plunger is deformed or dislodged. This alone can't account for 30 second 0-60 times.

Sixto
87 300D

The rod seems to be attached but I can't move it by hand.

Have not checked the impeller.

Filters changed (acceleration is linear not like driving in a stiff wind.

Blew through/cleaned all lines/fittings and overboost valve.

Ran a line from IM nipple to alda, no change.

Have not removed alda

Removed plug at number one, noisier but no more power. No trap.

ARV/EGR disabled years ago.

Obviously I had done some of these things before my post this morn. I just couldn't remember until you refreshed my memory.

I guess my next steps are: check the impeller and remove the alda.

Would a bad alda cause that large a power loss? I have driven the car previously without the alda and it smoked ALOT.

Thanks for the help. I know we can figure it out.

sixto · #11 03-04-2008, 01:05 PM

Quote:

Originally Posted by muleears

Obviously I had done some of these things before my post this morn. I just couldn't remember until you refreshed my memory.

I just like to ramble

The ARV in my SDL had a deformed plunger. It was leaking boost from the compressor outlet to the compressor inlet even with the vacuum hose disconnected. I haven't heard of anyone else having this problem.

And here's more rambling -

The ALDA puts pressure on a plunger atop the IP to generally reduce fuel. As boost builds, the ALDA piston retracts allowing the IP plunger to rise and allow more fuel. You might think of it as a secondary throttle. With the ALDA off the IP, you open the door to maximum fueling even without additional air charge. The IP introduces more fuel than the engine can burn and thus have smoke if you applying pressure on the pedal more quickly than the engine can build revs.

I don't know if you can do a visual test of the ALDA by applying pressure and watching the piston retract. Since you have to remove the ALDA to do such a test, it's simple enough to go for a drive with the ALDA off and assume the ALDA is stuck or has a leak if performance improves.

You can use the ALDA off a 617 if you need a replacement. Or bum one off the many folks who have eschewed the ALDA.

Sixto
87 300D

muleears · #12 03-04-2008, 01:45 PM

Thanks Sixto, I want to say that this problem started about the time I had the alda off. Could there be a correlation? Like maybe I broke my alda putting it back on? I'll take it off tonite and see what happens.

I may be off on the 0-60 times but not by much. I'll check it on the way home and see for sure.

muleears · #13 03-04-2008, 03:50 PM

On the ride home today I did some more 0-60 tests, all tests are with the AC off:
Accelerating with just enough foot to keep accelerating 32 sec.

Foot to the floor, kickdown engaged 24 sec.

Foot to the kickdown (not engaged) 28 sec.

It seems to take forever to get the last 1000rpms in each gear. from 3500-4500 takes several seconds just by itself. It also lurches forward when it shifts.

Moderate black smoke on second two tests, little smoke on first.

I will investigate the other things we talked about this afternoon.

muleears · #14 03-04-2008, 05:55 PM

Well, I found whats wrong. After trying a few other things I took the air snorkel off the front of the turbo to check the impeller. First thing I noticed was that the fins were nice and bright, I also noticed some oil pooling in the bottom. Then I noticed the STONE wedged into the front of the impeller. Pic 2 is of the stone next to a 8mm wrench. The front of the impeller was ground off, thats why it was so shiny. So I guess my search has ended, problem found, yet to be solved. Fortunately I have a spare turbo. Pic one is a poor shot from my phone through a mirror of the front of the impeller. If you look closely you can see the shiny vanes and the stone at about 3 o'clock. Thank you all for the help. I now know what route to take. But answer me this... how in he?? did the stone get there? I don't run without an air cleaner or any part of one. Do you think some unsavory indy put it there??? Has anyone ever seen a rock that size in a turbo?

sixto · #15 03-04-2008, 06:24 PM

Is it definitely mineral? It's not a chunk of somthing that formed near the EGR valve and dropped into the compressor?

Sixto
87 300D