As far as I know, no you can't - that line is connected back to the EDS. But, having said that, and having a few whiskeys, that shouldn't be a problem. Except, it introduces another point of failure. And you don't need to. There is another hole right next to that one with a standard NPT thread.

I used a standard compression fitting (1/4" I think) from lowes and connected it back to the wastegate actuator. Used a compression fitting so it wouldn't come loose. And used Viton hosing becuase it can take some heat, but I'm sure there are better hoses to use. The point here is to make sure the hose between the actuator and the actual pressure is not interrupted so you don't get overboost.

Anybody know a good hose to use? My only worry is that this system has a single point of failure and is non-failsafe. Anybody else a worry wart?

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1983 240D Silver/Blue "Sadie", unknown miles. 100k miles on WVO single tank, converted to 2 tank about 10k miles ago, FPHE, Injector Heaters, Aux Fuel pump. Alcohol/Water injection. Frantz oil bypass filter
1992 300D 2.5 Turbo Green/Tan "Jade" 267K miles Stock.
1992 300D 2.5 tan/tan "Rocky" on 2 tank WVO. Pressure actuated Turbo "rat's nest" surgery completed. 197k miles

'Will not the overboost protection circuit still disable the ALDA from Fuel enrich
when the pressure goes over specs?
Overboost is not funny...BUT without fuel it's less dangerous.

(Note to whichever of my few remaining synapses is in charge...Boost Gauge in Former Ash Tray next to Pyrometer)

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'84 300SD sold
124.128

I've lost track of this thread but engines with vacuum controlled wastegate do not have an overboost switchover valve along the ALDA signal line. It's really easy to install one.

Sixto
87 300D

Correct. The overboost protection (pressure switch & switchover valve for the ALDA line) was deleted, I believe starting in the 1992 model year. The switch engaged at (IIRC) 1.15 bar, ±0.1 bar, or something like that (approx 15-18 psi). Funny thing is, with the wastegate disabled, my cars couldn't exceed 18 psi anyway. Maybe that's part of why MB removed it?

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Check out my website photos, documents, and movies!

Isn't oveboost protection incorporated into EDS via the MAP sensor?

Sixto
87 300D

Yep - the newer models sense the boost pressure electronically, and if the computer thinks it's too high, it will kill the vacuum signal and open the wastegate. But there's no discrete pressure switch, or valve in the ALDA line. Just a different system.

I have total loss of power and no longer hear the sweet whine of my turbo!

How do you suggest that I start checking....I have replaced all of the vacuum lines except around the airbox.

If I use a mighty vac on the 2 actuators controlling the turbo should they hold vacuum?

Any info is appreciated....

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Wayne Jockers
1992 300D

Dont waste time/dollars on that system! Follow this thread from the beginning and save yourself alot of time,future trouble and dollars. Don

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Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles

Hey guys. Just wanted to update you. I successfully converted my 93 300D Turbo back to the pressure type wastegate type outlined in the thread.

I removed the turbo completely to do this. This was not a bad DIY. Some bolts were hard to get to, and you will get some torn up knuckles, but all in all a very do-able project.

FYI: I completely removed vacuum going to the passenger side transducers, etc. I used the F connector at the vac. pump.

Some things I noticed when I got it back together and went for a drive:

1. Transmission shifts smoother and no longer clunks while upshifting (letting off gas)

2. Notable less turbo lag.

3. No more surging- car used to surge when floored, it would overboost to about 20PSI until it stabilized at 14psi...false hope!

4. overall feels more drivable with more linear power curve.

To think, all these benefits, with no more dirty EGR to boot! And a more reliable, bullet proof boost system.

Would HIGHLY recommend this to anyone with this car, with or without a problem with the current EGR wired boost system.

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

To the pressure actuated wastegate. This is on the 1990 300d with 190,000 on the clock. Lucky for me, ATP is only 15mins from my house. A few things i have noticed. Im only getting 11lbs of boost, 12 max. When i hooked up the new actuator, the wastegate was completely closed. I tapped the intake at the test port for the wastegate and the boost gauge. On the highway when i floor it, it doesnt have that much get up. Almost like it bogs down. If i let off the accel a bit, it starts to take off. So its kinda of like it accels when i take my foot off the pedal. I have the egr and flapper disconnneted along with the vac feed off the pump that heads over to that rats nest.

Some background: new injector pump, Clean bango to alda line, little play in the turbo, clean fuel/air filters. Im currently running about b75 in the tank

Anyone have an idea of why im not getting the 14lbs boost like others have mentioned? also, any ideas about the accel issue. The car feels better to drive, but i think it still has more to give....

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VegStew
1983 300SD 70,000 WVO Powered miles
1990 300D In driveway with Head Off - Cracked

edit - Thanks VegStew for pointing out my error

The wastegate should be completely closed when there's no pressure to the actuator.

The actuator should have enough stroke so the wastegate is completely open at the maximum pressure setpoint.

Where is this test port?

I'll wait for the experts to chime in but I'm pretty sure you want the boost signal for the actuator from the compressor outlet for quickest response. The boost gauge should read off the manifold or ALDA line.

Sixto
87 300D

I think you may have this backwards. The wastegate should be closed. As boost builds and it receives the boost signal, the actuator starts to open the wastegate.

Maybe test port is the wrong terminology. The port i used for the actuator is the one to the left of the port with the arrow pointing at it. I would think using the manifold for the boost signal would give the actuator a more true signal on which to open the wastegate.

Attached Thumbnails

 

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VegStew
1983 300SD 70,000 WVO Powered miles
1990 300D In driveway with Head Off - Cracked

You can try to adjust the actuator rod for more preload so it opens later, or a controlled signal leak with a manual boost controller -

http://myautosphere.com/home/modules/smartsection/item.php?itemid=3

The further the signal is from the turbo, the more likely the setup will experience boost spikes. On hard acceleration, it might hit something like 18 or 20 psi before the wastegate can react, if you have it set for 14 psi steady state. You want a quick reacting wastegate but you also want to monitor pressure where it's relevant (in the manifold). Nothing prevents you from physically separating the wastegate signal source from the boost gauge source. The turbo can be putting out 30 psi it can't hurt the engine if the manifold sees 14 psi.

This might not be so easy to do in the car. It's easy to tap the compressor outlet to accept a nipple when the turbo's off the engine. Maybe you can do something with the EGR port in the mixing pipe if EGR's disabled.

Sixto
87 300D

Could the air flap in the air box cause me the acceleration problems? Does anyone that used the port on the intake manifold for the boost signal to the wastegate have the same acceleration issues? Also, what psi are you seeing from that port?

Thanks
Mike

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VegStew
1983 300SD 70,000 WVO Powered miles
1990 300D In driveway with Head Off - Cracked

True dat. I think i need to get the wastegates signal from somewhere closer to the turbo. I cant figure out what else may be causing this accel behavior...
Yar

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VegStew
1983 300SD 70,000 WVO Powered miles
1990 300D In driveway with Head Off - Cracked