It is great to hear another success story. I am also including here my conclusions after doing this modification.... in the event it will be of help.

I just did the wastegate modification to my 92 300D - It was by all accounts a success...as for the boost pressure it appears to be satisfactory ( my all purpose shop vacuum pressure gauge only goes up to 10 on the positive side and it pins it ). I took the control signal for the wastegate actuator off of the intake's unused port ( by adding a fitting ) and it seems to work fine.

! Please note that I did shorten the rod length by the 10 mm suggested earlier in this thread but actually that was not necessary nor helpful unless a person has the 6 x 1.0 metric die that is required to cut additional threads on the shaft. The reason for this conclusion is that before I cut the 10mm off the shaft the adjustable tip was able to bottom out on the threads with the locknut removed and this was also the case after I cut the 10mm off. the end result is this... with the locknut in place which it is necessary there is aproximately 3mm of shorter rod length that is required to achienve the closed and slight pretension load on the wastegate arm ( at rest position of wastegate)... so what I did was I placed one flat washer and one lockwasher on each of the threaded mounting shafts of the actuator and then offered the actuator to the mounting bracket this effectively shortened the rod length the required distance without the need for the die ( the only one that I was missing from my set... isnt it alway like that ). hope this helps someone in there efforts.

Mixer housing removed

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Just an update. I got pressure gauge that goes to 30. The last one I had only went up to 10.
Did some quick checks. My turbo never went above 12.5 psi.
I'm running my charge pressure hose, that controls the wastegate, from the manifold connection that feeds the ALDA that's on the intake manifold. It's a longer run. People were concerned about the distance/time response of the hose. If you're removing the turbo I can see tapping and installing the connector on the turbo. If your not then this way seems to work fine. YMMV.

According to the manual it should be between .85-.95 BAR (12.3-13.7 PSI) at 4000 rpm. I'm maxing out at 12.5 PSI = .86 BAR

I'm good to go. There is no safety system incorporated. Strictly running from the pressure controller and all is well.

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92 300D 2.5L OM602 OBK #59

Just wanted to add to this great thread -- I too finished the wastegate conversion by leaving the turbo on the exhaust manifold and tapping for boost upstream of the turbo housing. I used a mityvac to measure boost and it would easily jump up to 14 psi if I stepped on it. With the pressure line to the new wastegate disconnected, I saw roughly 20-22 psi at the intake manifold. I didn't want to push it much more after that.

There is so much useful info in this thread, and a bunch of it seems a bit interspersed throughout the pages. The info that I was looking for was the sizes of the tap and die for cutting threads on the new wastegate and for the 1/8 NPT elbow fitting that the OP used. As mentioned before, to cut additional threads on the wastegate actuator, you need a M6 by 1.00 pitch die. To tap for the elbow fitting, you need to use a 7/16 - 20 tap (I was a bit nervous so I went to a hardware store to verify). The closest drill bit diameter I found was 3/8". I apologize if this is redundant, but this type of info would have calmed my trepidations about doing a mod like this for the first time!

Driving the car is a pleasure now -- the shifts are crisp and firm, and the car can get out of it's own way (although I did replace some vaccuum lines which helped as well). This mod made me realize that I probably was not making any meaningful boost before, especially since I can clearly hear the turbo spooling now. Part of me is nervous though -- I hope the turbo doesn't conk out on me since it has been on vacation for so long. Luckily, I don't seem to have any major fueling issues either (for now, fingers crossed).

Thanks for all of the useful info and feedback!

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1980 240D
1993 300D 2.5
2002 Golf TDI

Hey GSXR,
I've noticed that there has been no update as to the vendor or correct part number info that you may have found. Do you still have these availible. I'd love to do this job to my 92 300TD OM602. Also, there is one vacuum line to the left of the airbox going into the firewall towards the ventilation system with a prefilter attached to it. Should that connection be re-plummed elsewhere? Thanks for any help you can provide.

BigBore..

please see post # 171 and 181 I had collected the information and placed it in 171 and then there is a note about the length of the rod in 181

Happy Holidays

the vacuum line to the air filter is the vacuum dump, so it vents to atmosphere through that filter.

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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

Chris and pdrayton are correct - thanks guys!

Hey, thanks for the info in note 181. I didn't catch that one. I got fixated on trying to find wether or not the new part# was posted and not seeing it. Thanks for the direction. Love this post !!!

With regards to the filtered vaccum line going through the battery compartment and into the fire wall??? It's definate sounds as if it's going through the ventilation system in some way inside the car. I can hear it hissing as I push air through it (did sound restricted at one point). Where this line ends I have no idea. A little confused why it's tapped into the vaccum draw if it's just ventilating to the atmosphere as that would bleed out the vaccum from everything else like a leak. I'm obviously not understanding something or suffering from the wrong vaccum diagram. Any more detail you can provide would be greatly appreciated.

On my car as I hook up the previous owners disconnected vaccume lines the EGR and Mixer/Cutoff Valve immediately pull full draw and choke off the engine. Connecting the vaccum line going through the firewall as shown in the Vaccum Diagrams bleeds out the system. So either way nothing works right. My guess would be some of the diaphrams or selinoids are bad. My reason for the Manual modifications here.

Electrical: After removing all the vacuum components there's three or four connections to the vaccum selinoids on the left side of the engine bay. I presume disconnecting them will not through any codes or is there something else I should do with them? (1992 Mercedes 0M602 300TD)

Again, thanks for all of your help. Just looking for a little clarity on these items. This sounds like a great mod to do. Especially with all the exterior engine gadgest growing old at 285k miles.

The only function of the computer after this mod is the idle rpm control. The computer can throw computer codes all day will have absolutely no effect on anything. You don't need to wire anything open or such. Just disconnect the vac connectors lines to the EGR and Flapperdohicky (forgot the name). If you want a cleaner install you can remove the switchover valves and such.
REMEMBER to plug off any vacuum lines that goes to the passengers side of the engine compartment. I think there may be a 3-way connector that needs 1 line plugged.

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92 300D 2.5L OM602 OBK #59

Will do. Any particular reason my EGR and flapper would pull full vaccum and shut down the engine? Why is there an open unrestricted vac line into the firewall? When it's connected my egr and flapper do nothing since it's an open line taking the vaccum away. With it plugged Both Egr and Flapper pull full open at idle and at high rev's till the engine dies. I'm just reconnecting after someone diconnected everything. Not sure if the turbo is kicking in or not. Can't hear it spool up anymore and just recently broke my gauges to test it. Seems like the vaccume I'm getting is constant rather than intermitant with engine rpms.

Thanks

Sounds like they've hooked up vac lines incorrectly. It's a vent line. It's just where it goes. Had the same thing.

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92 300D 2.5L OM602 OBK #59

Any other thoughts anyone? I'm planning on tearing back into it this evening. Maybe I'm using the wrong vac diagram and putting things back together incorrectly ? This is the only vac diagram I've found that's even close.(basic version) But it's a dead ringer for what I've got in the system. If you look at the far upper right it shows the filtered (open) line connecting into the rest of the vaccume via a 4 way connection. My system just draws this as an open leak.

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The black tubing is for vent lines to the atmosphere. THe vacuum pump has to suck air into the system, and MB tries to make sure it's clean air by having the vent lines pull from behind the instrument cluster. There may be an inline filter somewhere as well, which keeps dust & dirt from entering the vacuum pump (and therefore the engine, as the air gets sucked into the crankcase).

It does appear you're using the proper vac diagram, but after you delete the emissions junk, you'll have very little vacuum plumbing left. One small line will feed the VCV on the IP for transmission control, the other small line goes to the passenger compartment to operate the climate control air flaps. That's about it though.

Thanks GSXR. That's what I was figuring but something is odd here. The vent line pull air in easily and with it connected both the EGR and Wastegate don't seem to function at all. With the vent line plugged both the EGR and Wastegate pull into full open position at idle and choke the engine out. It seems like the main vaccum line coming from the right side of the engine pulls either a full vaccum or some of the electric selinoids or diaphrams are not working properly. To tell you the truth I'm pretty perplexed at this one. I've never come across this before. Plugging both just removes the turbo I believe so I'm stuck until I can make it manual. I know the vaccum set up is right. I've checked it over three times or so. If the vent line had some resistance it would be possible that the EGR and Wastegate might function as vaccum is increased by RPM's but there is none. Any ideas or testing I can do. Thoughts?

Appreciated.