I am going to perform this mod for X-mas

This may be normal. The vent line is supposed to always be open, to allow air to be pulled through the vac pump. If you block it, the system would build vacuum and actuate vacuum consumers, like the EGR. Note that the vac wastegate is fully open (zero boost) with no vacuum, and when vacuum is applied it closes (full boost).



I'd swap to the pressure wastegate and remove all that junk. In the meantime, just make sure it's plumbed according to the diagram in the FSM. What is the problem/symptom when driving, btw, with everything connected normally?

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Well. After months of reading about it I've finally completed the wastegate swap. It actually was quite easy; but I did run into a problem.

I had attempted to install from underneath. I had recently left the hospital (major surgery) and after two weeks of laying around I decided to try the swap. No matter what I did I could not access the c-clip that held the old actuator in place. Further, though I did not realize it when I started, I was too weak to do the job.

So I had the bolts off the old actuator but could not remove it. I woke up the next day, completely depleted from my attempt the day before and driving a car without boost. After a few more days rest I drove over to my friends business and we put the car on his lift. I started to work on the car when he said, "Whoa! You're still too weak. I'll have my assistant do this for you."

I thought that was great and went inside while the new actuator was installed. It took much too long but finally the car was off the lift and I was driving home. There was one small problem - NO BOOST.

So I spent the next couple of days building up my strength and wondering how badly I had screwed up my car. Finally, at least a week after I started I went to work on the car again. This time I approached the job from the top. I removed all of the vacuum relay/control-units by the air filter and then removed the inner fire wall.

Once the inner firewall was removed it was very easy to access both the top and bottom mounting bolts and the c-clip. I loosened the nuts holding the actuator. While doing that I observed that the lock-nut that held the adjustable length of the new ATP actuator was loose. I readjusted the set-nut such that the waste gate was fully closed, tightened up the actuator and put a pressure gauge on the intake manifold; peaked at 14 psi.

So the assistant who "helped" with the original install had found it difficult to get the wastegate link to connect to the ATP actuator with the original (correct) setting I had given him so he just loosened the set-nut until it was an easy install. Doing so had caused the wastegate to be permanently opened.

I've not driven much since then; still recovering but I notice that surging and other anomalies that use to appear at certain RPMs and certain load conditions are no longer present. I'm glad to have the EGR disabled and to not have the EDS control anything besides the idle.

As always I acknowledge and thank all helpful and considerate members of this forum. I'd like to specifically thank the following:

GSXR
BOBODACLOWN
AUSPUMPEN

Merry Christmas and Happy New Year to All.

TGD

Sounds like you got er going !!! Didn't happen to find a cheaper source for the actuator did ya? You'd think that was made of gold for the price they want.
I'm still fiddle farting with the rought idle I'm having. 280k miles and compression checks out. It's not the vaccum system, new injectors but now quietly rough, finding air bubbles in the pre-filter and some slight diesel residue on the fuel thermostat housing. Kinda thinking I'm sucking air. Have a bouncing oil pressure gauge that lead me to believe I was experiencing a head gasket failure but the idle smooths out at 1200rpm. I think the system is sucking air or something but running out of places to check. I retorked all the lines but nothing helps.

Congrats on the install !!!

I had the bouncing oil pressure guage at idle for a few months (few thousand miles?) and then the head gasket failed. The gauge would oscillate rapidly, say 2-3x per second. The bouncing gauge was cured with a new head gasket. The gasket failed between the #1 cylinder and the timing chain cavity, and guess what's in between those two? Yep, the main oil passage feeding the cylinder head. Sorry for the bad news, but you're very likely looking at a head gasket job. The good news is, that's not terribly expensive, bad news is, it's a lot of work!

Dr_SJH - glad to hear you got it running with full boost again! Congrats!

part number on unit is as follows 433489-12, but it looks different from the one in the post.

Attached Thumbnails

     

looks like the right one.

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92 300D 2.5L OM602 OBK #59

Well I will install this weekend using the tap from the intake until I drill the housing later.

That's exactly what my actuator looked liked.

The only challenge I had was the clip holding the wastegate/actuator linkage.

I did find taking out the inner firewall very helpful.

I'm running off of the intake manifold and it's working fine.

A number of performance issues have improved including surging and transmission flaring.

The previous owner had the transmission modulator replaced. The vacuum/relay assembly by the EGR/AVR must have leaked as the transmission flared badly. The mechanic who installed the modulator improperly set the VCV and the modulator pressure to compensate. Now that the vacuum system is tight and the rest of the system now properly adjusted the car drives much differently.

Sure glad it's done.

Did you have to modify the shaft, or is this the correct length.

Make the shaft shorter.

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92 300D 2.5L OM602 OBK #59

I did shorten and cut threads but after doing so it appears it was not necessary.

I did not measure the final unit but it sure seems on my '90 w124 that shortening is not necessary.

However, I am not certain and I only spent $8 at Harbor Freight for a Metric Tap and Dye kit.

Shoot, I'm trying to remember. This actuator works in reverse of the vac actuator. Normally open is now closed. Which means boost is always available until it builds up and acts upon the actuator. With the rod length longer it wont actuate until the 14PSI/.95 BAR of pressure builds up ( I believe that is the setting of the special actuator). The adjustment allows you to set a lower amount. Up to 91 specs call .85-.95 BAR (12.3-13.7 PSI) and 92-on .75-.85 BAR (10-12.3 PSI). Not sure what a couple additional PSI will do. But I understand that More Air with out an increase in fuel = higher exhaust temps not more power.

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92 300D 2.5L OM602 OBK #59

When my actuator was first installed the shaft was about 7mm too long. This caused the wastegate to always be open which resulted in no boost.

I think the question is, "can the correct length (I believe it is 107 mm but you should check) be set without shortening and cutting threads. Just take the part out of the box and see if it can be set to 107 mm.

If yes and you do not want to cut the threads go ahead and try. If not cut the threads. It's so easy you can just err on the side of caution and go ahead and shorten it or you can not shorten and then tell us if it works.

That would make sense.

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92 300D 2.5L OM602 OBK #59