The 1990-1993 300D, with the 2.5L OM602.962 engine, has the lovely vacuum-operated wastegate, which is controlled by the computer system (EDS). Due to various reasons, I want to convert this to the good ol' pressure-operated wastegate actuator, like on the older OM602.961 (used in the 1987 190D Turbo). Both cars have the Garrett TB-025 turbocharger.

I have a spare actuator from a T3, but I've been told it won't fit the TB-025... and sure enough, it doesn't (the T3 canister is significantly larger). So... does anyone know where I can obtain a pressure-operated actuator for the TB-025? I emailed a half-dozen suppliers of Garrett parts, and so far none have replied. (Update below.)

Also, if anyone can provide the nameplate data from the older 190D-T turbo used on the 602.961, that would be very helpful.

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Dave
Boise, ID
Check out my website photos, documents, and movies!

You can always get a generic actuator from eBay. Most use the same standard bolt pattern for the head but the shaft length, diameter and thread pitch varies widely.

I found a source that claims to have the necessary parts... they're on order. After they arrive, and I have it all installed on the turbo, I'll post photos, part numbers, and the vendor info in case anyone else wants to do the same thing.

I'll definitely be looking forward to see your results.

Good luck.

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BigBen

'98 E300 Turbodiesel 244 000km
RIP '92 300D 2,5 Turbo 632 859,4km due to engine failure

if you dig up one of my old posts,you will see that with very little modification i used one from an A3 Jetta, had to cut off some of the Jetta mounting bracket and drill a couple of holes in the MB bracket and drill a hole in the pipe between the turbo and crossover to attach the hose to supply manifold pressure to the actuator,really simple conversion and works perfectly. I adjusted it to max out at 15psi on the manifold pressure gauge.Nice to eliminate all the unnecessary vacuum fittings and hose and transducers on the passenger side of the engine compartment. My $.02 Don

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

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

The initial parts sent were not correct... turns out the "universal" bracket doesn't play nice with the offset oil drain tube used on the OM602. And, the actuator rod was offset. After checking with the vendor, and sending him some photos, we discovered that "TB-025" happens to be part of an internal number for them which crosses to a GT unit, which is how we got our wires crossed.

After looking at the photos, and having me measure the rod length, they're going to send out what should be the correct actuator, which should bolt up to the stock bracket. I'm hoping to end up with the same results as Don. I'll keep y'all posted. Photos of the stock turbo are below. For reference, the nameplate data (which is so small even insects would need to use a magnifying glass to read, sheesh) is below as well:


465445-2 (this is the Garrett part #)
003-096-98-99 (this is the Mercedes part #)
WC0148F AT0003 (not sure what these indicate, if anything)

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Brief update: The actuator they sent was about 10mm too long, but I was able to cut it down, and add threads to the shaft to make it work. Also, the nipple on the canister is about half the size of the fitting I put into the compressor housing... I'd prefer matching sizes. So although it appears that it should work fine, the parts I currently have aren't as nice a fit as I'd prefer. I'm going to contact the vendor and see if they have something that's a little more of a bolt-on. The turbo is still off the car so I haven't been able to test drive it yet. I'll post some more pics shortly.

Another update: The swap functions perfectly. Boost is 13-14psi, same as stock, and peaks at 14-15psi during a full-throttle upshift. I emailed more photos to the vendor, asking if they could find an actuator with the proper rod length, they said they will get back to me later in the week - they might be ordering in a part to check out. I'll post more info when I get it. But right now my '93 is running sans EGR and flapper valve, which hopefully will reduce the amount of sooty crap that deposits into the intake tract and cylinder head ports:

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Awesome news! Whenever things get finalized, if you wouldn't mind posting PNs and a contact to your vendor, I would greatly appreciate it! Also, is this something that can be done with the turbo still on the car?

OT, but why'd you have to rebuild the head?

Thanks!

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John Robbins
'05 E320 CDI - 240k
'87 300TD - 318k

John, the wastegate actuator can probably be swapped in the car... but drilling & tapping the compressor housing would be pretty hard. I would recommend removing the turbo if possible. The head gasket blew on this engine, which is why the head (and turbo) came out. While it was off, I replaced the valve stem seals, and cleaned up the ports. Runs much better now, and hopefully the crud won't return now that the EGR has been killed off.

GSXR,

Yes, please let us know your vendor for this sorely needed relief!

Thanks!

You don't need to remove the whole turbo to tap in a fitting, just the compressor housing.

I think a lot of us (myself included!) would prefer not to disassemble the front of the turbo on the car, lol... but yes, that would be an option. Or, using a right-angle drill attachment.

Last night I removed all the vacuum transducers and switchover valves, which are mounted around the airbox. Prior to the wastegate swap, these controlled the vacuum-type wastegate, EGR valve, and air flapper valve (which would divert more exhaust gas into the intake tract, and block fresh air flow). I also replaced the 3-way splitter above the vac pump (1 in, 3 out) to the F-shaped fitting (1 in, 2 out), since there's no longer a need for a vac feed towards the airbox. The engine looks a LOT cleaner with all that junk removed. I'll take some photos and post them here.

The icing on the cake would be to physically remove the EGR and flapper valve mixer housing entirely. This is possible, but the factory solution requires using the Euro-spec turbo, crossover pipe, and cone-shaped connecting pipe. The Euro turbo is basically unobtanium at any reasonable price, so this is mostly just fantasy. The end result would look similar to the Euro 603 shown in the photo below. Another option is to remove the mixer housing and replace it with a section of intercooler hose, like Zeitgeist did on his new 2.5T, which works equally well.

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Here's a photo of the F-shaped vac fitting, and the part number:

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I bet the engine bay looks quite a bit cleaner! Now all you need to do is put an EGT probe where the EGR went, and you can start tweaking the full load.

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John Robbins
'05 E320 CDI - 240k
'87 300TD - 318k