Adjusting the wastegate on the KKK turbo - PeachParts Mercedes-Benz Forum

Thomaspin · #1 04-28-2003, 01:59 PM

My 1983 300SD uses the KKK turbo. Per the book, they started shipping the KKK (in addition to the Garret) in 1/1983 and mine is a late 1983 car.

I checked the boost at the line between the changeover switch and the ALDA and I'm getting 10 psi.

I would like to turn this up to 14 psi (just shy of 1 bar) and remain within factory spec. (<1.1 bar).

The adjuster on the KKK is on the right hand side of the turbo (from the driver's seat) and is very close to the frame. It uses a 10mm lock nut - I can get a 1/4" drive socket in there to loosen the nut but then I have insufficient room for my ratchet. Any ideas how I can get in there? I assume you turn the adjuster in to get more boost?

Also, what is the corresponding adjustment on the ALDA to enrichen fuel flow?

I have searched the archives and they seem to focus on the Garrret turbo.

Thanks in advance for any help.

gsxr · #2 04-28-2003, 03:34 PM

The 10mm nut is a locknut. You loosen this, then adjust the center shaft with an Allen (hex) wrench. Screw it in (CW) to increase boost. Try a half to one turn at a time, them re-test boost pressure. 14psi is a good target. Don't expect a big power gain, my car had zero power gain from 10 to 15 psi. Adjusting the ALDA may not work, as the real fuel limit may be the full-load fuel setting internal to the IP (rack stop setscrew). That requires pulling the IP out to adjust - not fun.

Good luck,

Thomaspin · #3 04-28-2003, 04:10 PM

...but my problem is I cannot get at the lock nut as it's so tight to the chassis channel. Do I have to remove the turbo to do this?

gsxr · #4 04-28-2003, 04:19 PM

Ewwww. On my 603 engine there's no clearance problems. Try an offset box wrench, otherwise you may need to remove the turbo; or unbolt the engine mounts & raise the engine enough to access it (not sure if that's possible). Or if the socket will go on, use Vise-Grips to turn it instead of a ratchet. I didn't think it was that tight in there!

Thomaspin · #5 04-28-2003, 05:04 PM

I did try an offset wrench - won't reach, but raising the engine is a neat idea, especially as I have to replace the engine mounts anyway. The vice grips may work - I would never think of that - I'm just too nice to my tools!

Any idea how many turns add 0.1 Bar? Don't want to do this too often!

BTW, what's the secret to keeping the 603 explosion proof? I like the idea of a 300/350SD(L) but they seem to have a poor rep for head gasket leaks or bent con rods, respectively.

gsxr · #6 04-28-2003, 05:56 PM

KKK turns: On my car, the first 1-1.5 turns did nothing, then the next 1/2 turn was like an extra 2psi, went way up after that. Which will be a real problem for you since it's so hard to access the adjustment! I fiddled with mine about 4-5 times before I got it where I wanted.

603.96x (3.0L): These have weak original heads. Have a new head put on, the engine lasts about forever. The casting number is cast into the head, above #2 and #3 injectors. Something like 603-016-xx-20, or whatever - only the 7th and 8th digits matter. If "xx" is 15 or less, it is the bad/weak head. If "xx" is 17 or above (used from 1990-up on 3.5L engines), that's the good head. Newest version is 22. Theory is that the trap oxidizer caused a lot of the problem, combined with low tolerance for overheating (115C+). remove the trap, keep temps down, and even the old head may last a long time. Test a car before buying to make sure it doesn't have the first symptom - high pressure in the cooling system when stone cold.

603.97x (3.5L): These have great heads, but weak/flawed connecting rods. Either buy a car that has already had the new rods (or new engine); or buy one that has zero oil consumption & immediately replace the connecting rods (~$1500 in parts, lots of labor). With new rods and a good head, this engine will also last a long time.

The cars that have these OM603 engines are soooo much nicer than the older 617's, that most of us who own them feel it is well worth the possibility of spending a few thousand dollars to fix them should something really bad happen. Thankfully, the cost of rebuild 603 engines from Mercedes has dropped drastically in the last few years, from $9-$12k down to the $6k area, so I'm told.

Regards,

Rick Miley · #7 04-28-2003, 06:24 PM

If you can get a socket on it but not a wrench, how about an adapter to let you turn the socket with a wrench? If you don't know what I'm talking about go to www.sears.com and search for "socket cap set." I would provide a direct link, but their site won't let me.

Thomaspin · #8 04-28-2003, 06:28 PM

Thanks, Rick - guess where I'm going tonight.

Thomas.

TX76513 · #9 04-29-2003, 09:32 AM

If "xx" is 15 or less, it is the bad/weak head.
------------------------------------------------------------
That made my day. 14

mach0415 · #10 12-01-2010, 06:36 AM

To access the 10 mm lock nut, I took a shallow, cheap, 12 pt 3/8 drive 10 mm socket and welded a 3/8 steel 6 inch rod perpendicular to the drive end of the socket. Voila, a KKK waste gate adjustment tool. AND, the allen wrench can go through the socket to the adjustment screw to hold it while tightening the lock nut.