Boosting Situation - Page 2 - PeachParts Mercedes-Benz Forum

jt20 · #16 09-06-2011, 11:16 PM

Quote:

Originally Posted by Aquaticedge

QUESTION NO.2:

How tense should the bowden cable be and where do I adjust it at?

you don't adjust the cable, you adjust the length of a linkage attached to the cable.

There should be almost ZERO tension until the IP rack begins to move.

IE... with the engine running, push on your 'throttle' arm and determine where the RPMs increase. At this point, the cable should only begin to create tension.

To get a feel for where tension is created, pull on the linkage a few times and slowly release tension, you will find a spot where there is sudden decrease in the force required to pull it. That is the spot.

You want the cable to be at that spot when the RPMS increase as you press on the IP lever arm.

jt20 · #17 09-06-2011, 11:22 PM

Quote:

Originally Posted by netboy

On a 617, what is the rubber line from the turbo down to the wastegate? I put a mighty vac on the wastegate side to see if it would hold vac and it will not. My 81 SD will only get 8psi WOT (gauge between mani and alta) with manifold banjo cleaned, over-rev bypassed, and EGR blocked off. The turbo spins freely with no wobble but has some fins chewed up.

I guess there are two leaks, now that you mention it. And that rubber line is the 'wastegate hose'. It send the current boost signal to the wastegate to limit boost.

The wastegate actuator (a rubber diaphragm in a cylindrical housing) is intended to leak.... to a degree.

But the actual wasegate - a valve that lets exhaust gases bypass the turbine once the maximum boost is achieved - should not leak.

And the 603 has a turbo that is noted for wastegate leaks due to carbon buildup.

86-300sdl · #18 09-06-2011, 11:41 PM

May also want to check the condition of the EGR valve, and Up Take Pipe /crossover seals.

My 603 had a leaky EGR. Boost was spilling into the exhaust at that point. I put a plate in where the egr gasket is to stop the leak. Noticed a big difference in turbo response.

There are also several O-Rings (large) sealing the air pathway to the intake manifold from the turbo. Two on either end of the the verticle pipe feeding compressed air from the turbo to the intake manifold. Two additional seals (1 o-ring & one flat gasket for the crossover pipe (over valve cover).

Mine were also leaking.

P.S. I believe the design is to have the boost kick in around 2,000rpm or so. That's when my 603 does. I would also expect the turbo to spin freely though, but it is a lot easier to tighten up these other leak points first.

PPS Re carbon build up- Good point from JT20 above. I had a ton of carbon built up in my egr valve body. Virtually occluded. So I'm guessing too that waste gate carbon build up is another problem area. And a lot of build up in the turbo probably will hamper the turbo spin rate too. I probably should yank mine at some point for a "de-carbon service" job.