My plan it to go the roto-rooter route. I think that there is also a 90 degree bend at the manifold end as well.
When I had the EGR valve off the engine and I started it, it ran rough. But Given the size of the EGR pipe I was surprised that it ran at all. The pipe is about 1/2" diameter. So my assumption is that there are still some significant blockages in the pipe. The EGR valve has been cleaned out and the short pipe from the exhaust manifold has been cleared out as well. The opening in the EGR valve is quite small as compared to the pipe. Are you sure the engine idle is affected to the degree you said?
Another suggestion was that I run that GM product "top engine cleaner" thru the engine to clear out carbon buildup in the combustion chambers. I used this stuff on my suburban several months ago and it did improve the idle smoothness. But I am not sure what the best way to apply it to the MB V8 would be. I have read that the best way is to get it into the air tubes that feed air into the injector sites. But I would think that the cleaner solution would not be injested equally amongst the cylinders. And I dont think that pouring it down the intake throat would work because then the solution would pool at the bottom of the manifold and would not go uphill in the intake manifold to get into the cylinders. This is not a problem in a chevy 350 because the manifild runs downhill.
Does anybody have any tricks to getting the MB engines to eat this stuff properly? I think that stevebfl has done it but I was not clear as to his application method.
So next step is to roto-root, then top end cleaner, and hopefully not a cat. If I am still failing then I probably dont have any choice about doing the cat.
I got too many cars!! Insurance eats me alive. Dave
78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k