Noticing the thick layer of black sludge beginning at the EGR port I have removed the crossover duct and the intake mainfold. These I can clean easily but what about the head. I can see the same layer of scum on the head walls and the valve stem.

Is there some way to deal with this or isn't it worht it?

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1991 350 SDL
125,000 miles

I don't worry that much about what is in the head. I clean out the big piece in the EGR and reinstall the tube. This will prevent damage from sucking in carbon.

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Benzmac:
Donnie Drummonds
1991 GMC Syclone
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

One last thing, is there a sequence for tightning the intake manifold bolts? And what torque?

By the way I have cut a thin piece of stainless metal to install between the egr and the intake tube just to be certain.

Thanks for the help.

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1991 350 SDL
125,000 miles