She has a little blowby, so I carefully clean air filter housing when changing filter, and look in the intake, and WOW, a ton of nasty black mass is sitting there. Just gobs of it.
How does one clean that without loosening it up and sucking it in the motor?

'80 300CD
non-turbo, but GOES!

Take it off an soak it in a 5 gallon bucket of gas or paint thinner
get some rags and a coat hanger to run thru it.
Roger

When I did my conversion I ran across the same thing. Don't worry, I think a majority of our cars are all the same. I had mine off the car and I took it to my friends garage. He has a parts washer. I bought a refrigerator brush from Lowe's. Long skinny brush with stiff bristles and bendable shaft. I just ran that sucker in and out of there till it all came out. I tried the soaking bit but this was the only way I got it to come out.

__________________
'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

Do not use gas or paint thinner, way to dangerous and they evaporate quickly. I cleaned mine with kerosene much safer and works great. Just soak the manifold in it and get a stiff brush that fits the runners to clean them out.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I know this is gonna sound stupid to you seasoned mechanics out there, but is it a big job to remove the manifold?
Any tips?
Special concerns?

(It seems like on these MBZ's, there are peculirarities that make a simple job on other cars much more complex.
I just replaced my IP shutoff valve successfully, thanks to this awesome forum, the warnings and tips were much appreciated.)

'80 300CD,
non-turbo, but GOES!!!

I think since your a non-turbo it will be much easier for you. The hard part about the turbo is getting everything on in sequence. You should have no problem. Just order a few new gaskets and have at it. It is not a hard job at all.

__________________
'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

If one of the intake bolts doesn't shear off while you're turning it..
ditto the no paint thinner/gas thing, try some biodiesel, it's a great ungunker.

__________________
'84 300SD veg-oil bliss
'83 300SD veg-oil beater

The bolts for the intake are very robust. There are like 6 or 8 and they hold the intake and exhaust manifolds on. Don't worry about breaking them.

__________________
'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

Just a thought... since you suggested bio-diesel for cleaning, why not try cooking oil for cleaning? Might be less smelly....

__________________
Mr Goodfahrt (pronounced FAIRT... means "good trip" in German)

1982 300D Turbo Pastel Gray (off-white) 200k+(?)
newbie but willing

Well, biodiesel is a lot different chemicaly from straight veg oil, in ways that make it dissolve gunk more aggressivly...

__________________
'84 300SD veg-oil bliss
'83 300SD veg-oil beater