Richard Welty's write up:
6/27/2004 (also found in the digests)

[this starts with a narrative of the repair, and includes
with a serious question about something that went wrong during
the task. the question is marked QUESTION so you can skip the
narrative if you find these things boring. i'm also sending this,
separately, to the offtopic list, as i know there are some non-benz
diesel guys hanging out there who may be able to address the
QUESTION]

there don't seem to be too many owners of newer diesel benzes
on the list, so i may be the first to go through this particular
repair experience.

i bought a set of glow plugs for my wife's 96 E300D from rusty
a while back, but never got around to installing them. at some
point i realized they were buried way under the intake manifold,
and in the absence of a shop manual, i was a bit concerned about
the magnitude of the chore. however, after a benz mechanic i know
said it was about 2 hours, i decided it might be worth a shot at
doing it myself.

unusual tools required:

T40 Torx socket (available from home depot, lowes, sears, etc.)

popsicle sticks or tongue depressors (tongue depressors are wider
  and work a little better, ask your doctor for them. my dad was
  a pediatrician, so they were common household implements when i was
  growing up. dad used to use them when labeling his orchids, he'd
  write a description on the depressor and stick it in the pot.)

not quite-as-unusual unusual tools required:

big rubber mallet
6mm allen head socket

conventional tools required:

usual rachet wrench and extensions
10mm socket
12mm deep socket
big pry bar 

step 1 is to remove the tube running from the throttle body
(on the passenger side) to the intake manifold (on the drivers
side.) there's a 6mm allen head bolt on the driver's side, and
a bunch of 10mm bolts for the bracket on the passenger's side.
leave one of the bolts holding the bracket onto the block, and
it'll rotate out of the way. here is where it's good to have
one of those big rubber mallets to knock the tube free; there
are a couple of press fits here. a pry bar may help separating
the tube from the throttle body assembly; it's a fairly snug press
fit (you'll understand after you get the tube out.)  also, don't
break the plastic cover over the injectors while you're removing
the tube (you're more likely to break the cover reinstalling
the tube, but it could happen at either time.) disconnect the
rubber vacuum line going to a nefarious looking device on the
bottom of the tube, and set the tube aside.

remove the plastic cover over the tops of the injectors; there
are 8 6mm allen head bolts here. if you drop one, you'll never
see it again. set the plastic cover aside.

there is an odd assemblage of rubber and plastic tubing running
from another nefarious looking device on top of the head to
each intake port. in theory you could pop the rubber nipples
out of the intake manifold; in practice they are old and brittle
and may tear off. i'll be calling rusty to order replacements
in the morning. probably on an older motor they're completely
plugged up and aren't doing anything right now anyway. more on
that later. you can pull the plastic tubes running to the nefarious
device out at the device itself.

there are two electrical connectors to yet another nefarious
device on the bottom of the manifold, and a vacuum line that
may already have been accidently disconnected during the
life of the car. disconnect these. there is an additional vacuum
line hanging loose; this is the one that you disconnected from
the tube over the top earlier.

there are a lot of torx screws (T40) holding the manifold onto
the head. remove them, and don't drop them. same warning about
never seeing them again applies. if you remove them all, the manifold
will just drop off. if it isn't dropping off, you haven't removed
all of them yet.

the intake manifold should now lift out. the manifold gasket may
well be reusable if you forgot to acquire a replacement before you
started the job. that's another item i'll be ordering from rusty
tomorrow. you could leave the manifold sitting in the engine
compartment (which would allow you to leave the electrical
and vacuum lines in place), but it's much easier to get at the
glow plugs if the manifold is completely removed.

there are a few electrical connections that may need to be
disconnected to devices on the block next to cylinders 5 and
6 for better access, and there's a harness with a fuel line and
some electrical connectors bolted to the carrier for the oil
filter that will be in the way for the glow plug on cylinder 6.
remove the 10mm bolt from the carrier for the oil filter and
move things around as needed.

now we're coming up to the
QUESTION:

in my case, 4 of the glow plugs came out easily (1,2,5, and 6).
two did not. a 12mm deep socket is needed to clear the top of
the glow pug. in my case, the plug in cylinder 3 required much
effort, but i got it done. the plug in cylinder 4 is the problem. the
"nut" section sheared off from the body of the plug, so i have a
small amount of plug sticking out of the block. anyond got any
thoughts on how to get it out? (with 5 new plugs and one dead
one, we're still better off than we were before, with 2 dead plugs,
2 nearly dead plugs, and 2 very tired plugs.)

and for some observations:

1) the glow plug in cylinder 1 was wet with sooty black oil.
anyone know why this might be the case? all of the other plugs
were carboned up, but dry.

2) all the intake runners were pretty sooty. the outermost
ones (cylinders 1 and 6) were dry and sooty. the closer to the
middle you got, the more that they were full of a gooey mixture
of oil and soot. the small ports where the rubber lines from the
nefarious device on top of the head were completely clogged for
the most part. i took some tongue depressors and scraped a lot of
it out, but i wished i had a parts cleaner handy.

finishing is the reverse of disassembly, but watch it when you
put the tube across the top back in. some previous mechanic
wasn't careful, and cracked the plastic cover. i've since replaced
that cover; it's not critical, just a dust and debris cover for
the injector area, but there's no reason why you should crack it
out of carelessness.

richard
-- Richard Welty rwelty@averillpark.net Averill Park Networking 518-573-7592 Java, PHP, PostgreSQL, Unix, Linux, IP Network Engineering, Security