If your old '85 300SD died from overheating the prospects for this car
are NOT good. It's hard to kill the old cast iron 5s and quite EASY to
kill the straight sixes. No kidding.
The aluminum head on this straight six is prone to cracking - when
overheated. So the "soft" spot of these cars is their cooling system. If
you're to have a good ownership experience with this six you MUST take
excellent, not good, but excellent, care of its cooling system,
especially since you're driving it in a very hot area.
What's excellent maintenance? Flush the system and be sure the radiator
is clean inside and out. If there's any doubt, buy a rebuilt radiator
(see: www.resedaradiator.com). Renew the coolant every two years and be
sure the proportion of coolant to water are correct. Finally, when you
drive you need to take into account the car's weakness so when scaling a
long hill turn off the A/C AND moderate your speed - don't charge up the
hill - for the most BTUs the cooling system must shed are upon hard
acceleration, which is usually brief, and long hill climbing, which is
The symptoms of head gasket failure and / or a cracked head are:
overheating, oil in the coolant, coolant in the oil, white smoke upon
start up. That's so you'll know when it happens, then pray it's only the
As to experts on this engine, see: www.mbz.org and join their free
Diesel list, many of those participants own or have owned this engine
and can help you with its technicalities.
Finally, to your initial question. Why is it a slug upon start off but
has lots of power as the speed builds.
As to a baseline, you should know that this car's 0 to 60 performance is
about 13 seconds so have reasonable expectations as to its acceleration.
Accelerator linkage is the first thing to check. Have an assistant
inside the car operate the accelerator while you observe the linkage,
particularly at the injection pump (engine OFF). When the accelerator is
floored the linkage at the IP should come to rest against the full
throttle stop screw. If it doesn't adjust the linkage so it does. This
is a bit complicated; keep a written record of any adjustments made so
you can restore the original setting if necessary. If nothing found to
be amiss with the linkage you need some expert help from the Diesel
group, there are some vacuum controls to the turbo etc. that may not be
operating correctly and that's beyond my knowledge.