Hi all, my 300TDT wont start up. It turns over and the engine wont
catch. I got it going once yesterday and it ran while warm. It was a pig
to start though. What are the likely causes?
1.) switch to ULSD? -if so would an additive help?
2.) fuel system?
3.) other
What are the appropriate diagnostic steps to try here? Any pointers to
get it going?

Check if the glow plugs are working. There's a fuse / fusable link on
the glow plug relay that must be intact for the glow plugs to work.
Replacement links can be bought from dealer and on line.

If the motor runs well otherwise the motor and its fuel system are fine,
starting is dependent only on the glow plugs and the engine's compression.
--
© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

-->> T.G. Lambach <<-- wrote:
I can't seem to locate the glow-plug relay (I thought it was near the
drivers side headlight) any pointers?
Cheers

Black box... with a cover on all the wires... located at the front of the
wheel well.

Tiger wrote:

I think it looks like this one:

http://market.autopartsfair.com/merc..._39579ylh.html

(at least there's a box on my wheel well that looks like it)

Ximinez
--
Our three weapons are fear, surprise, and ruthless efficiency...
and an almost fanatical devotion to the Pope....
http://www.ai.mit.edu/people/paulfitz/spanish/t1.html
http://www.youtube.com/watch?v=gldlyTjXk9A

Tiger wrote:
system somehow keeps developing vapor lock (air bubbles).

Air bubbles.... That's the problem.

Your fuel system has an air leak - at a filter, hose clamp or just a
deteriorated fuel hose. Once air creeps in, usually overnight, starting
is difficult. That's because air can be compressed (fluid cannot be
compressed) so when the injection pump pushes 2,000 psi pressure to the
injectors the air absorbs the pressure and the injectors don't open --
until the air has been expelled from the high pressure lines by your
expensive cranking with the starter.

If you changed a filter check that it's really tight, then check if all
the fuel hose clamps are tight and wipe the fuel hoses with a medium
dark, not black, rag so any leaks or weeping really show up on the dark
rag. You should know the the new ultra low sulfur diesel #2 affects some
old, dried out hoses and sealing "O" rings and so, causes leaks.
--
© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

-->> T.G. Lambach <<-- wrote:
Also I noted that one of the fuel filters has an air bubble in it, I
suppose that this indicates the air ingress is somewhere behind the
filter then. I have not tried to start it today (the weather totally
sucks here).

Prior to starting you can push the air past the injection pump with the
hand primer pump. Pump, pump until all the bubbles pass into the fuel
return line. Incidently, the hand primer pump is also a possible culprit.

Otherwise, flooring the accelerator will shorten the cranking time as
the full throttle fuel flow will expel the bubbles sooner.
--
© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

On Mar 23, 11:44 am, "-->> T.G. Lambach <<--" <"T.G. Lambach at
NoHamorSpamcomcast.net"> wrote:
I have been having the same problem with my 1982 300 TDT. Air appears
in the in-line filter that is before the priming pump. The air
appears to be getting in somewhere between the tank and the engine
compartment. I have replaced all the hoses under the hood and checked
the hoses between the tank and the metal lines from the tank to the
engine compartment, but the air continues to get into the system. It
appears that I am going to have to remove the tank from the vehicle
and replace all the hoses between the tank and the expansion tank.

Does anyone know if bad hoses between the big tank and the expansion
tank would put air into the fuel lines that run between the tank and
the priming pump?