Don wrote:
And of course, the shutdown has worked perfectly this afternoon. Five
drives and five events of "ok, you want the engine to stop, so here
you go."
Question -- could it be [and please no, sweet Jesus, no] that the
vacuum pump is intermittent of failing?
If I threw a vacuum gauge on the output at the brake boost, what
should I read in psi?
I might be worrying needlessly. The shutdown box definitely won't hold
a vacuum.
Don, A hard or cracked piece of hose OR a cracked plastic fitting will
OFTEN leak when cold and stop or leak less when warm/hot. Hook up the
Mity Vac to the cold car and pump it down - and while the vacuum holds,
tug and wiggle every piece of vacuum hose and fitting you can see while
watching the gauge. Vacuum pumps RARELY fail intermittently - although
the check valves can occasionally get debris (or ice in the winter) that
results in vacuum being intermittent. I really doubt that the problem is
the vacuum pump -0 that just isn't what it sounds like, but there's a
small chance it could be that.
Measuring vacuum pressure is NOT usually productive - it requires MUCH
less vacuum than the pump produces to shut the engine down - just a
little suck on a hose connected to the injection pump shutoff should
instantly shut down the engine. If it doesn't (or there is oil in the
tube coming from the shutoff) then the shutoff needs to be replaced. On
123s sometimes the leak is one of the central locking actuators (126s
and later 201/124s have a separate vacuum pump for the central locking).
Is there a difference when the car is locked or not locked? You MIGHT
try disconnecting the entire central locking feed and plugging it's
vacuum supply.
I had a little restrictor about 6" from the vacuum pump crack on one of
my 190Ds and that little monster slowed or prevented the engine from
shutting down when cold for many months - until I finally ran it down.
The biggest problem was finding the proper replacement for the part.
Randy Steele <[EMAIL PROTECTED]> finally obtained a replacement for me.
Marshall
--
Marshall Booth (who doesn't respond to unsigned questions)
"der Dieseling Doktor" [EMAIL PROTECTED]
'87 300TD 181Kmi,'87 190D 2.5 199Kmi, '84 190D 2.2 227Kmi, '85 190D 2.0
159Kmi, '87 190D 2.5 turbo 234kmi
Diesel Technical Advisor MBCA, member GWSection
http://www.dhc.net/~pmhack/mercedes/mbooth1.htm
