non-obvious vacuum leak

[Peter Lucas <lucas@xxxx>]

A few months ago I replaced my water pump (an *excellent* way to get 
to know your engine compartment, BTW). Before this procedure, my 
engine ran flawlessly. Afterwards, I found myself a disappointed 
member of the Slightly-Rough-Idle-When-Cold Club. Naturally I 
started looking for a loose wire or a vacuum leak. I looked 
*everywhere*. Couldn't find a thing. I was just about to throw in 
the towel and take my manifold off again to check those deep 
connections until...

Last night, for unrelated reasons, I happened to be underneath my D. 
As I lay there enjoying the view, I happened to glance at the front 
of the automatic transmission. "What", I wondered, "is that funny 
bent tube sticking out of the front of my transmission?" Then I 
noticed the vacuum hose dangling right below it. In a flash of 
insight I put two and two together. Then I put tube and hose 
together. My engine has been purring happily ever since.

The front of the transmission would have been the *last* place I 
would have looked for a vacuum leak resulting from a water pump swap, 
but evidently I disturbed the line leading from the engine to the 
transmission fluid pressure modulator (which is what, as it turns 
out, we are talking about) enough to break the connection.

So, there's another item to add to the "where to look for air leaks" checklist.

--Pete Lucas
VIN #06703