Re: [DMCForum] vaccumm leaks????

["Walter Coe" <Whalt@xxxxxxx>]

> Is there a way for a novice to do a complete vacuum check of the
> engine to make sure there is none???....I thought i read once where
someone
> sprayed wd-40 at various parts of the engine and listened for engine
> improvment but this seems to hit or miss....Is there a better way?

Mike,

It probably wasn't WD-40 that they used.  What people use is starting
fluid
(mostly ether in a spray can).  It evaporates almost immediately and gets
sucked into the vacuum leak where it then burns in the engine as fuel.
When
it burns, it engine runs faster (like it got more fuel) and tells you that
you just found the leak.

I replaced a thermostat on a friend's DeLorean and had to remove the
rams-horns to get at it.  We put "vendor supplied" new paper gaskets that
weren't thick enough (or the gasket surfaces were too warped.)  When we
put
it back together, the resulting vacuum leak vibrated the gasket like the
reed in a wind instrument.  It was LOUD!  We kept wondering, "What the
hell
is making that noise?"  I was really hard to tell were it was coming from.
I sprayed a little oil on there and it quit.  So we made new gaskets out
of
a thicker material.  Problem solved.

Probably the most common vacuum leak that I've seen people living with is
the tamper-proof cap for the fuel mixture adjustment.  Some dummy removes
this plug, messes with the adjustment and never reseals the hole.  This
leaves a significant vacuum leak.  The next most likely leak is a hose
that
got pulled off or rotted off.

When I first got my car, the vacuum line going from the a/c mode switch to
the heater valve was pulled loose.  I could hear it hissing in the
console.
It was a bad enough leak that it affected how the engine ran.

I suggest just poking through all the vacuum lines in the engine
compartment
& compare to the vacuum routing label under the engine cover.  Make sure
they are all going somewhere and are secure.  Some of them are impossible
to
reach without disassembling part of the engine, so don't go pulling at the
ones that go to the rear of the engine.  If one of those is pulled loose,
it
is hard to tell.  You can listen for a hiss, but you have to know what to
listen for.  I tested mine by hooking a hand vacuum pump with a gauge to
look for leaks.  I pulled various hoses loose and drew a vacuum to make
sure
it held.

Walt


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