Re: [DML] VIN#04421 Lives Again and Rough Idle - Vacuum Leak

[Warren Wallingford <warren@xxxxxxxxxx>]

I did a long post last year, (I think), on vacuum leaks.  I concur with 
your diagnosis.  An easy and fairly safe method of tracking down air 
leaks is with a spray can of WD-40.  With the engine running, squirt the 
oil on or near the place that might be leaking.  If the idle picks up 
and smoothes out for a second, you've found one.  WD-40 is flammable but 
not as volitile as gasoline.  I've used carb cleaner before, but 
processing that thru the engine sends hydrocloric acid vapor out the 
exhaust.  Usual suspects are: intake manifold, injector seals, w-pipe 
gaskets, and especially the idle tube and associated piping.  You can 
spray WD around pretty liberally without hurting anything, but keep 
enough control to know where you were pointing when the engine note 
changed.  Of course, it will always change if you squirt it down the 
intake, so accuracy and restraint will pay off.
Warren at DMC



Steve wrote:
> Group,
> 
> I am happy to report VIN 04421 lives again after a successful fuel
> accumulator changeout.  During the changeout, one of the fuel hoses
> literally crumbled apart in my hand.  That would have been a safety
> hazard.  The fuel hose was replaced.  
> 
> I also swapped in a new oxygen sensor because 04421 had a rough idle
> problem at start up.  But the rough idle sympton is still there with
> the new sensor.  The old oxygen sensor I swapped out had less than
> 3000 miles on it.
> 
> So after studying section D of the workshop manual, it looks vacuum
> leak is the culprit.  I also have white smoke coming out of exhaust. 
> So the 2000 dollar question is: how do I check
> for vacuum leak?  There is a "propane" method to check for leaks, but
> would prefer a safer method.  Should I put pressure gauge on my
> shopping list?
> 
> Thanks.
> 
> 
> Steve
> 04421




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