'91 100q 5 injectors replaced - now car wont start

[John Larson]

On 7/3/2013 7:25 AM, urq wrote:
> As others have noted on your engine there is little to no chance that a leak
> in the intake tract due to injector seals will affect compression inside the
> cylinders.
>
> One fact about all the rest of our kibitzing on this is that we can't see or
> hear what is going on, so there may be some key item of which we are all
> unaware.  There is one principle you should use to guide your investigation.
> The car was running before you had it worked on and it is not afterward.
> The chances are very good that the problem is a result of *something* that
> was done and is not some random, unrelated failure.  Don't focus so much on
> the injector seals ... did the mechanic do anything else at the same time?
> Did they disconnect something during the process and forget to reconnect it?
> Could there have been some sort of accidental damage?  Blown fuse perhaps?
> Mind you, I would be extremely skeptical that this is the result of a blown
> fuse ... just trying to expand the range of possibilities ...
>
> Are you positive that the engine not starting is a result of low
> compression?  Has your mechanic told you what the compression numbers are
> for all cylinders?  Was the compression test done with a fully charged
> battery with the throttle at WFO?  Create a list of what has been checked
> and what you know, so that you don't waste a lot of time exploring theories
> you have already dismissed.  Start with the basics that the engine needs to
> run ...
>
> It seems to me that you are someone who is interested in understanding
> better what is going on under the hood of your car but has not had much
> opportunity to learn.  If that is the case I'd recommend that you get a copy
> of the Bosch Automotive Handbook and read through sections on how an
> gasoline internal combustion engine like yours operates.  As someone else
> noted, it would also be good for you to find a local mentor.
>
> Good luck!
> Steve Buchholz
>
>
Please don't complain that I snipped a whole bunch of stuff out of 
this.  The FIRST thing I would do is set the crank on TDC as indicated 
by the mark on the flywheel.  From there it's easy to look at the mark 
on the harmonic balancer (front pulley).  You should probably be able to 
view the #1 cylinder camshaft lobes when you this because we're dealing 
with an uneven number of cylinders. Might have to remove the valve 
cover, but maybe not.  The two lobes should form a shallow "V".  If the 
flywheel and the front pulley aren't aligned, there's a basic problem 
that needs to be addressed before anything else can be done.  From there 
you need to check the camshaft timing.

John