DIAGNOSIS:
Most common on late 1990, or early 1991 Corvettes and ZR1's.
Rear hatch glass is touching or almost touching the
fiberglass lip near the gas tank flap on one side, but has
about 1/4 inch gap on the other side. Additionally, if the
glass has shifted down too far, the hatch latch striker may
show signs of abrasion, and the plastic trim may be dented
or broken.
PROCEDURES AND CURE:
If you have a really different (intermittent screeching /
creaking / scraping) sound that the dealer cannot identify,
combined with a mis-aligned rear hatch glass, it might just
be a glue adhesive failure. You may find that the sound
travels - seems like it is coming from different areas at
different times. You may take the cabin back interior trim
off and notice nothing loose.
Back in the days of the CAC, good old Jerry Watts knew
what it was immediately. Jerry faxed a copy of the service
alert #93-131-10 about the adhesive failing on the rear
hatch. At first, I could not believe it since the checking
procedure included opening the hatch fully and trying to
notice a wiggling or looseness when pushing up further -
which my glass did not seem to do (I wasn't pushing up hard
enough). But Jerry was right about many other things, so
back to the dealer we went. With the procedure bulletin in
hand, the dealer took my car to the auto glass shop nearby
where they removed the glass hatch, re-glued it, and bolted
it back on - problem solved: $100 bucks, plus whatever the
dealer charged for "diagnostic charge". Yes, the glue
supplier had provided defective glue for a time period, and
it was changed when the GM factory found out about the
failures. I am not aware that one can do this repair at home
since the glass handling is tricky and the hatch is very
heavy and expensive. So, just take the car to a reputable
glass business and instruct them to remove and re-glue the
hatch glass.
The removal procedure, not the re-gluing, is
described in the GM Repair Service Manuals ST-364, section
10-8.
