Even though the old sealant may still be sticky, I think it would be very wrong to not clean it out and install new sealant. The old sealant has been compressed by the old windshield and there would likely be voids if you tried to get away without replacing it. Look at section 64 in the shop manuals. It has pretty thorough instructions on windshield replacement. Also, Dan Brindle has a good BTDT section on his website.
http://www.kondratyev.com/porsche/windshield.htm
I watched the pro do my windshield. As I recall he used a utility knife blade around the edge of the windshield to separate it. Maybe it looked easier than it was to do, but he got the cracked glass out in one piece in a few minutes. It took a fair amount of strength to pull the blade around the glass. Then he removed all the old sealant. I remember it not looking too fresh in my 89. He thoroughly cleaned the channel -- not sure what solvent, but it was all gone when he finished. Expect a fair amount of dirt and debris to clean out. also, don't overlook the rubber spacer blocks. The installer primed it -- it may or may not have been paint, but he said the primer was important to seal the surface. After that he used a caulking gun to dispense the new sealant, as Tommy mentioned. That part was actually pretty impressive as he doled out a long rope of even dimension and strung it around the channel.
Dan mentions that 3M makes a sealant kit. Porsche does as well (look at shop manual for part number). My installer came with the Porsche kit as ordered by his company. He looked at it briefly and said he would not use it and credit me for it. Who knows, it may have worked just as well, and I imagine that or the 3M kit is what you will have to use.
Bill Ball
89 S4
====================
Of course, there are deluxe ways to do the job.
http://www.hswtools.com/detail.asp?AST-windk
Wally
====================
Even though the old sealant may still be sticky, I think it would be very wrong to not clean it out and install new sealant. The old sealant has
been compressed by the old windshield and there would likely be voids if you tried to get away without replacing it. Look at section 64 in the
shop manuals. It has pretty thorough instructions on windshield replacement. Also, Dan Brindle has a good BTDT section on his website.
http://www.kondratyev.com/porsche/windshield.htm
I watched the pro do my windshield. As I recall he used a utility knife blade around the edge of the windshield to separate it. Maybe it looked easier than it was to do, but he got the cracked glass out in one piece in a few minutes. It took a fair amount of strength to pull the blade around the glass. Then he removed all the old sealant. I remember it not looking too fresh in my 89. He thoroughly cleaned the channel -- not sure what solvent, but it was all gone when he finished. Expect a fair amount of dirt and debris to clean out. also, don't overlook the rubber spacer blocks. The installer primed it -- it may or may not have been paint, but he said the primer was important to seal the surface. After that he used 3M has a windshield adhesive that does cure and it is not petroleum but
Urethane based. This is what was recommended to me when I replaced my hatch
glass. Also, I tried every known solvent on the window glass when I was
prepping for paint. It turned out that good old paint thinner was the only
thing that touched it. When using the Urethane stuff you have to be very
careful of prep and also there are primers for different types of glass much
like the primer you use for reapplying the mirror button. If you don't use
the primer you will get leaks like I did because as it cures it shrinks and
pulls off the glass.
Jay Kempf
79 US 5ish speed
========================