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Confused: should I use Sikaflex urethane or silicone caulk as per manual


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No leaks that I know of from my windshield in my new to me Safari Simba 07, however, I would like to scrap off whatever is there and reseal around the top of the windshield. The manual says use black silicone sealant for small areas or imperfections around the windshield and black urethane for windshield installation. Not sure which to use and how to remove whatever is there. Appreciate your wisdom, TIA!

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the right tool looks like a scoop that is sharp that you insert into the urethane and pull to cut out the chunk of Urethane. 

https://www.gtglass.com/products/razorscraper-anti-scratch-winged-windshield-urethane-scraper-blade

Then you clean with Prepsol.  Then a primer specific to the new urethane.  Then cut the nozzle on the urethane so it provides a smooth caulk joint (unlike whoever hacked yours) and put a smooth bead.  Then, use a gloved finger and tool / smooth the urethane into the joint and make it cosmetic.

Edited by DavidL
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2 hours ago, DavidL said:

the right tool looks like a scoop that is sharp that you insert into the urethane and pull to cut out the chunk of Urethane. 

https://www.gtglass.com/products/razorscraper-anti-scratch-winged-windshield-urethane-scraper-blade

Then you clean with Prepsol.  Then a primer specific to the new urethane.  Then cut the nozzle on the urethane so it provides a smooth caulk joint (unlike whoever hacked yours) and put a smooth bead.  Then, use a gloved finger and tool / smooth the urethane into the joint and make it cosmetic.

Agree with all the above, gloves and old clothes, I strongly recommend a good caulk gun such as , 

Red Devil 3989 9" Extreme Duty Caulk Gun - Thrust Ratio 26:1,Black

as the urethane is quite thick, and put the tube in the sun to warm up if possible.  
 

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I agree with DavidL, the only thing to add is to have mineral sprits on hand, a lot of rags, and rolls of blue tape.  Having done this kind of work many times, put the blue tape on at the point where you don't want the urethane to get on your paint (it wants to go everywhere), carefully apply the caulking as if there was no blue tape there, tool with mineral spirits on your hand/glove.  When all the caulk is installed immediately remove the blue tape and clean any excess with rags soaked with mineral spirits.  I have found that this method creates a nice clean line that looks like the windshield gasket just extends onto the paint surface and stops any potential or current leaks.  This method also works for belt line seal & slide out panel caulking failures.

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The 2009 Camelot’s used BOSTIK #1100. The 3M cross reference is 3M #540. I would replace with a similar Urethane based product. Never use a Silicone caulk on an RV.  The UV will destroy it.

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Tom,

Would I need a primer with the 3M #540? A friend recommended  the following because you don't need to prime:

Sealant Windshield Urethane Glue Sikaflex P2G Primerless Adhesive

Thank you!

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1 hour ago, martinsimba said:

Tom,

Would I need a primer with the 3M #540? A friend recommended  the following because you don't need to prime:

Sealant Windshield Urethane Glue Sikaflex P2G Primerless Adhesive

Thank you!

https://multimedia.3m.com/mws/media/569029O/3m-500-series-polyurethane-sealant-data-sheet.pdf

If you get the metal and the original rubber cleaned properly, then no.  I don't have any information or experience with the Sikaflex materials. My manual had a specific callout for the material and I cross referenced it.  

As to cleaning, I'd go easy and get all the old caulk off using mineral spirits and scraping.  I have successfully used WD-40 to soften up adhesives in the past. My usual procedure is to soften the adhesive and scrap it off.  Then I wash the surfaces with a mild detergent mix of Dawn dishwashing soap and water and rinse. Then, I "activate" the surfaces with acetone.  Some GASP at this. It is a matter of being careful. I use a cotton rag with the acetone applied to it and wipe off the excess material. At that point, any of the left over adhesive will be sort of "gummy" and not really an issue. BUT, I do get all of the adhesive off and down to bare metal or bare rubber.

Then apply the new sealer and go from there.

 

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Now I am dazed and confused,LOL.

After scraping off the black substance fairly easily, it is paint underneath and I am not sure it is urethane there above the gasket where I am working. The window appears to be "Floating" in the gasket.  As per the manual, there are 3 choices highlighted that are recommended,  silicone, urethane  and acrylic-please see the manual picture and I appreciate any thoughts.  

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The unsightly black mass on the lip of your gasket is most likely someone's failed attempt to seal a loose leaky gasket. When I had my windshield replaced, Coach Glass sent me tubes of black Bostik 70-08A Windshield Adhesive. The installers only used a tiny bit of one tube to seal where the gasket seemed loose from the body opening. None on the glass itself. Not over the lip like in your picture but he lifted the gasket lip and ran it between the rubber and body. None of the sealant is visible after cleanup. BTW, I would think that there should also be a gutter strip over the top and partial sides tightly sealed to the windshield gasket. I can't find a link for the one I have right now but surely someone would know a source. And I don't use silicon anywhere except maybe around the bathroom counter top.

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I would not use Sykaflex on anything unless you want it there forever. We use it in our sand plant to glue rubber in place and once it sets it will not let go. Extremely hard to clean up. 

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44 minutes ago, SteveD said:

I would not use Sykaflex on anything unless you want it there forever. We use it in our sand plant to glue rubber in place and once it sets it will not let go. Extremely hard to clean up. 

I used black Sikaflex (can't recall the number) around my passenger side window.

Super nice product to install, with plenty of time before the skin hardens!

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