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Topic: replacing screws on end cap (Read 490 times) previous topic - next topic
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replacing screws on end cap
Hi,
I am replacing screws on end cap with stainless steel, do I first put in a sealant, if so what kind?
Joanne McIntyre

Re: replacing screws on end cap
Reply #1
Welcome to the Forum, we are here to help.

Search my user name for end cap repair, there should be a lot of information.
After prying the loose cap(s) up and cleaning under them wash out the area with solvent, I like Brake Cleaners in a spray can.  I Mask the whole area off and then use 3M 5200 Fast Cure polyurethane, squeezed into the joint.
I pre-drill the screw holes before sealing, making the holes in the caps slightly larger than the screws to limit cracking.
Install the screws while the sealant is still fresh, allowing it to squeeze out. As soon as the sealant is smoothed out, remove the masking tape.
#10  X 1-1/2" stainless steel sheet metal screws work well in this application.
Window and seam sealing | Flickr

Larry

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze

Re: replacing screws on end cap
Reply #2
Welcome to the Forum, we are here to help.

Search my user name for end cap repair, there should be a lot of information.
After prying the loose cap(s) up and cleaning under them wash out the area with solvent, I like Brake Cleaners in a spray can.  I Mask the whole area off and then use 3M 5200 Fast Cure polyurethane, squeezed into the joint.
I pre-drill the screw holes before sealing, making the holes in the caps slightly larger than the screws to limit cracking.
Install the screws while the sealant is still fresh, allowing it to squeeze out. As soon as the sealant is smoothed out, remove the masking tape.
#10  X 1-1/2" stainless steel sheet metal screws work well in this application.
Window and seam sealing | Flickr

Larry

Hey Larry,

Is spraying with brake cleaner sufficient to clean under the end caps? Should the old sealant be scraped away with a putty knife?
1999 MB, 7.3L PowerStroke

Re: replacing screws on end cap
Reply #3
Is spraying with brake cleaner sufficient to clean under the end caps? Should the old sealant be scraped away with a putty knife?

The stuff between the end cap and the body is the failed double-sided tape the Factory used to attach the caps.
I remove as much as possible using utility knives, dental tools, and a 1” putty knife sharpened to a razor edge.
I clean the area where the caps have loosened before starting and then with acetone or spray brake cleaner after the crud has been removed.
Tape the area where you do not want the sealant to remain. 
When applying the sealant, squeeze it into the gap as far as possible, then smooth the sealant with a gloved wet finger before removing the tape.
3M 5200 fast Cure polyurethane has been my go-to adhesive sealant for over 30 years.
Resealing the caps takes a bit of time to do it right.

Larry

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze

Re: replacing screws on end cap
Reply #4
Just a thought…when one removes the end cap to clean and reseal them I wonder if it would be worthwhile to consider applying some kind of marine waterproof treatment to the wood under the end cap?  Having that wood sealed and waterproofed could extend its life by resisting rot in the future.  Another option may be applying minimally expanding foam sealant to the wood area to seal it.

Ron S 
Ron and Linda
Ada Michigan

Re: replacing screws on end cap
Reply #5
Just a thought…when one removes the end cap to clean and reseal them I wonder if it would be worthwhile to consider applying some kind of marine waterproof treatment to the wood under the end cap?  Having that wood sealed and waterproofed could extend its life by resisting rot in the future.  Another option may be applying minimally expanding foam sealant to the wood area to seal it.

That’s not a bad idea, the problem is getting to the wood.
Normally, the end caps have lifted along one or more edges but aren’t loose enough to come off completely, allowing access to the wood beneath. Trying to remove a still attached cap or a section of a cap can result in a destroyed or badly damaged cap. If the cap is still mostly well attached, I prefer to repair the loose sections and leave the rest alone.
Only once did someone show up with a front cap that had completely fallen off.  Caps come loose in areas where the caps are twisted when driving on uneven roads, thermal stresses also contribute to the caps separating.

The factory tried to protect the wood behind the caps and inside of the corner drainage channels by covering the exposed wood with either polyurethane or, used in the older models, asphalt emulsion.  It sort of works for a few years but eventually, the coatings break down and peel off the wood, allowing moisture to enter if there is a leak.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze

 
Re: replacing screws on end cap
Reply #6
FYI, smooth 3M 5200 by wetting your (gloved) finger in mineral spirits. Do NOT use water. Water cures 5200.

Re: replacing screws on end cap
Reply #7
FYI, smooth 3M 5200 by wetting your (gloved) finger in mineral spirits. Do NOT use water. Water cures 5200.

When smoothing freshly applied 5200 Fast Cure. which skims over quickly, if the sealant begins to drag, a wet, gloved finger helps to finish smoothing.
You are right about 5200 being moisture curing, a wet finger does not harm the final product. My opinion is based on 30 years of using 3M’s 5200 in various forms. I have sealed a lot of end caps and windows.

End cap and window sealing.
Window and seam sealing | Flickr

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze