Old Pass Thru Hatch Caulking Replacement??

What you are seeing is the putty tape squeezing out at the edges. This is common and does not mean it's failing. While you can remove the door pretty easily, and put new tape in, it's not necessary.

Simply take a plastic scraper blade or maybe even an old credit card, and trim away the excess. Then do what Jayco does, or used to do, which is to run a small bead of polyurethane caulk over the top seam, and then down the sides for a couple of inches. The problem is that the upward facing trim legs catch water and eventually it often gets in, no matter how good the putty tape is.

Here is a video that shows what to use and how to do it. Proflex RV caulk. You'll have to ignore his bad language.
http://www.youtube.com/watch?v=Re19I08pvAQ

It's not hard to pull the frame and reseal. I would suggest the Utube video on doing a window. I've not done the window but I have done two of the doors on our RV.

DD716TED wrote:
Do I have to remove the entire hatch frame to get at all the caulk ...

Yes.

DD716TED wrote:
... What is a good replacement caulk?

Butyl putty tape, that is what the manufacturer uses. It comes in various widths and is available at most RV dealers. It is not expensive. Make sure you put a double thickness in the low spots in the siding.

The butyl may look cracked on the outer edges but it stays flexible and seldom leaks.

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PS that picture is awfully wide, twice the width of my screen. Hard to read the text as I have to scroll sideways to read a line.

Remove all caulk you can get to. Use any caulk without silicone.

Do I have to remove the entire hatch frame to get at all the caulk since it appears to have been put in when the frame was attached, or do I remove only the caulk I can get at??? What is a good replacement caulk?

Remove old caulking, clean area with lacquer thinner or such, re-caulk.

Jim