The Leer 100XR topper on my 2012 Lariat is letting water in somewhere while not being driven. Water pools up in the bed liner and the carpeted base of the topper is wet on the passenger side.

I originally assumed it was leaking around the side window, but flooding it with a hose did not show a leak. I next thought it was the rear gate window. I glued a rubber 'flap' into position on the rear gate window that had kinda separated from the topper (but was not totally torn off), hoping that would help, but alas, rain leaked in over night.

Any suggestions on how to diagnose this ?

Also, what is the purpose of the rubber drain hose between the topper and the truck ?

 

Instead of flooding the suspected area, use a rain like sprinkling effect. The flooding can cause the water to wash over the leak area. Have someone inside with a light to watch for water. Look for a water trail thru any dusty areas on the inside. If I see a suspected leak, I use painters tape to cover it and recheck....Tha avoids to much tear down for no fix issues. If you do not locate it, try parking on a slope in the next rain. This may help id a smaller area to look into based on how the water runs or puddles inside.

 

I'm not familiar with a drain hose or tube being part of the topper assembly. There is an installation bulb seal that goes between the bed rail and the topper rail. This should be a reasonably soft tube-like seal. Is is possible a previous owner replaced the seal with rubber tubing that isn't sealing?
There really isn't a lot to these toppers. They consist of a single layer of fiberglass (or aluminum), some windows, and a door for the most part. While water is known to follow the path of least resistance, material such as carpet can wick the water upwards against the pull of gravity (at least to a point). If the carpet is wet near the area where the topper seals against the bed rail, that's where I'd be looking for a leak.

 

Here is a link to a slideshow of some pictures:



I have to admit, the topper has been off twice in the past year:

- once to installed a bed liner (they said they replaced the seal)

- once to allow the rear cab window to be repaired (not sure about seal replacement status)


But I was not expecting water running down the side of the topper, which includes a slight overhang over the bed red, to wick its way up into the topper. Especially sitting still ?

 

Re-posting link to pictures:

 

I could be completely misidentifying the source of your leak, but that seal looks wrong to me.
The bulb seal I am familiar with is 'D' shaped, with the flat side being adhered to the bottom rail of the topper. It is also soft like the gasket around your doors.
What I'm seeing looks like a hard rubber tube.

Here's a source: https://www.custompickup.com/shop/in..._detail&p=2700

 

It looks like a hard tube, but its actually soft/rubber.

 

I Googled the Leer topper seals and saw nothing like yours. I wonder if Leer would help you out if not under warranty....might be worth a call.