Replacement windows and gasket leaking

[Julie in Montana]

I need some sage advice again, PLEASE!

I am renovating a 1983 Scamp 13' and had the original front and rear windows replaced recently. I purchased new rubber gaskets from Scamp and had a local windshield repair business cut new Lexan windows (3/16") using the old windows as a pattern, and had him install them. He did not use silicone for the initial installation, and they both leaked.

This week he pulled the windows, applied silicone in the groove and reinstalled the windows into the gasket and put the lock strip back. I know. I know. I explained to him my hesitancy in using silicone. He said he didn't know of any other way to get them to seal, so I caved and agreed.

They still leak. Do any of you have any experience with this? Can you please offer any suggestions on what I try next?

Anyone who has done this job or watched someone do it has to agree it is not for the faint of heart or wrist (in my case), and I feel for him as he's making an honest attempt to get it done right, though it's not an everyday job for him to work on fiberglass.

[Julie in Montana]

I'm just going to move this up the ladder a bit in hopes someone this evening will share some ideas, based on their experience with window replacement ...

[John in Santa Cruz]

is the leak between the gasket and the fiberglass or between the window and the gasket ?

I thought you were supposed to use butyl 'tape' between the gasket and the fiberglass, but I've never done one myself... (its not really a tape, its a black sticky putty that comes in long thin strips on a wax paper backing ribbon)

[mary and bob]

Looking on the Scamp parts store, the plexiglass windows use the rubber weatherstrip with a rubber lock strip that is inserted with a special tool after the window is in place. The plexiglass windows are not the usual flange type with a clamp ring to hold it in, therefore butyl tape won't work. Our Uhaul side windows use the same type weatherstrip to hold them in and they are notorious leakers. It is possible to use some type of caulk in the weatherstrip grooves as a sealer. The problem with the Uhaul window weatherstrip is it is not available with the exact groove width that fits both the window frame and the fiberglass wall thickness, the result being that one groove will be too wide and not fit tight. I don't know those specs for Scamps, so can only speculate that they use an off the shelf weatherstrip that may not fit exactly. Floyd will surely know about those windows, awaiting his comments.

Edit; it is debatable as to if the lock strip goes on the inside or outside, and does it matter. Uhaul put it on the inside so it could be pulled out and that window become the emergency exit.

[Julie in Montana]

Thanks, Bob - and John - for taking the time to offer some ideas!

John - the front window is leaking both from the gasket join at the bottom (which appears tight) and also underneath the ensolite (showing up at the ledger where the seat rests). The rear is leaking at both locations as well, though not quite as profusely.

The installer did not use butyl at the initial installation - though I offered him a new box of the small rope butyl. When I returned it to him last week, he used silicone in the window groove when he pulled the windows out and redid them. I am not sure if he also did silicone in the fiberglass groove, but I can call him and find out. He's really trying to make it seal tight; I think it's just unknown territory.

Bob - the gasket was purchased from Scamp, so it should have fit. The windows are new, but cut using the original windows as a pattern, so I hope they are the same size. Lock strip is installed outside.

Do you think it would help to push some of the butyl rope into the gasket where it meets the window, if I can part the gasket from the window? I fear the only other solution is a big smear of caulking/sealant on the edge of the gasket and onto the nice new windows - clearly not my first go to answer!

[mary and bob]

Julie; I understand that the gasket was purchased from Scamp, but I suspect that they are using a commonly available one, and my point being it may not fit the plexiglass or shell opening exactly. To see a cross section illustration of that weatherstrip go to perfect fit.com and look up AS1456 or As1488. Like I said, Uhaul had leakage problems with similar installations and they address this and a solution in their repair manual. You can find the repair manual in the document section here by clicking on "uhaul" way down at the bottom in the list of camper manufacturers. Look on page #8, starting with comment #7, and again on page 18 comments starting with #5. Their solution seems to be to insert a flexible caulk between the shell and gasket and between the gasket and window frame (plexiglass in your case) I would probably use Proflex sealant that comes in a caulk tube, but that is just my opinion. Uhaul did use clamp ring type windows front and rear and a different type weatherstrip with a fold in lockstep so that doesn't apply to you. Also they use a home made lock strip tool but commercial ones are available for about $15 from Lisle tools. Maybe show Uhaul's solution to your guy for his opinion.

[Julie in Montana]

Thanks, Bob ..

I understand your point now! That might be the case with the gasket not fitting. The fiberglass certainly varies in thickness all over the trailer, so it could easily vary on the walls. The owner at the auto windshield business also mentioned that the gasket I had purchased from Scamp is a common one that he carried in stock. So it makes sense that these are not fitting as snugly as one would hope.

The Uhaul fix you cited makes sense. Sure wish I'd had that information last week before I agreed to his recommendation of filling with his silicone. Going forward from here, it does help to keep that in mind, however.

Sigh ....

(I know part of my frustration is that I can't pop the window in and out to seek a solution on my own and have to rely on a business 30 miles from me to do it.)

[stevebaz]

It is important that the thickness of the gasket channel and the thickness of the Lexan window match. too wide a channel and your going to have problems. window should have been installed with calking around the outside of the gasket and in the channel of the gasket where the Lexan sits. There should been emphasis of really sealing the top half of the gasket where it meets the shell and the bottom channel where the Lexan sits in the rubber gasket at the bottom of the window. Water runs down hill so sealing the top of the gasket well is very important.

This is what we use in our rubber mounted windows in our Bronco's

https://www.amazon.com/C-R-LAURENCE-.../dp/B00QL4T6M2

[mary and bob]

That windshield sealant looks like a good idea Steve. What Broncos would that be, I have the '69 that I bought new.

Edit; finding the right gasket can be difficult as there are limited choices. Ideally I needed one with both grooves 3/16" but none was available and apparently was not when my Uhaul was built as it was 3/16 one side and 1/4" groove the other. Having a joint or seam adds to the difficulty rather than a solid gasket like used in automotive applications.

[stevebaz]

I have one 1974 I've had for 41 years and another 1974 pile of rust awaiting some love some day I have been collecting parts for.

[mary and bob]

Originally Posted by stevebaz

I have one 1974 I've had for 41 years and another 1974 pile of rust awaiting some love some day I have been collecting parts for.

My '69 is still waiting for me to install the new body that I bought in '77. Apologies to Julie for hijacking her thread but hopefully we have been of some help.

[Julie in Montana]

No apologies needed re hijacking the thread, Bob and Steve. You can take this any direction; I'm just appreciative of your help about what to do with my leaking windows, as I am really at a loss which way to go.

The Scamp gasket was sized for a 3/16 plexiglass window, and the Lexan is 3/16, so ... ?? Any consensus about what to do going forward?

[gordon2]

The lockstrip is supposed to be cut a little long and forced in so that where it starts and ends is a tight joint. Scamp also uses a little windshield sealant here. Mine was not cut long and there was a slight gap that leaked. After I added some windshield sealant (only at the gap), it was OK. So there is at least one place where a type of silicone is the right thing to use but it is not needed in the lockstrip if its all sized right.

https://www.youtube.com/watch?v=2NFd6A9lWvI

[Julie in Montana]

Hi, Gordon! And thanks for helping out!

Mine appear to fit relatively tight on both windows, but that being said, I'll get some good windshield sealant and try sealing the join spot. That's an easy place to start round number three on these windows!