Adaptive Cruise leaking

[Cobra Jet]

Just wanted to clarify a little on this. So, being familiar with this part, just want to state that replacing will likely not “fix” the issue as the new one will do the same thing. Maybe not right away, but eventually. There is a sticky, slimy, jelly glob that gets smashed between the glass and the rain sensor. It’s purpose is to optically bond the rain sensor to the windshield, so it can “see” water droplets. The part is held in with clips, with the gel literally smashed between itself and the glass. Calling it a leak is kinda not accurate. It’s more like the gel kinda seeps some liquid out of itself- it’s already slimy, and that wetness (it’s not much really) will eventually settle enough over time until it forms a drop and drips off and down the glass. It’s not a defect and will not cause a problem, besides the occasional smear on the glass to be cleaned. Eventually it will not do it anymore, but replacing it will start it over again, so to speak.

See, that’s the thing. It’s not really losing anything, besides some surface “wetness”. As long as there’s no air bubbles, it’s good to go. I’m trying to think of something similar to help describe the material, but I’m struggling with that. Manufacturers used to use a physically bonded prism to perform the same function. Those were non removable, but made out of a hard material like plastic or glass. The newer versions are replaceable, but that requires a different method to transmit light between the parts without obstruction (like air bubbles). That method is the transparent gel pad. Here check this out. Maybe it will help describe the gel some. You can see in this video when he tests if it’s cured how it’s kinda slimy, and again when he sticks it to the glass. The surface is slightly moist, and that moisture collects over time into a drop.

Hi Mike,

Thanks for posting that informative tech about the rain sensor gel.

Hopefully your replies will help others who reference back on this and similar threads to help them understand that it's really a non-issue, is a normal characteristic, and as mentioned, replacing it isn't going to "fix" anything that really isn't "broke".

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[Vlad Soare]

See, that’s the thing. It’s not really losing anything, besides some surface “wetness”. As long as there’s no air bubbles, it’s good to go. I’m trying to think of something similar to help describe the material, but I’m struggling with that. Manufacturers used to use a physically bonded prism to perform the same function. Those were non removable, but made out of a hard material like plastic or glass. The newer versions are replaceable, but that requires a different method to transmit light between the parts without obstruction (like air bubbles). That method is the transparent gel pad. Here check this out. Maybe it will help describe the gel some. You can see in this video when he tests if it’s cured how it’s kinda slimy, and again when he sticks it to the glass. The surface is slightly moist, and that moisture collects over time into a drop.

You mean what's dripping onto the windscreen isn't the gel itself, but just moisture? What we call a gel is actually a slime now and won't drip?
Still, if that oily thing, be it moisture or whatever, used to be between the gel and the glass, and now it isn't, then something else (air?) must have taken its place, mustn't it? Won't air pockets appear, which is what the gel was supposed to avoid in the first place?

 

[Mike Pfeifer]

You mean what's dripping onto the windscreen isn't the gel itself, but just moisture? What we call a gel is actually a slime now and won't drip?
Still, if that oily thing, be it moisture or whatever, used to be between the gel and the glass, and now it isn't, then something else (air?) must have taken its place, mustn't it? Won't air pockets appear, which is what the gel was supposed to avoid in the first place?

The moisture isn’t water, not sure if it’s oil or not, but it feels oily to the touch. If you took the rain sensor off and stuck it on a piece of paper and removed it again, it would leave a circle where it was. If the pad was dry, it would never stick at all, so it needs it to do it’s job of sticking. It’s like these things, they also leave behind an oily residue.

Will it eventually dry out? I have no idea, but I think the timeline for that may outlive any car it’s installed in, with the exception of collector cars. The video shows it’s easily replaced if it ever needs it.

 

[ZXMustang]

Bumping this because I've been dealing with the RLS or "rain light sensor" for a while now since I had to have my windshield replaced.

As posted above, its a clear gel pad. When its put on, its floated on with some sort of liquid. Like window tint is installed wet. Then it dries and the water will evaporate out from under it. Or in this case, leak out. As long as the rain sensor circle on the outside is black except for the eye, then you are all good. As said, let it cry out and it will eventually be done. It takes a while because of how thick it is.

Also it has to be there to take up the space between the clipped on sensor and the glass. Its like a cell phone screen, it has to be put on wet and if you fuck it up its garbage. You need to pull it down and start over.

Mine keeps getting a massive bubble under it when the fluid evaporates out. So I get this huge air bubble I cant get out. And I end up needed to pull it down and start over. Man I hate this thing. God help you if you have a 401a car and need a windshield replaced.

 

[bankyf]

Bumping this because I've been dealing with the RLS or "rain light sensor" for a while now since I had to have my windshield replaced.

As posted above, its a clear gel pad. When its put on, its floated on with some sort of liquid. Like window tint is installed wet. Then it dries and the water will evaporate out from under it. Or in this case, leak out. As long as the rain sensor circle on the outside is black except for the eye, then you are all good. As said, let it cry out and it will eventually be done. It takes a while because of how thick it is.

Also it has to be there to take up the space between the clipped on sensor and the glass. Its like a cell phone screen, it has to be put on wet and if you fuck it up its garbage. You need to pull it down and start over.

Mine keeps getting a massive bubble under it when the fluid evaporates out. So I get this huge air bubble I cant get out. And I end up needed to pull it down and start over. Man I hate this thing. God help you if you have a 401a car and need a windshield replaced.

The Ford procedure does not say anything about being put on wet. The procedure more or less says clip it in and plug it in, that's it. It sounds like you are having some other problem possibly related to the new windshield, or perhaps you need a new rain sensor. The one I purchased for my F150 was relatively inexpensive.

 

[RagmopInKona]

This is the part I don't get. If the gel is there for a reason (i.e. to bond the sensor optically to the glass, so that it can see water droplets), then how come losing it is not a problem?
Will it be able to see the water droplets exactly as well without the gel as it does with it?

My guess is like natural peanut butter, as it sits, some of the oils seperate . The gel is still gel, just some of the oils seeped out

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