headlight is craking! product?

[Spykem4e]

Hello guys! I have a question:

one of my car's headlight just started to crack slowly. Last year, the crack had about 1 cm long and now maybe 3 cm. The headlight, of course, is made of plastic and I checked on the net for a used one and its about 700-800$ CAN and a new one is about 1263$ at the dealer only because mine was made for HID with headlight washers otherwise it will be approx 150$ for a used one and approx 500$ for a new one.

here's the picture of the headlight:

I wanna know if there's any way to prevent it from cracking more like putting epoxy will stop the crack to go further or I don't know, any idea will be appreciated, tks! Right now, there's is no humidity going inside if the light so thats why I want to prevent.

 

[Boomer]

Try putting some cyanoacrylate liquid into the crack (Super Glue). This is extremely low viscosity and will be drawn into the crak. Let it cure for a few hours at room temp if possible before using. This is similar to those windshield repairs where a very low viscosity polymerizable liquid is injected under pressure. This is the best solution I can think of. By the way, make sure the plastic is CLEAN and DRY before adding the few drops of the cyanoacrylate over the crack. Wiggle the cracked area to ensure the glue gets in there right after application.

 

[hate2work]

Drill a tiny hole at each end of the crack, that will stop it from cracking further. Then seal it with clear 100% silicone.

 

[xpeteyjtx]

Originally Posted By: hate2work

Drill a tiny hole at each end of the crack, that will stop it from cracking further. Then seal it with clear 100% silicone.


Absolutely!
Make sure you don't have moisture in there before sealing it up.

 

[The_Jeff]

The pucker factor is high for drilling plastic, wonder ho one would do it... maybe a high speed dremel with a diamond tip? Agree on the need to relieve stress though.

 

[Spykem4e]

drilling a hole.. you mean drilling through the entire plastic (side to side)?

I could try that next weekend! I'll try to find the 100% clear silicone and a good dremel tip to not break the headlight.

 

[Challenger71]

http://www.autosportcatalog.com/index.cfm?fa=p&pid=332

 

[hate2work]

Originally Posted By: Spykem4e
drilling a hole.. you mean drilling through the entire plastic (side to side)?

I could try that next weekend! I'll try to find the 100% clear silicone and a good dremel tip to not break the headlight.


Yes, just use a regular drill, you don't need a dremel, they turn way to fast to control while drilling. Depending on how wide the crack is, you have to choose an appropriate size drill bit. I'd say for the typical crack that a 1/16th bit would work fine. By drilling a tiny hole at each end of the crack, it eliminates the leading edge of the crack and therefore it stops spreading.

What do you mean by side to side? I'm talking about drilling a hole from the front of the headlight, through the plastic, however thick it is, at each end of the crack. Then seal it.

 

[Dave H]

Super Glue will make the clear plastic it touches cloud over. So if you accidentally make a mistake and get a little too much, it'll look bad.
Relieving the pressure sounds like a good idea. Sucks that your lenses are that expensive.

 

[Spykem4e]

thanks a lot, I'll go to canadian tire and by what I need.

Hate2work, what I meant is that I wasn't sure If I had to drill through the entire plastic or just a bit. I dont know how to explain (looks like my english is saturated lol) anyway, you answered my question

Thanks.

 

[Spykem4e]

Okay, here's the update! I talked about my problem with my girlfriend and guess what? she has the cyanoacrylate liquid (tons of it because they use that at work for esthetic). Before percing the headlight, I just put the cyanoacrylate liquid gently into the crack and we'll see what it will do.

 

[moribundman]

Originally Posted By: Boomer
Try putting some cyanoacrylate liquid into the crack (Super Glue).


It's the amateur dentistry thread all over again. C/A glue isn't very water resistant. When it cures it gasses out and may leave a white film on nearby objects, such as a mirror, which would be really bad. Weld On #4 (www.usplastic.com), an acrylic solvent cement would work for clear acrylics, and Weld On #16 polycarbonate solvent adhesive is suitable for clear Lexan and the like. First the material of the headlight lens needs to be indentified. Then a proper solvent glue must be chosen. Or just stick a wad of Bazooka gum on the crack.