Can the headlight housing be repaired (glued)?

[jonathan909]

I'm finally catching up with our '01 Forester's mashed fender and associated damage (e.g. mirror) from my girls' wisely choosing the ditch over a moose in January.  I'm stuck at the moment on a broken piece of the headlight - the little rectangular spud molded into the grey plastic housing that the signal/marker light snaps into.  I have the broken bit and would like to glue it back on, but I'm well acquainted with the difficulty of gluing many plastics.

I tried methylene chloride (solvent cement) and it wouldn't attack it, and JB Weld's plastic epoxy, which had no bond strength.  Looking at a similar headlight "PC" appears a couple of times where the part number is molded in.  I'm guessing that indicates polycarbonate.  Does anyone know anything that'll work?  I tried to take the coward's way out last week, but couldn't find that headlight (intact) in any of the junkyard carcasses

[brus brother]

Not sure of the compatibility with the material you are looking to bond but I have had pretty remarkable success using crazy (super) glue methods below.

Basically, lightly tag the pieces together and let dry.

I prefer the liquid and not gel formulations.

Then add a layer of fiberglass cloth and once in position,  soak the cloth in more crazy glue. Build up a few layers if you have room.

I used this technique on butt joints with great success.

Also, if you aren't already aware, the addition of baking soda to crazy glue makes a rock hard "plastic". So, after initial tag tacking, if the space is limited, once you wet the surface of the area to be bonded, sprinkle baking soda on the area and wet the area with crazy glue so as to create a callous over the area to be bonded.

There are many videos on youtube that show these techniques.

 

Edited April 21, 2019 by brus brother

[sirtokesalot]

i have had great success gluing the studs back on a side view mirror using gorilla glue. friends kids hit it with a bike and snapped all 3 mounting studs off the mirror. took the studs out gorilla glue and sit studs in place have to clamp whatever u gluing because the gorilla glue will expand. this was 4 years ago. the mirror is till on the door. ive also used gorilla glue to put the mounting tabs back onto a hub cap on my car. it stayed there all winter now.

[heartless]

got this stuff from my local hobby shop - it is meant for building balsa planes, but it has worked great on everything I have tried it on to date, including a styrofoam plane, metal & multiple types of plastics.

fixed a pair of scissors recently with it - the blades were coming loose & moving around due to cracked plastic. they don't move around anymore.

it does not take a lot either. as you can see levels in the bottles.. and I have used this stuff a LOT.  simple 1:1 mix ratio makes it a snap to mix up, and yes, it is pretty much set in 5 minutes

 

[jonathan909]

Update:  Before I had a chance to shop for the "USA Gold Pro" or even get a fresh tube of cyanoacrylate (and thanks for the baking soda hack - never heard that one) a friend laid a tube of LePage Marine Epoxy on me.  I tried a test spot on a spare headlight and the bond seems to be strong, so I'm trying it on the Forester's headlight.  The only downside of this stuff is that it has a long (2 hr) set time, so I had to tape the broken spud in place, as the epoxy wasn't tacky enough to keep it there and it kept falling off (grrr...).  I'll give it a day or two to cure and see how it looks.

Btw, I didn't have to do anything with the mirror - it was smashed so it just got replaced from the boneyard.

[nvu]

i've had good results welding plastic bits back together with a plastic soldering iron.  picked up one at harbor freight, it has a triangle tip and seems to lower heat point than standard soldering irons.  I've fixed door cards, headlight tabs, window switch panels, etc...  it took some time fiddling with techniques until you get to feel on how to melt plastic just enough to weld and not too much that it becomes brittle.

if you get the hfreight kit, the black strips they supply is hot glue and not plastic.  you'll have to get a separate plastic rod welding pack or just use whatever spare plastic bits you have as welding material.  i've found the black abs plastic from old dell lcd monitor covers to be really good for this.

[jonathan909]

Yeah, that's going to work well with thermoplastics (e.g. polystyrene, ABS, etc.), but there are lots of non-thermoplastics (Bakelite, etc.) that won't play nice.  Polycarbonate is a thermoplastic, but I've never tried heat-welding it.  We'll see how the marine epoxy works and take it from there...