Plastic repair, good and bad results

[Kingcreek]

Last year near the end of the lawn mowing season, I opened the hood of my John Deere X320 lawn tractor to check the oil and the hood cracked. About 18” long down the middle of the top.
I finished the season with intentions of fixing it before spring. New hood available from JD for $565.
So I took a chance on a plastic “welder” for $21 from Amazon. Like an electric soldering gun with 2 electrodes that heats these little wire staples red hot. Push them into the underside plastic to kind of stitch the crack together. Snip off the legs and lightly dress with angle grinder. Worked great. Better than expected.
Attempted to fill the crack on top with JB epoxy plasti-weld. Looked great after sanding. When I moved it to touch up with rattlecan it cracked about 1/2 of the length of the original crack.
Tried it again with harbor freight super glue. Seemed to work better. Sanded and cracked again when moved to paint.
Gonna try once more. If it cracks again, F it. Maybe gorilla tape.
Open to suggestions. Thanks

[Nick1911]

Do you know what type of plastic it is?

[Kingcreek]

Do you know what type of plastic it is?

Green. And expensive.
I tried the JB plasti weld because it said it works on all (almost all?) types of plastic.
I suppose I could use the hot clips on the top also, then it wouldn’t flex, but it will look like a zipper.

[zxcvbob]

I think you might need to drill a small hole at the end or *slightly* ahead of the crack to stress-relieve it, otherwise the crack will continue to grow.

[BobR]

I think you might need to drill a small hole at the end or *slightly* ahead of the crack to stress-relieve it, otherwise the crack will continue to grow.

This, stop drill the end of the crack to begin with. Works on aircraft aluminum to keep the crack from growing. It sounds like the "welding worked so I would do that on the expanded crack.

bob

[bedlamite]

If it's ABS, use a soldering iron with filler rod to weld it back together.

[zxcvbob]

I wonder how 3d printer "ABS-Like" resin would work to glue it back?  Put cloth or aluminum tape on the back.  Fill the crack with resin (let it wick inside), then put it in the sun all day to cure.

[Kingcreek]

The crack hasn’t grown and it’s closed good at the terminus. The crack is opening up the edge where it starts.

[JTHunter]

Try some of that "muffler bandage" stuff.  The cheesecloth material reinforces the resin that the netting gets embedded into like fiberglass body filler.

[Kingcreek]

I tried it again with the epoxy plastic weld and it looks pretty good. I also laid on a layer on the bottom side. I think I’ll try putting a couple of the wire staples on the top right at he edge. If it can’t open up there I think the rest might hold.
🤞

[grampster]

Duct tape.

[tokugawa]

" Plast-aid"  two part, powder and liquid. I read about it a M?C mag, for fairing repairs. I have used it and it worked well. Stinks though when it cures. They say it will chemically bond to many plastics, acrylic, abs, etc. Anything the liquid component will make sticky.

 ^Outside of that, a thin piece of steel or alu sheet, some E-6000 and a bunch of pop rivets.

[Bogie]

Does it have to look pretty? Or does it just have to be there?

[Kingcreek]

Does it have to look pretty? Or does it just have to be there?

I was hoping the top would look good while the underside doesn’t matter.
It seems to be holding ok for now. I’ll be painting it tomorrow and then remount the inner shroud that should help stiffen it and support it also.
Since this plastic seems to respond really well to heat and not so well to chemical bonding, if it cracks again I will weld it closed with a soldering iron and green zip ties (I found a perfect match) and then sand and fill as needed.
The initial crack was at the cowl where it meets the instrument panel and traveling forward down the middle of the top. I grab it there at the cowl to tip it forward to check the oil etc.

[Jim147]

Keep us updated. I have one to help a friend fix this spring. That plastic is such brittle crap.

[Kingcreek]

Keep us updated. I have one to help a friend fix this spring. That plastic is such brittle crap.

The electric plastic repair tool and wire clips worked extremely well on the bottom side. I placed them about 3/8-1/2” apart. I used a strap to snug the crack closed as much as I could and hold it that way for the process. When you pull the trigger it gets red hot quick and you just settle it into the plastic then let off the trigger, after a brief cooling pull the gun off the staple legs and leave it embedded. Snip the legs off flush later.
I can send links to the Amazonian source
Plastic Welder, 110V Car Bumper Repair Kit, Hot Stapler Welding Machine with 4 Types Flat/Outside Corner/Inside Corner/Wave Staples Carry Case Plier Cutter, Fender Fairing Welding Systems, Black https://a.co/d/aJoCn7z
 or even loan or sell mine, since I probably won’t ever need it again. I bought an extra bag of clips because I wasn’t sure how many it came with or how many I would need. I have many plenty.
They are commonly used to repair plastic car bumpers and lower front fairings etc.
There are some youtoob videos on the method specifics.

[K Frame]

Need some pixurez of the repair to get a better idea of how it worked.

But yeah, every John Deere lawn tractor I've ever seen that has a few years on it has a cracked hood.