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JB Weld repair observation


Guest crazytrain2

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Guest crazytrain2

Just an FYI on use of JB Weld for repairs from my own recent personal experience.

I had a hard pipe coolant line leak (hole rusted through) on 3.8L which was a &*%$# to get at, let alone try to replace. After several failed repair attempts using JB Weld by itself I made a "JB Weld Band-Aid" by smearing JB Weld on both sides of a piece of paper towel. Wrapped it around the aforementioned pipe and worked like a charm. An additional unexpected benefit was cure time decreased to about 4 hrs (normally 24)

Similarly I had a crack in the plastic (side cap) portion of my radiator - straight JB Weld would split in the same spot when smeared on and over the well cleaned area. I tried the "paper towel band-aid" method and again it worked like a charm.

Just thought I'd pass along, as an FYI - my appologies if wrong forum area - but I know many of you are well versed in repairs, tips etc.

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I used that JB weld to fix a hose clamp for my motorcycle. The thingie part the screw goes threw, it broke off. I was left with a little square of metal with a hole. This clamp is narrow and needed to fit in the rubber channel.I put JB weld on it,and it glued it all together.It looks like a gray hose clamp now.I like the band-aid trick. Thanks for the tip.

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It sounds like the addition of paper towel greatly improves the bond.

I wonder if something like a piece of cotton shirt, nylon, or screenwire would further improve the repair.

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Guest Mc_Reatta

By introducing an aggregate to the JB Weld your moving from an adheasive repair to a composite material repair.

Introduction of an aggregate greatlly enhances the strength.

Suggest you use nylon screening, fiberglass cloth, carbon fiber, or kevlar rather than organic materials like paper towels and cotton rags which will decompose over time and possibly compromise the repair.

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For plastics, I find that the type of plastic you're trying to repair makes all the difference. Some plastics have almost NO adhesion to JB Weld; that's why I really dislike having to resort to using a glue, in lieu of other repair methods (i.e. mechanical).

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Guest crazytrain2

I agree with you whole heartedly about resorting to a mechanical bond whenever possible. However in this case the wall thickness is probably in the neighborhood of .062" ruling out any type of screw fastener I contemplated using some pop rivets but was afraid the plastic would split prior to the rivet "popping"

I also know what you mean about the acheiving adhesion to certain families of plastics, most notably the "olefin" family ie. Polyethelene & polyproprylene. You are doomed to failure with any type of glue adhesion with these types of plastics. You can hot weld, but it is still difficult at best.

In this case the plastic is a filled nylon material (I think) which is not as resistant to adhesives as olefin's are. Prior to the JB Weld I tried patching by hot welding similar material (shaved off of a wire tie) but it would not hold.

When I saw the JB weld cracked in the same spot I knew I at least had good adhesion just needed the "fiber" to achieve greater Flex and tensile strength. And -knock on wood- it has held up now for 3 months or so.

I'm still surprised by the significant decrease in the cure time - that has me stumped but in this case it was a good thing.

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