Is JB Weld epoxy overrated or am I using it wrong?

April 25, 2004 10:09 PM

Is JB Weld overrated as hell or am I using it wrong?

I'm trying to re-attach the head of a hollow bolt to the threaded bit, which has sheared off. Having heard countless stories from more mechanically-inclined friends about patching oil pan leaks with this stuff, fixing cracked engine blocks, etc., I figured this had a good chance of working. (The bolt plugs the drain in the oil pan of my 49.5cc scooter.) Two attempts now (with the full 15 hours curing time each) have failed miserably, with the head popping off merely from my attempt to screw it back in place (there is a spring which fits into the hollow section of the bolt which applies pressure as the bolt is tightened). The first time I didn't mix the two compounds sufficiently, only applying one compound to one piece and the other to the other piece and then sticking them together. The second time I mixed thoroughly before applying and had the same result. WTF?

posted by IshmaelGraves to Home & Garden (10 answers total)

Response by poster: I don't expect it to last forever, and I don't know how it will hold up to the heat; but I did expect it to at least screw in without failing. Hopefully I can acquire a replacement but it will take at least a week.
posted by IshmaelGraves at 10:14 PM on April 25, 2004

JB Weld -- as with most A/B epoxies -- is not overrated. The stuff really works. I suspect the residue left from your first botched attempt is what's giving you headaches even after you apply it properly. See if you can sand off any residue, and try again.
posted by majick at 10:25 PM on April 25, 2004

Response by poster: Thanks. I suspect I'll end up waiting for the part, as the shear is pretty ragged and I don't know how much I can sand off. But I have used other two-part epoxies in the past with much better results, so it's good to know that I'm not just going crazy.
posted by IshmaelGraves at 10:29 PM on April 25, 2004

I never really thought JB Weld was heavy-duty enough for something that takes as much torque as a bolt. Good as it is, is it practical to expect this? A crack in an oil pan doesn't have the same kind of force applied to it. How much would a new bolt cost you?
posted by Shane at 8:01 AM on April 26, 2004

JB Weld is great for patching holes but like Shane said holding on a bolt head is a little bit beyond its capability. If you want to give it another try though use a wire brush to clean of the residue of any previous attempts and then start again.
posted by Tenuki at 11:08 AM on April 26, 2004

Response by poster: It'll probably run me all of 5 bucks but it will need to be shipped from Indiana and will cost me quite a bit more than that in missed work, so I was hoping to come up with something that would hold out for a week or so, however, it makes sense that epoxy is not cut out for torque.
posted by IshmaelGraves at 12:25 PM on April 26, 2004

this isn't a bolt that holds anything together, is it? it's just something for blocking up a hole. could you use the epoxy to block the end of the hollow tube (rather than fasten the head on), leave out the spring, and use loctite to keep it in place with it half screwed in? a bit desperate, but...
posted by andrew cooke at 1:39 PM on April 26, 2004

Along the same line...can't you just make a patch out of roofing tin or something, and epoxy that on there?
posted by stupidsexyFlanders at 2:01 PM on April 26, 2004

that's going to make it difficult to fix when the new piece arrives, but maybe it doesn't matter as long as he never drains his oil again...
posted by andrew cooke at 6:37 AM on April 27, 2004

Nah, andrew cooke - a couple of pops with a chisel will get it off. Then all you have are some chunks of hardened epoxy residue, which you can ignore, in a circle around a clean threaded hole, ready for the new plug.
posted by stupidsexyFlanders at 9:45 AM on April 27, 2004