cheburashka
Senior Chief Petty Officer
- Joined
- May 28, 2005
- Messages
- 715
I just finished filling a freeze crack on my GM 3.0 block. The crack was under the manifold, above the freeze plugs. Apparently, that's the usual place. I can offer the following tips:
1) Identify all cracks. Mark where they are located. Draw a picture of the cracks on a piece of paper so you'll have a reference point. It's easy to forget where the actual crack is once you get the JB Weld on top of it, and you may end up patching the wrong spot.
2) If it looks like a crack, patch it. It's hard to tell what is an actual crack, since the water will most likely leak out of the center of the split. On mine there was a faint line that took a U-turn and went back another 1" toward center. I treated it as a crack even though I wasn't sure.
3) Drill the ends of the crack. In my case, I drilled both ends, plus the apex of the u-turn. I also drilled another spot in the same line as the crack but 1/4 inch beyond what looked like a crack to me. JB Weld will fill in those holes just fine and it's better to be sure. Chamfer the edges of the crack into a v shape to make sure the JB Weld has something to stick to.
4) Clean everything down to 10" below the crack. JB Weld runs. If you scoop it up and re-deposit it, you'll end up picking up oil and contaminants and it won't stick. I 'cleaned everything with lacquer thinner and a stainless steel brush, then went over it with brake cleaner and gun cleaning patches to make sure I got all of the oil out of it.
5) Mix the JB Weld thoroughly and let it sit for awhile before applying it. You're putting it on a vertical surface, so you don't want it too runny. I let mine sit for 45 minutes and it was still runny.
6) Take your time. Get comfortable. Unless you're really good at masking off the area to keep the JB Weld contained, you're going to be sitting there for an hour at least with a small spreader, scooping the drips back up on top of the crack. I've seen repairs where almost all of the JB Weld was allowed to run down the block, which looks bad and doesn't help the crack. Keep it in place. After two hours or so it's reasonably firm, so you can go back every 1/2 hour or so to tidy it up. It helps if you start toward the end of the day, so that when the air starts cooling off, the JB Weld will firm up a bit.
7) Assuming you have all of your pressure testing apparatus still set up, apply a bit of suction to the water jacket while the JB Weld is still fluid. I just drew on the coolant hose with my mouth while watching the JB Weld. It just takes a tiny bit of suction. The JB Weld gets sucked back into the holes and the crack and I'm assuming it forms some kind of plug or catch behind the block which should help it stay in place.
8) Cross your fingers. I'm pressure testing mine right now and it doesn't appear to be leaking.
I hope this helps other people who made the same winterizing mistake I did.
1) Identify all cracks. Mark where they are located. Draw a picture of the cracks on a piece of paper so you'll have a reference point. It's easy to forget where the actual crack is once you get the JB Weld on top of it, and you may end up patching the wrong spot.
2) If it looks like a crack, patch it. It's hard to tell what is an actual crack, since the water will most likely leak out of the center of the split. On mine there was a faint line that took a U-turn and went back another 1" toward center. I treated it as a crack even though I wasn't sure.
3) Drill the ends of the crack. In my case, I drilled both ends, plus the apex of the u-turn. I also drilled another spot in the same line as the crack but 1/4 inch beyond what looked like a crack to me. JB Weld will fill in those holes just fine and it's better to be sure. Chamfer the edges of the crack into a v shape to make sure the JB Weld has something to stick to.
4) Clean everything down to 10" below the crack. JB Weld runs. If you scoop it up and re-deposit it, you'll end up picking up oil and contaminants and it won't stick. I 'cleaned everything with lacquer thinner and a stainless steel brush, then went over it with brake cleaner and gun cleaning patches to make sure I got all of the oil out of it.
5) Mix the JB Weld thoroughly and let it sit for awhile before applying it. You're putting it on a vertical surface, so you don't want it too runny. I let mine sit for 45 minutes and it was still runny.
6) Take your time. Get comfortable. Unless you're really good at masking off the area to keep the JB Weld contained, you're going to be sitting there for an hour at least with a small spreader, scooping the drips back up on top of the crack. I've seen repairs where almost all of the JB Weld was allowed to run down the block, which looks bad and doesn't help the crack. Keep it in place. After two hours or so it's reasonably firm, so you can go back every 1/2 hour or so to tidy it up. It helps if you start toward the end of the day, so that when the air starts cooling off, the JB Weld will firm up a bit.
7) Assuming you have all of your pressure testing apparatus still set up, apply a bit of suction to the water jacket while the JB Weld is still fluid. I just drew on the coolant hose with my mouth while watching the JB Weld. It just takes a tiny bit of suction. The JB Weld gets sucked back into the holes and the crack and I'm assuming it forms some kind of plug or catch behind the block which should help it stay in place.
8) Cross your fingers. I'm pressure testing mine right now and it doesn't appear to be leaking.
I hope this helps other people who made the same winterizing mistake I did.