I have a slow leak in one tire; every couple of weeks it's down to 18PSI from the desired 30PSI. I'd like to find the leak, but I'd rather not pay $$ for some "professional" soap solution to detect it.
What's a quick-and-dirty DIY solution for detecting slow air leaks? Would I apply it with a sprayer? And, while I'm at it, what kind of bubble production would constitute a "small" leak; a 1/2" bubble per second? a 1/4" bubble per minute?
What's a quick-and-dirty DIY solution for detecting slow air leaks?
If you take the tire off and just visually inspect it prior to putting soap on it, you'll most likely find the culprit (ie: nail, screw, etc).
If you don't find a "smoking gun", mix a solution of a small amount of dish washing liquid into water. Maybe 20-30:1 (water to liquid)? It doesn't take a large amount of the soap for it to create bubbles. Take the offending tire off of the car and liberally spray an area of the tire. Soak one area of the tire, look and watch for bubbles, then move on to the next area. Ensure you do the sides at the bead as well as the valve stem.
Would I apply it with a sprayer?
Yes. I'd prefer a fine mist over a stream, but either should work just fine.
And, while I'm at it, what kind of bubble production would constitute a "small" leak; a 1/2" bubble per second? a 1/4" bubble per minute?
Any noticeable leak is a "big" leak. IOW, any amount of formed bubbles is too much. I'd suggest if your leak is as slow as you're suggesting, there won't be a huge bubble factory going on, so you'll need to pay close attention.
There are 3 methods I would use.
1 - Visual inspection for foreign objects or physical damage
2 - Use a large tub, fill it up with water. Pump up your tire with air. You may want to go above what you would normally use on your car, but be sure to stay below the maximum pressure rating written on the sidewall. Higher pressure usually means a faster leak and makes it easier to find. Place the wheel in the tub of water. You may only be able to get part of the wheel in at a time. This is fine as long as it covers the bead. Watch for bubbles. If the wheel cannot be completely covered, leave ti at one spot for a minute while carefully watching, then rotate and repeat.
3 - For leaks around the bead or fill valve, you can use a bubble solution. Spray it on from a bottle, or brush it on. Home improvement stores sell bubble solutions for leak detection in gas lines.
Method 3 is not as common, but can be good for a DIY if you don't have a large tub you can use.
