I have SRAM DB5 levers and calipers on my new MTB. The basic problem is that once I have pulled on the brake lever, the calipers do not retract. I figured maybe the pistons were poorly lubricated and followed the process of remove wheel, close calipers, force back open, repeat a few times. No luck at all. Eventually I wondered if maybe the entire system was, so to speak, "overcharged" or maybe had too much pressure in it. I don't know if that's really a thing with a system like this, but I figured it's an easy test... I opened it up, put the wheel on, took a flexible cold pack and wrapped it around the lever for about 15 minutes. After that,, I applied the brakes again... shazam... just about perfect! The problem is that it's really not *that* hot. The bike is in a warm garage-- maybe 85 degrees? I find it odd that the system would have to be, say, 50 degrees to function.

Is there a solution to this? I'd very much prefer to avoid bleeding as I don't have to gear for it and I'm pretty short on money. If there's another way I'd love to know it. Can I justs let out a tiny bit of brake fluid at a time?

Call SRAM for a warranty, if you suspect the brakes are malfunctioning (which, from your description, it sounds like they are).

The pistons retract by the reflex action of the square-edge seal that surrounds the piston. As the fluid pushes on the piston, the seal takes a trapezoidal shape--once the line pressure drops (the lever/master cylinder is reset), the seal reflexes back into a square, pulling the piston back in. Failure of the piston to retract can mean swollen seals, dirty pistons (possible only with use), or uncommonly, manufacturing tolerances being off (the piston being slightly oversized, for example).

Another possibility is an overcharged system (or in the case of DOT hydraulics, one that has taken on a significant amount of atmospheric moisture). A "quick fix" to test this is to face the lever bleed port straight up, open it (and surround it, but don't touch it, with a rag), and spread the pads/pistons manually. Any purge of fluid is significant, indicating a higher-than-normal level in the system. Reinstall the bleed port screw, and clean up any purged fluid using soapy water, and alcohol to remove any remaining residue. If the brake returns to proper function, there are two explanations, as above...a new brake has an overcharged system, or a used one, more than likely, requires bleeding. If the fluid is any color other than golden-straw (the color of SRAM/Avid's fluid), it needs to be replaced. For what it's worth, this would not constitute a malfunctioning brake, but it would answer the question of whether or not they were.

Thank you for the very thorough reply. The brakes are new, as is the bike, so I'll take a shot at relieving the pressure. I'm a little apprehensive-- this is my first set of disk brakes after 24 years of the same bike with rim brakes-- so I appreciate the detail. It seems like the rear brake might need the same, as it has similar problems.

To be clear, do I remove the wheel and depress the lever so that the pads close, or do I simply remove the wheel and, say, turn a flat-head screwdriver when the pads have their normal operating gap?

Yes, you'll need to remove the wheel, and spread the pistons. You can use a screwdriver between the pads, but it can gouge out friction material. There are, of course, commercial solutions which do not have that problem, but there it is.

So not pull the lever while the system is open, unless you want to bleed it...

If you decide to use a screwdriver, use the largest you have, and clean it with degreaser/alcohol before using it.

Thanks for the help. I've attempted this, but unfortunately it didn't help. A very small amount of fluid came out without improving the matter. An LBS said that it sounds like the brakes need to be bled as air in the system is the only thing that would cause this. That doesn't sound right to me. These are, as far as I know, factory-prepped, and it seems unlikely that they would make a mistake like that, nor does it seem like air is the only possible cause, as others are pointed out above. The saga continues.

Hit the lever when the wheel was removed? you thereby created the problem.

I hope not. I followed exactly the procedure in the SRAM service manual, page 29:

I am serious about contacting SRAM. They have a consumer line, though you need to dig a little (not too much) to find the number.

You have done your bit in diagnosing whether or not there is a simple problem, now contact the company so they can support their product. They are quite responsive to such claims, and will often send a replacement, even to a consumer (though you have to send yours back, unlike an account holder, who is usually told to destroy the bad parts)...you can even tell them exactly what you said in your post; a new product, used as directed, should work without issues, and not require further servicing.

Oh... honestly, I figured contacting SRAM would have to happen via a bike shop. I had no idea there was a consumer line. That's very helpful. Thank you.

Well, it's all done. There was a manufacturing defect a while ago that produced a master cylinder piece that was .003mm too large, it turns out, which caused exactly the problem I had. It was fixed under warranty, although I had to pay labor. I don't like that, but that's SRAM's problem, not the shop's.
Thanks for all the excellent advice.