I bet it’s in the bow or stern, right near the tips. At least that’s where all of Aire/tribs have formed leaks

 

You have to take the bladders out. It's a good opportunity to scrub out the inside, inspect everything, lube the zippers, etc. Repairs on the inside tubes are easy. Replacing them isn't too painful either - and the old, repaired one can be your spare.

 

Fill the tube with air. Fill each valve with soapy water to see if the valve is the leak. For real slow leaks sometimes the protective valve cap will seal it up. If you delve into the bladders you will likely find a previous repair that is leaking. Duct tape, clear tear seal, or some other makeshift patch

 

Randady spot on. Take them out. Clean the insides. Dirty Western rivers leave lots of residue and dirt inside. Inflate bladders and spray with soapy water. Easy repair once you find it. And do the recommended maintenance with the zippers.

 

I would defiantly check the valves before I took the bladders out. I have a mid 1980's Aire Cougar. I had an intermittent slow leak on one of the 4 valves. To find it I took the valve covers off, then added few teaspoons of soapy water to each valve. It took 15 minutes or so to see bubbles, a new O-ring fixed it.

If you do need to pull out the bladders I would start by taking the tubes to a car wash for a good scrub and vacuum. The more dirt and grime you remove the more likely the zippers will work. I would also pick up some zipper lube. My zippers were really gummed up, it took some serious cleaning to get them to slide. Note: if you break or jam a zipper your 'simple patch job' gets a lot more expensive. For patching I recommend the 'Tear-Aid' products, just make sure you get type A or B depending on what your bladders are made of.

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Spray bottle of soapy water. The leak will create bubbles in the soap, showing you where the leak is. Check common leak spots first, like the valves or the bow/stern near the tips as others have suggested.

 

FYI, you probably have thought of this but just incase. To find a leak in the bladder you must remove the bladder so your soapy water mix is in direct contact. Soapy water on the outer tube will not show the leak location since there are many paths for the air to travel between the bladder and the tube.

 

I took 'em out and soaped 'em down three times, still no leak. Cleaned the area inside and out of the outer shell where the valve fits. Put 'em back in filled 'em up to 2 1/2 lbs. No bubbles around the valves. 1 chamber Still going down overnight. Pressured 'em up again and tightened the valve with the wrench until the bubbles quit, and now they are fine. I always check the valves first, but must have missed it this time.

 

I had a ik that the seam leaked real slow and it was really hard to see. If it’s not a pressing issue or it’s just a day boat maybe just run it? Otherwise you gotta find it and repair or replace the bladdder. They are kinda expensive but it’s how it is I guess. I got a 70 dollar Tom kat and had to replace every bladder lol

 

long time airhead here with currently 2 aire rafts, 1 aire cat, and 6 aire kayaks at my house, the oldest one being from 1989. 100% agree first check the valve before removing the aire cell, soapy water test round the outside of the valve and inside of the valve. On old boats it is common for a very slow leak to develop if the valve gets slightly loose, which is easily fixed with the a little tightening with the valve wrench (blow up to full pressure then tighten).