possible leak in my WC loop?

Hey guys, I've noticed that over a period of about a month, the small air bubble in my reservoir slowly gets bigger. The coolant isn't leaking anywhere, and I've had this loop set up since April or so of this year. The air bubble is unavoidable as I have dual Danger Den Rad Res's in my setup, both horizontally mounted, and the cap that would normally be on the top of the res is now on the side. That cap has an indentation inside, so there's no way for me to completely eliminate that bubble.

I've already topped it off a few times with more coolant, and experienced the same result. That bubble just slowly grows til I have to put more coolant in.

Anyone have any ideas on possible cause? Is this somewhat normal?

The fact that the res's are mounted horizontally, not vertically, made the air bubble much easier to notice, and it's more of an issue since it can get close to the nozzles when it gets big enough. I've tightened the reservoir caps about as far as they can go.

About how much has it grown? I'm thinking two possible reasons for this. Either there was/is an air pocket in the radiator from when you filled it or you have a very slow leak. If it's slow enough, the liquid might evaporate before you are able to see any affects. Check all of your connections, particularly any where the tubing goes off at an angle from the barb. Feel around the base of the tubing and see if you can feel any dampness. To check for an air pocket in the radiator, if it's there it's most likely in one of the end reservoirs. Try tapping them with something hard and see if any part sounds hollow/empty.

I had a similar issue with my last setup. over the course of a couple months I'd notice the trickling sound in my res getting louder. it never leaked, no discolorations or dampness on any of the fittings. I've heard though that the tubing will naturally seep some coolant through and it'll evaporate, it's just unavoidable unless you use solid tubing (like that one mod with all copper piping) this is one big reason why companies like coolit and corsair have sealed maintenance free systems. They use a special tubing that resists the natural leakage. on a normal setup though, it'll be the norm to top it off occasionally

It's from evaporation. I saw it in both my loops. These systems are not 100% air tight (not much is) so over the course of a few months some of the water in the coolant does evaporate out. Just keep topping it off and all will be fine.

My DD loop looses about 20-30ml every few months.

same, my bitspower loop loses ~ .5mm over 3-4 weeks (looking at my 250mm res) with all compression fittings and double wall tubing.

Thanks guys! :up: I figured I hadn't done anything wrong - i've looked over the loop and it all looks fine. I'll just keep topping it off every now and then.

this is partly the reason why I went with air on my arctic cat project. if it were something I was going to keep I would have tried for wc. but seeing how it's going to get auctioned or raffled, there's no telling who is going to get it. and chances are good that whoever ends up with it won't properly maintain a wc system because they've got no idea that you even need to.

I was actually shooting to get one of the coolit alc systems because it's maintenance free, but they said they're not offering any sponsorships to individuals or companies right now, so that idea went out the window lol