Trouble building a Mash tun

Hello all, I am a big fan of the website and have used it many times when I had problems. This is my first post however, and I am building my own mash tun to try and save some money. I have run into some trouble though because it keeps on leaking on me. I can't seem to get the ball valve, brass nipple, cooler seal, and the female barb adapter to stay tightly sealed.

I used this video to help:


I am using:
3/8" ball valve
3/8" male adapter and 3/8" female adapter
four 5/8" washers (I don't thnk they are fender washers, not really that thick)
5/8" O rings
3/8" - 1 1/2" brass nipple
the seal from my cooler
I have the braided stainless seal supply hose clamped up as well


The cooler keeps leaking from the outside of the hole, like it is not tight in the rubber seal from the cooler. THe ball valve is loose when I touch it, so that is why it leaks, but I have both sides as tight on the threads as possible and it is still not tight. Any suggestions? Is my brass nipple too long, or possibly do I need more washers?

I think it's probably the threaded connections. You need to use teflon tape on any metal to metal threaded connection. Also, when I first assembled mine, it leaked really slow...like a drip a minute. After using it, it didn't drip anymore...I'm not sure if the heat from the mash caused stuff to expand or not.

Make sure it's a tight connection - I believe I used an adjustable wrench to tighten the inside while holding the ball valve part steady with my hand (you don't want to rotate the ball valve because you don't want it potentially being upside down). I tightened it down as much as possible with the wrench.

It's probably a combination of things but yes, it sounds like the nipple is too long. A "short" is mostly likely what you need, if not a 1.5" long one.

Post the exact order of parts that you have assembled and where the cooler wall falls into the list.

Bobby_M said:

It's probably a combination of things but yes, it sounds like the nipple is too long. A "short" is mostly likely what you need, if not a 1.5" long one.

Post the exact order of parts that you have assembled and where the cooler wall falls into the list.

Click to expand...

Thanks for the replies

I have (from outside in) male adapter, ball valve, (3) washers, o-ring, nipple, cooler sealant, washer, female adapter, then SS hose.

That sounds right. I think I used a 1.5" nipple too.

I would teflon tape both sides of the nipple...the one end hooks up to the brass barb with one washer inside:



On the outside, you want the nipple to stick out a decent amount, teflon tape it (it's not in the below pic) and then screw the ball valve into it after you choose the number of washers. You do not have to use 3 washers...you just want the right spacing.



It's great if you have two wrenches - or one wrench and a pair of pliers. You want it to be really tight. Like my inside washer is almost digging into the plastic wall of the cooler.

what do you know...