How many MLTs leak?

I just did the 10gall Rubbermaid conversion found on these pages. I now know I overtightened. When I searched "over tighten" while adjusting, I only found posts saying their results were tight and unmoving. So, I tightened. Later, when I searched more closely I found lots of posts about not over tightening.

In any case, I'm now afraid to un-do my work for fear I've damaged the rubber insert that comes with the cooler. (My outside washers are actually cutting a bit into the plastic of the cooler - that's how tight it is). Leakage is maybe a teaspoon an hour filled full cold or hot. For now, I'm going to use it and see if it's a problem before I try to fix anything and find it's worse.

I wonder if I'm alone in these results? From searching, it appears most folks were wiser than I and avoided this. But anyone out there working with a little leaking? Or tips on fixing damage from overtightening? (Something I may search out after I try my first batch this week).

Mine leaks the tiniest amount, probably the same. Your teaspoon an hour. I fiddled with it trying lose and tight and after several adjustments and disassemblies (once making the problem worse when I forgot to put a gasket back in.. Fortunately I was just testing with nothing but water that time), I've decided to just live with it. It's probably a bad gasket or maybe an issue with a washer, but I'm not losing enough to be concerned and the mash temp has held just fine.

Yep, nature of the beast, I'm afraid. Most coolers have textured plastic walls and It's really difficult to make a perfect seal against a textured, bumpy surface like that.

Thank you, it's good to not be alone in the world! Can't wait to try it out and see if I can raise my efficiency with better temperature control.

I used this on mine...not a drop of sweet wort lost.

DAP Products - Silicone Sealants - DAP® Household/Aquarium Adhesive Sealant

I think you are using a different cooler than I have, but FWIW, I don't use any bulk head fittings at all. Just a plain old rubber stopper inserted from the inside of the cooler (so that water pressure holds it in place instead of popping it out). Not one drop of leakage in 3 years of use. Simple, cheap and effective. Here's a couple pics of my set-up. Just something to consider.

None of mine do.

Here is one,



Nothing but a fitting snugged tight to the original seal. That idiotic washer some put in there just gives you another place to seal up.

BBL_brewer, what size is that stopper? That's exactly how I want to do mine!!

Butter said:

BBL_brewer, what size is that stopper? That's exactly how I want to do mine!!

Click to expand...

It's a #3. I just took my cooler to the LHBS with me and matched up a stopper to it. I somehow doubt that all cooler drain holes are the same diameter, so you might want to do the same. Or if you have to order them get one a bit smaller and one a bit bigger just in case. Stoppers are cheap.

Mine leaks on occasion bit not very much. The mash temp is maintained and I still hit my numbers fairly consistently. I wouldn't worry about it.

Thanks man!

99% of the bulkheads I see people build have obvious flaws that allow liquid to make it to the threads of the nipple. If you have a metal washer inside right before the gasket, that's the problem.

Mine would be fine for a while then I'd bump it just right and it'd start leaking. I ended up doing similar to the above. DAP all purpose 100% silicone sealant is the trick. It says right on it that it is food safe for continuous food contact and safe up to something like 500F. No leaks since.

I tested my cooler MLT with water, and several o-rings, washers, connectors. All leaked. I ended up with a drilled #3 stopper, a length of 1/4" copper tubing and some hose, and all is well.

Just pour some radiator stop-leak in with the mash. It's designed to work in hot temps. Probably make your brew a little aluminumy-poisoney-shiney..


Actually, do not do that.

Mine hasn't leaked a drop and can go for hours and hours (60qt ice cube). However, when you flip the lids up on coolers with fastened lids, the condensation from the mash can make it look like they're leaking when it's just from the lid.

No leaks. Was having issues until I threw away the gasket that came with the cooler and replaced it with a rubber washer.

No leaks on mine. I used an o-ring on the inside of my cooler to make the seal. The key is to be sure that you're not trying to make a seal on the threads of the nipple. Your seal should be on the smooth, unthreaded portion. My only concern if you're leaking that slowly, is wort seeping into the insulation in the wall of the cooler. That could cause mold/mildew issues.

I thought about the seepage inside issue. But I think, if I remember correctly, at the spot where the seal is there is no access to the insulated part. I seem to recall that the plastic comes together right there and is closed off. I don't want to take mine apart to check and I can't confirm from the pics posted, so I'm hoping I'm correct. Any confirmation on this?

I used an igloo ice cube. It didn't have a valve built in, so I had to drill my own hole. That's why I had to be concerned about seepage. I don't know about the rubbermaid.

I have both a 5 and 10 gallon rubbermaid and neither leak. I have a brother with a machine shop who bent the inside washers to the same radius as the cooler so the fit is flush.