mash tun won't seal

[Metsbrew]

i'm upgrading to a 150 quart igloo cooler for double/triple batches. But no matter what I do, it won't seal. Anyone have any suggestions. My 50 quart cooler I had no trouble with.

 

[Hoppylikerabbits]

Are you not sealing where the valve is? Try putting on a few extra Washers and shim it up to pull everything together tighter. If not try putting a food grade seal on the inside and the outside. That should work.