Although our holding tanks valve is less than 4 years old, it was slowly leaking - both. I tightened the bolts, but to no avail.
Well, the smart thing to do would be to change the seals - 3" about $5.25 and 2" about $4.75 - they even come with replacement bolts. (They should come with replacements, as all 8 bolts were very badly corroded.)
Well, nice warm Sunday, and I have nothing better to do than fool around with my holding tanks. Got the 2" (gray) free with not too much effort.
Got one bolt out of the 3" (black) and other three would not budge. Hot foot it down to local Auto Zone and get magic spray that will loosen anything. After magic spray, got out 2 more, but still left back bolt.
Have an easy solution for that. Put vice grips on bolt head and socket on nut, and just break or shear the bolt with brute force (remember, they are very inexpensive zinc plated bolts.) Time and time again, no such luck.
Well, don't jump ahead in reading - will spoil the story. Sure I have a Dremmel tool with a very good cut-off wheel that will cut anything. Attack the stubborn bolt, and with a little smoke (which vaguely smelled like burning poly styrene) popped the the head off, and successfully pulled bolt, and got the valve apart. Oh no, you read ahead -
the smell of burning plastic was of course the bottom valve half and the corner of the slide portion of the valve. Now, of to local supply house to get new valve. About $60, time to drive to RV supply, and to date almost 5 hours of aggravation.
If your bolts look 1/2 way serviceable, I would IMMEDIATELY go to Lowes, and buy all stainless and replace them, or late in the live of your Moho, you'll be replacing more than just the seals in your valve(s)! Live & learn.
New valve goes in this evening, and as a little extra bit of insurance, I'm going to use a lot of special waterproof silicone grease.