Black Water Tank Problems?

[stardust32166]

I've got a Montana 3500RL. I recently have been having toilet problems. My unit is set up permanently in a campground as a residence. I was getting toilet smell very bad drifting through my trailer. I looked underneath and could see dripping. I pull off the rubber under cover and the insulation and got drenched with black water. I looked all over for leaks but couldn't find any, the black water was pooling in the low areas in the underbelly. I spread cardboard all over the ground underneath so I could see where it was leaking. There were none. The park I'm in doesn't have sewer, so they come around once a week with a maserator and empty my tanks. I haven't used the toilet for a while, so that tank should be reasonably empty, because I haven't used it since they emptied it. I haven't had any smells since then. Tonight I had company and they used the toilet to urinate in. Shortly there after there was a strong toilet odour again. It only lasted about 30 minutes then it went away. I went up top to check the vent but it is not plugged. I'm somewhat at a loss. There have been a few times when the park guys have forgot to drain my tanks and the waste has been visible from the toilet.
Does anybody have any experience with this problem or something similar? I can't see anywhere from the underbelly where it's leaking, I"m at a loss. But I want to get it fixed before winter, I don't want to be trekking out in the snow to go potty at 3am.
Rick

[ctbruce]

Are you running the vent fan at the same time?

Welcome to the forum from Kansas City, MO! Glad you're here!

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[bsmith0404]

Try putting some dyed water down ur tank to see if u can identify where it's leaking. Obviously if you have pooling, u have a leak somewhere. If u still have the bottom removed u should be able to dump 5-10 gallons down with the gate closed. Let it sit awhile and then open the gate. Catch the waste in a bucket, it'll be more than just water I'm sure.

[bobbecky]

You may have a crack in the bottom of the tank, and until it has a large quantity of waste water in it, it may not leak. Our grey tank was leaking, but when empty or had a small amount of water in it, the crack would not leak, but when it finally filled enough, it would leak. You may have to get under it, hopefully after it has been drained and rinsed well and with clean water in it, you may be able to find the leak.