Black Tank inspection and removal???

[Dean A Van Peursem]

I've posted this question on another thread but didn't get any responses so I'm trying a new thread to see if I can make some progress. The Montana in question here is a late 2006 3400RL which has developed a serious and major leak. This may have been here for some time, maybe since new, since it only leaks when the tank is near full or full. We always empty the tank and put just a couple of gallons in the tank while traveling. We have never dry camped for an extended period of time or had to travel with a near full or full tank to get to a dump station.

However, a few weeks ago I did a more than thorough job of flushing the black tank. I do that by closing the black tank drain valve and run the flushing system until the tank nearly fills up and drain it again a few times. The next morning I had black tank water dripping under the belly pan at the exit hole of the Washer/Dryer sewer pipe. We were going to be gone for the day so I put a 5 gallon bucket under it. By the time we returned the 5 gallon bucket was almost full. But had quit dripping. Upon returning home after tthis trip I pulled the belly pan on the right side of the RV to see if the flushing line was leaking. It wasn't. Only when I filled the black tank nearly full did it start leaking and the leak was huge draining down the side of the tank, in gushes, along side the exit drain pipe of the tank. It's coming from the top or near the top of the tank near there.

But I can't see where or much of anything but running water when viewing from the right side. So I tried to remove some of the belly pan on the left side to get to that area of the Black Tank. First to find out where the tank leak really is and second to try to find the tag on the tank to identify which one I have. But... I haven't figured out how to get the belly pan off enough to get in there. There are too many obstructions in the way such as the propane pipe, drain pipe, etc.

So I'm asking here: What are the steps necessary to get enough of the belly pan off so that I can find out what my tank problem is and if necessary replace the darn thing? Or is this something that a dealer can only do. I'm fairly handy, have the tools and can do this type of stuff but I'm stuck at the moment. I don't want to start removing pipes or dismantling sewer pipes if there is a easier way to do this. So... any help from any Montana owner would be appreciated who has done this or has watched it done would be sincerely appreciated. Worst case I would at least like to see what the problem really is and how big a problem I really have before I take it into a dealer. No, I do not have extended warranty and even with this probably expensive dealer repair I probably will still be ahead.

I just need some help to get past my initial inspection road blocks. I suspect I'll be able to figure it out if I can get to it. Any suggestions or help would be appreciated. Thanks in advance.