Thought I would provide an update for inquiring minds on the odor issue. Both roof vent caps are in place and not clogged. I took off the toilet bowl cowling (one screw) and tightened the four nuts ¾ to one turn which seemed snug. I assumed the nuts could be over tightened and make a bad situation larger. We are departing tomorrow to go camping so we will get an odor test. With the temperature heating to 85 degrees during the day I am sure the black tank will warm to the occasion. Hopefully this adjustment will solve the problem and eliminate the toilet fragrance.
Our black tank odor did not return after the last four days of camping so it appears that tightening the toilet bowl base nuts closed up the seal between the bowl base and tank and solved the odor problem. Thanks to all for the help.
It may also have been the grey tank that was the offending item and not the black. We had the same issue and I put an RV-360 on the black tank vent as I was convinced that the smell was coming from there. It was pretty rank and definitely more of what you'd expect from black rather than the grey. I was disappointed when the odor remained. A friend suggested one on the grey tank vent too and hey presto the problem was solved.
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Well I am moving on from the exhaust smell to the black tank smell! We dry camped last week and when we cranked up to leave we immediatly noticed a foul black tank odor. We dumped a few miles later and the odor calmed down. As we were only half full I would have thought that I could have traveled if necessary without the gross smell. Lucky for us we were able to dump!
I searched this site for some clues and have downloaded the 2004 36G plumbing diagrams. The sinks and washing machine all go into the gray tank. The toilet is the only contributing device to the black tank. Nothing seems obvious. I have not yet climbed on the roof to see if the vent is blocked. I'll do that Wed.
Otherwise, any clues would be appreciated. Thanks, Steve </div></BLOCKQUOTE>
<span class="ev_code_PURPLE">I just watched RVTV on Wednesday and they talked about this same issue. Apparently it is common to get black tank odors particularly when moving. There are only two ways for air to escape the blank tank...the roof vent and toilet. While you are in motion the air can actually be pushed down the vent tube and has no choice but to come up the toilet. Their suggestion was the RV360 attachment that replaces the standard vent cap on the roof. It is supposed to draw out the fumes. I just ordered one and I will let you know how it works.</span>