A mystery Smell

[nebster]

Greetings fellow Newmar-ers,

We've been FT in our 2015 DS since springtime now, and we've recently come up an intermittent, mystery smell. Here's what I know:

1. It started about a month ago.

2. The smell reminds me more of rotting organics, so probably grey tank.

3. For the most part, it only happens when we are driving at highway speeds. It is also very intermittent -- an intense smell, then nothing for hours perhaps, and then maybe it happens again. No more than a few times per drive. But, at least once per drive on the last five or six, 200-mile legs.

4. However, on our most recent leg, we had completely full grey and black tanks (from boondocking) and had no smell. Coincidence? Dunno.

5. When we've encountered the intense smell up in the front, I've sent the enterprising and brave wife back to try to identify where it's coming from. For the most part, we've found no smoking gun. We've very specifically checked the under sink areas (hoping it is one of those vent check-valve air things), but there is no odor there in that enclosed area. We've checked shower -- nothing. We've checked washer-dryer area, nothing.

6. We heavily use all of the sinks, toilet, shower, and W/D -- basically every day. I don't think we have a dry p-trap. And, anyway, wouldn't we have found the culprit at least once per #5?

7. We've never put any special chemicals or treatment in any tank. (We may have to start.)

8. Two times, the smell has been vaguely present or recently flooded the cabin right as I've stopped driving for a break, so I've been able to scurry back myself and try using my own nose. In both of those times, I swear I could smell some of the odor coming in the mid-cabin bathroom (we have only one bath on this bunkhouse model) air-conditioning duct, with the air/circ fan running... basically, the zone 2 ventilation duct. But both times, it has been faint, and I might have been dreaming, or at least wishfully-smelling.

9. In none of these cases have either of the fantastic fans/vents been open on the coach.


My hare-brained theory is that, somehow, we are getting odor at the roof (venturi effect on the vent stack? is that possible?) and then somehow that is getting pumped right back into the mid-cabin via the A/C. Is this even possible?

I'm willing and eager to go replace those simple air valve things under the sinks, but I'm skeptical they are the source. The other things I have read people mentioning don't seem to match up with the observed "facts." I've spoke with Newmar, and the guy was nice, as usual, but could only suggest the under-sink possibility -- which I already knew about from countless discussions you guys have had in previous threads.

Help, mystery!!

[spinn]

Sorry about the issue your having, do you have a clothes washer in your coach?

[rgvtexan]

Washing mach. trap dry. Check your batteries, over charging them, or a bad cell will make them stink.

[nebster]

Originally Posted by spinn

Sorry about the issue your having, do you have a clothes washer in your coach?

Yes, as mentioned. We use this most days, and we've checked that area for the smell each time. No dice. :(

[nebster]

Originally Posted by rgvtexan

Washing mach. trap dry. Check your batteries, over charging them, or a bad cell will make them stink.

Could the trap be dry if we run a load every day? And, if it were easily able to go dry, perhaps because of coach motion while driving let's say, wouldn't we expect to detect the odor in the washing machine cabinet much more than in the bedroom or the front of the coach? I was hoping washer would be the answer, but it doesn't make sense to me (yet).

The batteries are an interesting suggestion. We have the Magnum BMS managing battery SOC pretty well, but I will check the bay and verify that nothing is going crazy down there. My casual observation is that that bay is pretty well isolated from the rest of the chassis and certainly the house, but hey -- worth a shot.

[Dtwallace]

Batteries will smell like collored greens cooking when being over charged. All it takes is one bad batt to do this, if that's the case.

[VP Chianese]

Originally Posted by nebster

Could the trap be dry if we run a load every day? And, if it were easily able to go dry, perhaps because of coach motion while driving let's say, wouldn't we expect to detect the odor in the washing machine cabinet much more than in the bedroom or the front of the coach? I was hoping washer would be the answer, but it doesn't make sense to me (yet).

The batteries are an interesting suggestion. We have the Magnum BMS managing battery SOC pretty well, but I will check the bay and verify that nothing is going crazy down there. My casual observation is that that bay is pretty well isolated from the rest of the chassis and certainly the house, but hey -- worth a shot.

Dry batteries will smell horrible if they are being charged.

[Sidewinder4]

Symptoms are exactly a match to the cheap vents for exhaust. Many have changed to this; cheap and inexpensive and most likely will resolve the issue. Have to buy self-leveling lap sealant as well. The link below is for Amazon, fixed my issue permanently. I replaced both of mine within 45 miniutes.


360 Siphon RV Fume Extractor - White - Rv Furnaces - Amazon.com;

[AKmtnpilot]

Had the same problem on a Vantana. Found that the end battery was getting hot and boiling and gassing. To make a long story short, check your batteries. Factory had hooked both the negative and positive to the same end of the battery pack. They should have placed the neg on one end of the batteries and the positive to the other end. Replaced two batteries under warranty, changed wiring, smell went away, and all is well.

[JLDHELMS]

Had the same intermittent smell issue in my 03 Dutch Star (black tank smell like sulfur dioxide, i.e. battery gas). Mostly going down the road. Tried every suggestion I could find, including wrapping the vacuum relief valve under the sink with plastic wrap. My problem was solved by a simple on the road trial repair. Bought a PVC T to fit the top of my black water vent pipe (on the roof), removed the factory cap and placed the branch side of the T on the vent pipe (run or open ends pointed front and back). Used silicone to attach the neck of a plastic bottle (the top funnel part!!) to the run side of T pointed towards the rear. This creates a vortex (suction) over the vent pipe as you move air thru the T. (Yes I know you can buy these contraptions for $20-$40 but I wanted to see if that was the source of my problem before I spent big bucks to retrofit all vents.) Worked perfectly. NEVER had odor problem again. Hope this helps. Jim

[redbaron73]

Originally Posted by Dtwallace

Batteries will smell like collored greens cooking when being over charged. All it takes is one bad batt to do this, if that's the case.

Reminds me of this episode from "The Office"

http://m.youtube.com/watch?v=o_DfrN_pBbs

2013 Newmar Dutchstar 4347, Active Air

[dennis45]

I get the same intermittent smell. Replaced sink check valves, new vent caps on the roof but the smell came and went.
Out of desperation, I got some plumbers putty and sealed off the drain hose off the washer where it goes into the stack. This helped but not a cure.
I have been using Happy Campers powder for years in my grey and black tanks but decided to run a scoop through the washer using a hot water cycle. No more smell. So now we run a scoop through about every 2-4 months and it seems to have fixed the odor problem. Just throw a scoop into the drum and run the washer through its cycle.

[nebster]

Hmm, thanks for all the tips, guys. I'm committed to the scientific method for this, so it's going to take me a while to figure out which thing is the cause. I have to work through all these different possibilities. :-)

[dav-cle]

I've had the same problem before. It's always the grey tank needs draining and cleaning. Usually happens on the open road and someone opens a window or vent..