Engine smell in rear bedroom

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amandaindc

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Apr 22, 2018
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Hi all - first posting but we are in dire need of some assistance! We have a 2003 Winnebago Journey 36DL with a Cat 350 diesel engine. We've had it about a year and have been battling a smell that originates in the rear bedroom. It smells of exhaust or "engine smell." It gets worse during mountain climbs. We had a problem with the seal on a bedroom window, and were hoping that was the reason the smell was getting sucked into the bedroom. But today we just did a test run with the window seal fixed, and we're still fighting the smell coming in. While my husband is driving, I have gone in the bedroom and put my face down in front of this vent panel under the bed (pic attached) and it seems like the smell is coming from there. (FYI, we have turned on the generator and a/c system while driving and this does not alleviate the smell.) Today we took off all the engine panels under the bed. The insulation looks good, and the seals look good except for one area where it is bunched up a little (pic attached). We are going to replace the seals and see if that was the problem. Is there anything else we can try to stop the engine smell from coming into the bedroom?

Thanks!
Amanda and Ken
 

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The place to start is not trying to block the smell, but stop it at the source. The fact that you're smelling more when the engine is working hard points to an exhaust issue (at least that's my thought, others my have additional ideas). You could well have an exhaust leak which could fill the aft cabin with carbon monoxide. I would get this checked ASAP (i.e., before your next trip) by a reputable Cat dealer (perhaps Empire, I believe they're nationwide). While I didn't have any noticeable fumes, during a recent service Empire Cat found a bad exhaust clamp on my Cat.
 
Also check the seals on the access ports in the bedroom.  I'm thinking that even if there were an exhaust leak it shouldn't get into the bedroom.
 
8Muddypaws said:
Also check the seals on the access ports in the bedroom.  I'm thinking that even if there were an exhaust leak it shouldn't get into the bedroom.
Click to expand...
Agree, but if there is a leak, fixing the seals doesn't guarantee that odorless carbon monoxide doesn't find a way to seep in somewhere
 
Thanks for the responses!
We do have a functioning CO2 monitor in the ceiling of the bedroom. Just went to test it and it is working properly with good batteries. It has never gone off even when the smell is bad. Maybe if the monitor was on the floor it might pick up CO2... ?

We did have Freightliner fix an exhaust clamp a few months ago, thinking that might be causing the problem. But it did not affect the smell at all. Then we fixed our window seal, but that didn't help either.

We're ordering the seals this week and hoping this helps! Otherwise we're out of ideas.
 
I would 2nd the recommendation to take  a(nother) look at the complete exhaust system.  I've had to replace portions of mine in my 2005 Vectra w/CAT 350 C7. 
 
We had a post here a while ago (2 to 5 years ago?) about the exact same problem but I don't remember the situation.  Try a forum search in the Winnebago board.
 
8Muddypaws said:
Also check the seals on the access ports in the bedroom.  I'm thinking that even if there were an exhaust leak it shouldn't get into the bedroom.
Click to expand...

The draft will pull it back under the chassis and there will be an area of exhaust concentrated at the back. That is much like the old station wagons,riding in them with the rear window rolled down.

On ours I had to seal the "dog house" under the bed when it made contact  with the rear and filled in a crack 1 1/2) where the cut out in the back is for the engine and radiator. Finally I found the tail light were leaking exhaust back into the living space and sealed them up.....good for about 4 cans of foam total.
 
We were beginning to have an exhaust smell with our Cummins, and the source turned out to be a cracked exhaust manifold ... common problem on the Cummins ISC.
 
We make sure all our ceiling vents are closed otherwise we've found it tends to pull smells from our tanks in.

Have you tried closing all vents and windows?

The vent you showed a picture of....I think I would temporarily tape a plastic sheet over it to see if that cures the problem.
 
The vent in the picture is for heat to get from the underside of the bed and also let heat into the basement of the coach, I think. You might have a leak in the basement area of your coach that needs sealing. By running your coach air you are just recirculating the air inside the coach. It also pulls some outside air into the coach. You can run your dash air on the regular setting, not recirculating, to bring in outside air from the front of the coach, pushing out the rear area air. I don't know if it has enough volume to push out the entire coach, but it might be worth a try.
Also, check at the back wall of the coach where the bed stand attaches to the rear wall. The screws sometimes come loose and allow air to get in. You will have to pull the mattress away from the wall to see the screws.
Good Luck,
Indiana Journey
 
Please get your exhaust checked at a muffler shop. A leak in your exhaust can burn a hole in the floor or start a fire if pointed the right way.
 
What you describe is not uncommon unfortunately. With a DP MH there can be a myriad of places for exhaust to seep inside. The best way to determine the location of the leak is to go to a party store and rent a "smoke machine". It uses a harmless chemical to make a smoky effect at parties.  Turn it on and place it under the motor in the back of the coach.

Close all windows and open the roof vents and turn the exhaust fans on. You may be surprised how many access points you find.  Foam seal the offending areas and repeat.  It's the only real and effective way to find a leak. 
 
My $.02 - While I try to save money all the time, I don't when it comes to my safety.  I don't know how you could smell exhaust and not have carbon monoxide.  Don't they come out together?

Please let us know the resolution and stay safe!  Get it checked out by a good pro!
 
Indiana was the only one to address that vent.. it not only vents the sub floor, but goes all the way across the bed base access and into the right rear bay where the inverter is located... thats where you should be looking for leaks. Its also possible you have an exhaust leak that is super heating the cabinet wall and burning the paint off on the inside. I ran into a guy in LaQuinta who had this problem and it melted his 50A cord. Someone needs to take a trip under the coach
 
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