Exhaust Smell while on Plane

D

Dalma

New Member
Jul 23, 2010
23
Ontario
Boat Info
2004 Sundancer 320
Engines
350 Mag V Drives
Hi All,

The Admiral asked me to ask all of you if this is normal. We have a 2004 320 with 5.7 mags and Vdrives. Whenever we are on plane (26mph) with canvas off we get a slight smell of exhaust on deck? Is this normal for this boat?

Also yesterday we went out to the sandbar on plane for about 15 minutes, with half tanks of fuel, and we were sitting on the swim platform (enjoying a bevvy) and we both could smell gas, I check down below, check the trunk, check the breather valve, but didn't see anything out of the norm and couldn't smell gas unless we were on the platform?

Thoughts?

Jay
 
Not sure if this is the same thing you meant by "breather valve", but the gas smell on the platform could be from the filler vent, since I think you would be sitting right next to the fill tube. Or the gas cap could have a bad seal and vent fumes from there.
 
Do you see any gas "rainbows" on the water surface when it's sitting still? I have never smelled gas while on the platform or anywhere else for that matter.
 
Tonka Boater said:
Do you see any gas "rainbows" on the water surface when it's sitting still? I have never smelled gas while on the platform or anywhere else for that matter.
Click to expand...

No Gas in the water, but I am going to check the seals around the gas filler caps...makes a lot of sense as they are both right where we were sitting.
 
Never smell the exhaust when running on plane. A few times with the wind in the right direction at 1600 rpm's could smell the exhaust. Maybe the rubber gaskets are missing from your fuel filler caps?
 
Dalma said:
Hi All,

The Admiral asked me to ask all of you if this is normal. We have a 2004 320 with 5.7 mags and Vdrives. Whenever we are on plane (26mph) with canvas off we get a slight smell of exhaust on deck? Is this normal for this boat?

Also yesterday we went out to the sandbar on plane for about 15 minutes, with half tanks of fuel, and we were sitting on the swim platform (enjoying a bevvy) and we both could smell gas, I check down below, check the trunk, check the breather valve, but didn't see anything out of the norm and couldn't smell gas unless we were on the platform?

Thoughts?

Jay
Click to expand...

Any chance there were waves? Peraps the gas sloshing around in the tank was pushing fumes out the vent port?
 
Although I do not have the same boat, if I leave my back cabin door open, my carbon monoxide detector will sound off due to the back flow from the back of the boat. Similar to leaving the back window down in a station wagon. I open my from hatch and I don't have the problem.
 
No exhaust smell on plane here either, and no gas smell while on the platform. The latter is the bigger concern...that really isn't right. Do you smell gas in the engine compartment?

-CJ
 
If you have a camper top with the front section closed and the back open, there will be a natural low pressure area in the back of the cockpit. This will draw in air from behind the boat and any exhaust fumes with it. I always open the front windows if the back is open to allow good air flow through the cockpit. If it is too cold or rainy for that, I leave the back up and open the front window vent just enough to provide positive fresh air pressue into the cockpit to avoid exhaust gases entering the area. Many inboard boats from Sea Ray are not available with factory camper tops for this reason. They have shorter "drop backs" instead.

When you stop the boat and get on the swim deck, the hot engine room causes the gas tanks to heat and the fuel in them to expand. That forces fuel enriched air to slowly exit the boat via the fuel vents. The vents are usually near the stern area so if the wind is right you may catch a wiff of those gas fumes while on the swim deck.
 
All great points above. However, the biggest puzzle is that what you experience is not normal and as you can see posts from 320 owners they don't have this issue. I didn't have it either. So, I'd say that something has to be fixed whether it's a leaking fuel that you don't see, leaking fuel tanks cap gasket or whatever it must be addressed. IF you can't find it, then get pros to help you.

In regards to station wagon affect Jim was describing, it does exist but it's not an issue as it can be managed easily with proper ventilation. When on a long trip all I needed is to have the back curtain rolled up and front vent open.

Z980_08-03_2009003.jpg
 
I have a camper top on my 360 and even with the rear glass rolled up and little forward vent open, I get some exhaust gas in the cockpit while running around 2500 and above. I like the idea of keeping the rear glass down, and vent window open, but that seems a bit dicey to ensure an adequate air flow. Are otners doing this with camper tops on their dancers?
 
There's no set rule, so feel free experiment what works best for you to keep your cockpit CO free. I used to ride having different panels rolled up at different times. It all depends on the weather and seas condition. The fact that all of my canvas panels had roll-up cutouts gave me all kinds of options. The most frequently used panels were the sides (usually the stbd). If it's hot outside I roll-up the port side and the back as well. When it's cold or raining I would button everything up and only use the front vent. At the cruising speed it provides enough ventilation when opened all the way.

To help me get better control on the CO level in the cockpit I've installed CO detector with digital display by the helm. It worked like a charm. By the time I feel like there might be some extra fumes it already beeps and I see how much CO is present. This is mostly helpful at slow speed (no wake zones) and wind behind you.
 
Thanks for all the great responses. So I had the tech's check out the gas smell and it was the seals around the gas cap and also they found a spider nest in the filler vent so they cleaned it out.

As for the exhaust smell, they said normal depending on weather, lake conditions, etc. However, another questions is my exhaust ports do not have any covers on them, should they? I looked at some pics of other boats and some do and some don't depending on year and model?

Jay
 
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