Diesel fuel smell coming thru head

Jul 24, 2019
2
Hunter S30 Pt Richmond, CA
Hi all - I had my 1990 Hunter S30 out in fairly blustery weather a few days ago. When we returned to port we noticed the head had flooded out a bit into the main cabin and there was a strong exhaust smell. I've checked the gas tank, all connections to the tank, run the engine and don't see any leaks. Went back to boat, ran the engine for about 20 minutes, flushed the head a few times after filling several times with water -- still noticing when I dipped a cup in that fuel seems to be in the head water. I don't see any place these two systems connect. Any suggestions or ideas? Thanks!
 
Sep 25, 2008
7,077
Alden 50 Sarasota, Florida
Just a wild guess but I don’t think they are connected:waycool:.

From where does the flush water come?
 
Dec 2, 1997
8,709
- - LIttle Rock
Hi Eva...I see you've just joined sbo.com today...welcome aboard!

I can only guess.... To me this sounds like there has to be a fuel leak somewhere in the system. Fuel is leaking into the bilge where the bilge PUMP is sending it overboard around your boat...you can confirm this by looking for a fuel slick around it. If you're leaving the head intake seacock open all the time, even when away from the boat, water with fuel in it is getting into the toilet intake line...flushing the toilet is pulling it into the toilet.
As I said at the start, I'm only guessing...but unless a boat next to you is the one with the fuel leak putting it into the water for your toilet to pull in, this is the only thing that makes any sense to me.

If your fuel really is gas, not diesel, it's also making me very nervous 'cuz gas fumes are highly flammable...any spark, even just static electricity, can explode and you haven't mentioned running any bilge blowers to expel the fumes before starting your engine.

But that's not the only thing that bothers me a lot:
When we returned to port we noticed the head had flooded out a bit into the main cabin
That tells me that not only are you leaving the toilet intake thru-hull open all the time, even when away from the boat, but there's no vented loop in the toilet intake either, That combination along with relying on remembering to always leave the the wet/dry lever in the dry mode is just asking for your boat to sink in its slip...you've already seen it overflow the toilet into the cabin...Had that happened while you were away from the boat, it would have sunk in its slip!

So I'm very glad you decided to join our merry band today...'cuz there are a lot of people here who can help you find and eliminate your fuel leak and I'll be glad to teach you what you need to know to prevent water OUTside the boat from using your toilet to bring enough water INto your boat to sink it.
Again...welcome aboard!

--Peggie
 
Oct 9, 2008
1,739
Bristol 29.9 Dana Point
Did you visit the fuel dock before you went out?
The fuel dock boys might have put diesel in your holding tank.
And then were silent about the mistake.
To some, all deck fills look the same.
 
Dec 2, 1997
8,709
- - LIttle Rock
Interesting guess, but the fuel odor is in the flush water....toilets don't pull flush water from the holding tank unless a serious plumbing mistake has been made.

That said, dock hands aren't the only ones who can put the wrong thing in a tank...I once put 35 gallons of water in my starboard fuel tank. It would have been a lot more if my husband hadn't noticed that the fuel gauge for that tank was showing 3/4 full when the port gauge was showing only 1/2.
--Peggie
 
Oct 9, 2008
1,739
Bristol 29.9 Dana Point
Interesting guess, but the fuel odor is in the flush water....toilets don't pull flush water from the holding tank unless a serious plumbing mistake has been made.

That said, dock hands aren't the only ones who can put the wrong thing in a tank...I once put 35 gallons of water in my starboard fuel tank. It would have been a lot more if my husband hadn't noticed that the fuel gauge for that tank was showing 3/4 full when the port gauge was showing only 1/2.
--Peggie
It of course was not assumed that she was pulling flush water from the holding tank.
I was thinking that if there's diesel smell in the head, it may be coming from the tank, even after flushing. Those joker valves never get replaced. ;)
 
Jul 24, 2019
2
Hunter S30 Pt Richmond, CA
Hi everyone:

Thank you so much for the replies! All are so helpful! So I "inherited" PAX via a tough personal situation and she was let sit for some time by prior owner and I am catching up on a lot of maintenance. In the past 6 months (Ka Ching!) I have replaced the mainsail and headsail, had her demasted and spreaders repaired, derigged and rerigged her, replaced the ancient roller furling... and now just when I got help to get up the new mainsail this new problem of the stinky fuel floating in the head appears! I am learning as I go, just got ASA Certified for Keelboats 101, working on 102. So I'm a newbie AND I don't really know how to use this forum... hoping I am answering all here!

- It is definitely diesel fuel as I know the boat takes Diesel. Check.
-Last year I had the joker valve on the head replaced/repaired.
- Good point (Peggy?) about making sure the toilet valve is shut off when not using boat. I've never done that -but I know where it is. :)
-Re the Bilge, there is not much water in there - maybe an inch or two? So I have not run the bilge pump for some time. When I start the boat, should I let her run for 10 minutes or so, making sure the port holes and airways are open so she can vent a bit? Also, should I automatically run the bilge pump too? (I have read in my ASA training that I should "Run the pumps" to clear fuel but I don't know what pump is being referred to.
- I "thought" the flush water comes from the bay itself as I know there is as noted the "wet"- "Dry" option on the flush side... I thought one side is to empty offshore on the bay, and another is to empty into the holding tank.
- I do not "think" anyone put fuel in the holding tank by mistake as I haven't had her at a fuel dock - you are right - both caps look very similar (fuel and holding tank). I have extra fuel on board however, and it could be that someone tried to top off the fuel to be sure in the wrong side.
- RE: Peggy's suggestion to look for gas slick (assuming bilge pump was pulling in a gas leak" I will do that!
I think my next step is to take her to the holding tank clean out dock and empty her out and flush the tank system with water a few times, clearing all of that out too.

It's not "pure diesel fuel" in there - more like a mix of fuel floating in the water.
I have the water schematics for the boat, but am having a hard time reading it.

Thanks for reading this TOME all. Lol. I tried to reply to each of you but it puts me on the bottom of the threads every time.... I am "replying to thread" here.

MANY THANKS!!! I am headed to boat tomorrow and will review all of your comments and report back. :)
 
Dec 2, 1997
8,709
- - LIttle Rock
You're doing just fine at using this forum...post questions, read answers and post followup questions. I've specialized in sanitation systems (toilets and related equipment and plumbing) for 30 years, so I'll mostly limit my advice and answers to helping you get that system working as it should and let others who have a lot more experience and expertise in other systems help you with those.

- I "thought" the flush water comes from the bay itself as I know there is as noted the "wet"- "Dry" option on the flush side... I thought one side is to empty offshore on the bay, and another is to empty into the holding tank.
Nope. The toilet does pull the flush water in from the bay, but it's the toilet pump, not the bilge pump, that pulls it in. The wet/dry lever only controls flush water...blocking it in the "dry" mode, allowing it to come into the bowl in the "wet" mode. Pumping the toilet in the "wet" mode simultaneously pulls flush water in and pushes bowl contents out...pumping in the "dry" mode only pushes bowl contents out without bringing in any flush water. And btw, marine toilets are not designed to bring in flush water and hold it in the bowl.
Whether the flush only goes to the tank or can also go directly overboard depends on how the system is plumbed. The hose from the toilet to the tank may or may not have a valve in it that provides a choice of flushing into the tank or directly overboard--which can only be done legally in open sea at least 3 miles from the coastline or any island.
While you're on the boat tomorrow, get a photo of your toilet that clearly shows the pump (all bowls look alike)..take it from above. That'll let me ID it. Spend a little time exploring the toilet plumbing to learn where all the hoses go...take photos of any valves, tees or wyes that have hoses running off them and also make note of what the other end is connected to. Unless your ability to draw a diagram is even worse than mine, diagrams will help a lot!

At the risk of being accused of trying to sell you something, I strongly recommend that you get a copy of my book (see link in my signature below my posts). The title (my publisher's idea) is a bit misleading...'cuz although it does deal with every source of odor on a boat and how to cure, or better yet PREVENT 'em (information you'll definitely need sooner or later), it's actually a comprehensive "marine toilets and sanitation systems 101" manual that explains the laws, describes all the types of systems and how they work, and will help you learn how to operate and maintain your system to prevent 99% of problems instead of having to cure 'em. And I'm always glad to answer any questions it doesn't!
--Peggie
 
Dec 28, 2015
1,837
Laser, Hunter H30 Cherubini Tacoma
Have you pumped the holding tank since acquiring it? If not, I’d do it and start from a known beginning, the tank does not have fuel in it.
If it was the source I would think it might be a kerosine or something else the previous own flushed down to maybe clean the system or lub it in error.
 
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Likes: BrianRobin
Jun 8, 2004
10,024
-na -NA Anywhere USA
I was curious. Did the previous owner by chance fill up the wrong tank with diesel fuel and not remove it. Pump the head tank out and see.