Diesel smell in rear cabin.

Don S/V ILLusion · Jul 1, 2017

You didn't mention the tank vent line or whether you plugged it prior to pressure testing.

JamesG161 · Jul 1, 2017

Cross Linked Polyethylene can permeate. Most portable diesel cans are High Density Polyethylene.
It appears that vapor emissions from your type tank have been noted, by a quick web search.
________
I had the same smell on my metal tank. I later determined it was the rubber gasket on my diesel level sensor. I replace the sensor ( to modernize $80) and new gasket that came with it.

No more smell.
Jim...

PS: The previous owner found the, so called, leak, and tried to put a bead of silicon sealant around the gasket (amateur).

Benny17441 · Jul 1, 2017

Just one possibility. A fuel spillage which mixed with the water trapped in the stringers below the sole. Check for an oil film in the bilge water after putting the boat through some brisk motion.

kloudie1 · Jul 1, 2017

Shutoff valve packing oozing?

Neil Spooner · Jul 1, 2017

Thank you, but the bilge is dusty dry!
N

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Jerry Clark H356 SV Persi · Jul 1, 2017

My Hunter 356 2003 has no smells from diesel. I have 1308 engine hours and 3211 generator hours. My tank is stainless steel, not plastic. The holding tank is plastic. Also check the rear lazarette on your starboard side. If you had a filling overflow, you may have some residual fuel that got in the joint around the lazarette and has not dissipated. You should check the fill line (use a boroscope) and make sure you haven't worn a hole in it someplace. It would be difficult to visually check, but could be your source. I'd also check your Racor filter and around it and under it. Also recheck that your Yanmar engine filter doesn't have some residual fuel around it. It is very easy to spill some diesel when changing either filter, but particularly easy on the main Racor. It doesn't take much diesel to create a noticeable smell. Sometime someone has spilled some and you just haven't found the source.

You can buy a cheap boroscope with a light off Amazon that will plug into a Mac or PC using USB port. It's handy for checking out hard to get to places. I just checked Amazon and now they are wireless. $17 to $35 for various features and what it works with.

Jimongee · Jul 1, 2017

Tipsynippertoo said:
Hi Guys/Girls,
I have a Hunter 356 2002yr, and am trying to find where I am getting diesel smells from. The tank is a Crosslink Poly plastic tank made by Inca.

I have pressure tested the tank and fuel lines using a inflatable dingy pump to about 2psi, but can find no fuel leaks or air leaks using soapy water at all the fuel line connections on top of the tank, or the dry paper towel test on any of the hoses/injectors/fuel pump etc.

I have replaced the fuel return line from the engine which was giving out a slight odour, all the other fuel lines and tank seem to pass the "damp rag test".

The smell seems to be mainly around the aft end of the tank, and worse after the engine has been run for some time.

I am getting no fuel smells from around the engine or engine compartment.

I installed the Hunter mod' for an engine blower that runs all the time the engine is running.
Others have posted the same issues, but no-one has said they found the answer, except one person who never replied other than that they found the answer!
Love the boat........hate the smell!
Had the boat as second owner, previous owner never sailed it.......the smell has always been a problem.
Has anyone had similar problems with fuel smell "leaching" out of the plastic tank please?
Neil

Yes. I also have a 02 356 and I purchased it from original owner about 5 years ago. It came with the precise same odor problem you are experiencing. I solved it by literally taking my tools and going over virtually every single diesel fluid fitting. I did have to tweek a few of the fittings but never really felt I did anything useful. However it has been 3-4 seasons since that day and we have never smelled diesel in the boat again. It stopped after my alleged tightening. We noticed the difference immediately. Hope this helps
Jim
SV SamiDog
Boyne City, MI

Neil Spooner · Jul 1, 2017

Interesting, I had not come across any threads on diesel smell leaching through plastic tanks.
I used the vent line to pressurise the tank.
I replaced the Racor filter with a pair of Crossland, I didn't like the silly small space the Racor was fitted in, nor the filter. No smells from them as they are now in an easier access area.
I don't think the Racor filter was ever renewed with the previous owner, as the engine had only done about 50hrs!
Neil

Don S/V ILLusion · Jul 1, 2017

Neil Spooner said:
Interesting, I had not come across any threads on diesel smell leaching through plastic tanks.
I used the vent line to pressurise the tank.
I replaced the Racor filter with a pair of Crossland, I didn't like the silly small space the Racor was fitted in, nor the filter. No smells from them as they are now in an easier access area.
I don't think the Racor filter was ever renewed with the previous owner, as the engine had only done about 50hrs!
Neil

I assume you and "Tipsynippertoo" are the same person???
If so, that answers my vent line question.

Cross-linked poly tanks typically are impermeable to the volatile components of diesel (and most other things). Conversely, the foam in bedding, cushions, etc... can maintain the smell for prolonged period after even a small leak or spill by the previous owner and are more likely the (a) source of odor once you eliminate all others.

Peggie Hall HeadMistress · Jul 1, 2017

JamesG161 said:
Cross Linked Polyethylene can permeate. Most portable diesel cans are High Density Polyethylene.

There are two types of PE, James...Water and waste tanks are made of LINEAR PE, almost all low density because water or waste won't permeate it unless it's improperly cured (very rare, but can happen...ask Maine Sail) ...but fuel will permeate both low density and high density LINEAR PE. Which is why only CROSS LINKED PE, which has a molecular structure that's totally different from linear PE, can used for PE fuel tanks. However, PP (Polypropylene) and PVC can also be used for both gas and diesel tanks.

Now...to the question at hand... An often overlooked source of oil or diesel odor is drips from a dipstick...they can add up over time.

Peggie Hall HeadMistress · Jul 1, 2017

Tipsynippertoo said:
Do you know why you have a S'steel fuel tank and not plastic? Was it changed for this reason?

Tipsy's comment/question made me wonder... You said the odor seems to be emanating from around the tank. If the tank was replaced, there could have been a spill then. If so, I'm sure it was cleaned up, but spills, even small ones, leave residual odors that cleaning doesn't remove. So if you're sure that area is clean (if not, clean it), you might try treating it with PureAyre PureAyre ...just spray it on every surface, nook and cranny in that area and just let it dry. If that's the source, PureAyre will get rid of it.

JamesG161 · Jul 1, 2017

Peggie Hall HeadMistress said:
There are two types of PE,

There are many PE structures, but my point is....

I did a web search on the OP's tank and low a behold that tank maker had a problem with diesel permeability and enough so that EPA had listed them as an diesel fume emissions source.

Since I did minimum research as to the OP's tank year, I gently noted (my post#3) this manufacturer changed their manufacturing procedure and had recently been removed from the EPA list of hydrocarbon fumes emitters They use CROSS LINKED PE it did PERMEATE.

Who knows if his tank was in the emitter group of tanks?

Jim...

PS: 20 knot winds, hull speed run, sunny day, fresh air, family aboard. Anchored in Gulf, watched the fireworks display....

HAPPY 4th of July to all!!!

Peggie Hall HeadMistress · Jul 2, 2017

JamesG161 said:
that tank maker had a problem with diesel permeability and enough so that EPA had listed them as an diesel fume emissions source.

Your research only proves that anything can fail if it's improperly made, James... You're using the fact that one particular mfr's manufacturing process was obviously flawed as blanket "proof" that fuel can permeate any cross linked PE tank, implying that PE tanks are a risky, if not actually bad, choice fuel holding, which isn't true.

Jerry Clark H356 SV Persi · Jul 3, 2017

Tipsynippertoo: I may be wrong about my tank construction. My original recollection was it was stainless. I haven't looked at it in a while, but when I went back to my photos, now I'm not sure if it's metal or plastic. It's Grey and may be plastic. My photo is not a good one, but I am the original owner and this is the original tank. I'll recheck next time I'm on the boat and let you know for sure.
Where did you relate the Racor to?