Fuel smell

As I mentioned in an earlier post I am planning on purchasing a trawler. Looked at many and have learned alot both from looking as well as this forum. Receintly we found a fit except for the smell of diesel fuel The first time I looked at the vessel I did not notice the smell. This time the smell was quite strong. I also remember that other trawlers had the same smell. The obvious answer is a leak in the fuel system. This is an 81 clipper and tanks would be a major concern. I am told the tanks are coated inside and out. I am also told by the owner that there are no leaks in the system. Is it possible the vents could allow the smell to permiate the salon? Where are they and could wind or lack of be the cause. What about this coating? Was that standard or was that to fix a leak? and what kind of job is it to replace two 120 gal tanks? My bet is major.
Ken

1. Before you go any further, have the boat surveyed by a reputable marine surveyor. He or she should find any problems with the fuel system and note them on the survey. The owner is trying to sell a boat. He/she may say anything to sell the boat.

2. The vents cannot cause a fuel smell to permeate the cabin. The vents are outside the hull.

When I first bought my old Mainship, it smelled like diesel all the time, even after fixing many leaks. When I replaced the old Perkins with a new Cummins, the smell was no longer there.
I'm not saying then Perkins are smelly, just that old engines can be. Once there are a few fuel leaks, it's very hard to get all the fuel cleaned up.
My current old Lehman does NOT smell like diesel.

rwidman said:

1. Before you go any further, have the boat surveyed by a reputable marine surveyor. He or she should find any problems with the fuel system and note them on the survey. The owner is trying to sell a boat. He/she may say anything to sell the boat.

2. The vents cannot cause a fuel smell to permeate the cabin. The vents are outside the hull.

Click to expand...

Old fuel hoses can put off a smell as the diesel will eventually permeate them if they're old.I would be concerned about coated tanks.Why were they coated?Was it to stop a leak,preventative measure?It's hard to judge how big a job it will be to replace tanks.Things get changed on boats,upgrades are made,accessories are added.All of this could hinder removal and install.

kpinnn said:

As I mentioned in an earlier post I am planning on purchasing a trawler. Looked at many and have learned alot both from looking as well as this forum. Receintly we found a fit except for the smell of diesel fuel The first time I looked at the vessel I did not notice the smell. This time the smell was quite strong. I also remember that other trawlers had the same smell. The obvious answer is a leak in the fuel system. This is an 81 clipper and tanks would be a major concern. I am told the tanks are coated inside and out. I am also told by the owner that there are no leaks in the system. Is it possible the vents could allow the smell to permiate the salon? Where are they and could wind or lack of be the cause. What about this coating? Was that standard or was that to fix a leak? and what kind of job is it to replace two 120 gal tanks? My bet is major.
Ken

Click to expand...

Ken the outside of the tanks should be painted grey, as mine are. Before spending the money (just yet) on a surveyor, make sure you look for leaks (Bring a flash light). I have an access panel under my settee on the starboard side. Open the cabinet and see if they have that same access panel to the top of the tanks.

As far as removing the tanks, the Tung Hwa Clipper has VERY easy access with tons of storage. When the time comes, I will have mine cut out and replaced with two smaller tanks to each side.

A LOT of things can make a boat smell like diesel...including the one next door if their startup fumes fill your cabin each time...

I wouldn't waste my money yet on hiring any pro to track down a leak you can probably see yourself or sniff out. Yes when the time comes to purchase and the fumes are your only question mark...then paying a pro to help you out would be a good idea (but you will hire one at that point to get insurance anyway I suspect.

The only time the smell would be a hard on to fix, though replacing tanks could be a big deal depending on the boat, would be if a lot of wood was saturated with diesel. Minor leaks are easily solved yet sometimes hard to find unless the boat is running a lot. Tank leaks oozes are a problem that also can be hit or miss depending on where and what they are...sometimes the fix is easy...all the way to replacing tanks which may not be as bas as you think and certainly in the negotionable price of the boat...as long as they are found prior to purchase.(even ridding the boat of the smell can be negotiated...especially now as many bats are finding a tough time being sold).

Thanks everyone, great suggestions. Not much has been added to this boat and it was well cared for. Yes I will hire a survey once we agree to a beginning price. Regarding the vents, I assumed the vents were outside but were in relationto the windows. The first time I saw the boat it did not smell. Most of the windows were closed and the engine had not been started. I suspect the smell has something to do with the startup and windows being open and not moving the boat. Good to hear that this boat typically is not a "Cut the deck and remove tank" situation. Also on another subject: If anyone has experience with seakeeping properties of a 30 ft Clipper I would certainly like to hear about them.
Ken

To build on what Pnsneeld said earlier, a fuel smell can come from a ton of sources. A fuel tank leak is not what I would suspect first unless it's obvious that's where the fuel is coming from. Fuel fumes are like blood-- it doesn't take much to seem like a lot. So even a weeping connector in a fuel line, a "wet" joint in fuel filter, a weeping injection line connector, and so on can generate a strong smell in a short time.

If you really want to get serious about finding a fuel leak, diesel fuel glows blue under a black light. It's how the diesel shop we use pinpoints leaks in injection pumps, hoses, etc. where the source is not obvious.

Look at the tanks, get their measurments and see if you can figure out how they could be removed. On our 34LRC Californian after doing same, it became obvious we would have to cut the deck or cut the tank. After further measurment it was questionable if they would come out even by cutting the deck without cutting a major cross section support beam, so we cut the tank. I built a mock up, 2 by 4 frame to see what the largest one I could get back in there and than built another but smaller one to come close to the original tankage. Cheaper to do it that way as well, considering the cost of fiberglass work that would have been required if we cut the deck.

Marin said:

If you really want to get serious about finding a fuel leak, diesel fuel glows blue under a black light.

Click to expand...

Here's the one I put in my pocket when attending a boat. It is the best leak finder since bubbles.

Handheld Flashlight, Combo UV Auto/HVAC - Handheld Flashlights - Flashlights - 2XUZ3 : Grainger Industrial Supply

Get a jar of fluorescein dye tablets and you can find water leaks as well.

If you really want to get serious about finding a fuel leak, diesel fuel glows blue under a black light. It's how the diesel shop we use pinpoints leaks in injection pumps, hoses, etc. where the source is not obvious.[/QUOTE]

This I did not know. I've got no leaks that I know of but I'm going to try this out.

Baggiolini said:

This I did not know. I've got no leaks that I know of but I'm going to try this out.

Click to expand...

The system has to have had dyed fuel at some point or you might not be able to see it. There are dyes made to add to the fuel for leak finding that really glow brightly.

Coolant leaks also show up well.

Fighterpilot said:

Look at the tanks, get their measurments and see if you can figure out how they could be removed. On our 34LRC Californian after doing same, it became obvious we would have to cut the deck or cut the tank. After further measurment it was questionable if they would come out even by cutting the deck without cutting a major cross section support beam, so we cut the tank. I built a mock up, 2 by 4 frame to see what the largest one I could get back in there and than built another but smaller one to come close to the original tankage. Cheaper to do it that way as well, considering the cost of fiberglass work that would have been required if we cut the deck.

Click to expand...

How did this go from a smell to cutting out the fuel tanks?

RickB said:

The system has to have had dyed fuel at some point or you might not be able to see it.

Click to expand...

Oops, got to thinking about that and ran a little experiment, I was wrong. The photos show a sample that has never been anywhere near dye. One picture under normal lighting, the other under UV.

Sorry for the blurred UV but the camera was handheld with very little light.

Lube oil leaks also show up.

I'm curious--- the diesel shop said that fuel "glows blue" which I took to mean that under the black light the fuel would be blue but nothing else would. So on our FL120s which are painted Alpine (Detroit) Green, I took the shop's statement to mean that fuel weeping out of an injection pipe connector on the injection pump would "glow" or reflect blue but that nothing around it would turn that color. So the injection pump would remain dark while onliy the weeping fuel would show up blue. If everything turned blue you wouldn't be any better off than before.

So what has been your experience with this? Does fuel on an engine block or injection pump turn blue while the surrounding metal reflects no light at all?

Marin said:

So what has been your experience with this? Does fuel on an engine block or injection pump turn blue while the surrounding metal reflects no light at all?

Click to expand...

The fuel glows blueish, lube glows a weak green, and coolant looks kind of whitish green to glaring green depending ( I guess) on the additives and base.

The fuel in the photo shows up really well because it is in a glass jar and totally illuminated by UV only, the best condition possible for a demonstration. Real life isn't always so distinct but a little practice and the right amount of dark will generally work really well. If I were seriously looking for a minute leak I would dose the fuel with one of the several fuel dyes made for leak finding as they will glow very brightly and remove all doubt about what you are seeing. I have some around here somewhere, I will see if I can do another demo showing plain fuel on a surface vs some with tracer dye. Don't look for it tonight though.

Some paints glow bright white most stuff doesn't fluoresce at all so there isn't any difference. Soup on a white shirt and squirrel pee really shows up!

It is kind of fun to see what does what.

As was said before with diesel (and gas for that matter) a little will go a long way in the fume aspect. If the owner did any filter changes lately and spilled a few drops you can smell it. also whatever is used as a catch can when your filter bowl is drained can have some residue that will off gas enough to be detectable. If any was spilled on the carpet, well now you've essentially got a diesel soaked rag in the salon! When it comes to dealing with anything on a diesel fuel system cleanliness is second only to care taken not to spill any. I put paper towels around everything when I break into the fuel system. Clean up any spilled fuel immediately so it can't soak in. A closed cabin, summer heat,and a little gaseous petroleum product can sour a potential purchase FAST!

rwidman said:

How did this go from a smell to cutting out the fuel tanks?

Click to expand...

The OP posted in his original post...

" Was that standard or was that to fix a leak? and what kind of job is it to replace two 120 gal tanks? My bet is major.
Ken "

I recently dealt with this same problem.... In our case it was strongest after an engine start-up and running. I could smell it, but couldn't find it...then one day... my starboard engine stalled a few times...once or twice maneuvering in locks.... That did it. We docked and I went below and got up close and personal with the fuel system... Long story short...the fitting for one of the injector lines was just loose enough to allow a little weepage...and in the heat of the engine room...the fuel evaporated quickly.

Tightened the fitting...weepage stopped, no more diesel smell...

twiisted71 said:

As was said before with diesel (and gas for that matter) a little will go a long way in the fume aspect.

Click to expand...

Diesel fumes on a boat are an annoyance. Gasoline fumes are a hazzard. A serious hazzard. Something that must be addressed NOW!

One advantage to keeping your boat's bilge, engine, etc. clean is it's far easier to spot any leaks.

For anyone who suspects an actual leak in a fuel tank, there are professionals with the equipment and expertise to pressure test fuel tanks without damaging them. Also, depending on the location of a tank leak, it may take a certain level of fuel before it leaks out.

Marin said:

If everything turned blue you wouldn't be any better off than before.

Does fuel on an engine block or injection pump turn blue while the surrounding metal reflects no light at all?

Click to expand...

I just reread your post and looked at the photos and see what I think you may be seeing and I should have (no pun intended) highighted ...

The fuel will glow but nothing else around it unless that material itself will fluoresce, which most things don't. A drip or run of diesel will glow but the metal around it won't.

If the paint color is close to the color of the glow it can be very difficult to see. That is why the tracer dye helps because it makes fuel stand out from any normal background.

The blue saturation shown on my picture is because the only illumination was from the UV light. The paper towel glows bright white in UV, the fuel was glowing bright blue and the transmitted light made the surrounding white paper and the background appear blue.

The camera chip may also be more sensitive to UV or blue spectrum light than the eye so that may increase the blue saturation but you are the expert in that area, not me.

rwidman said:

Diesel fumes on a boat are an annoyance. Gasoline fumes are a hazzard. A serious hazzard. Something that must be addressed NOW!

Click to expand...

My point was that they are very gaseous products and that it takes only a miniscule amount to "fill" an enclosed space such as an engine room or salon withdeal breaking fumes. This wasn't began as a safety thread.

Rick--- Thanks for the follow-on explanation. With a 39 year old boat and engines--- albeit with a fuel system (tanks, hoses, and fittings) that were installed the year before we bought the boat in 1998--- it might be prudent to have a blacklight on board.......

If you think it is worthwhile to do the occasional leak survey, buy a couple of the little tiny vials of diesel leak tracing dye. It only takes a few drops in a tank to make it easy to find leaks.

Google, diesel tracer dye for a quick course.

Thanks, I'll check it out. So far we've only had two instances that I can recall of fuel leaking. One was a weeping connector that holds one of the injection pipes to the top of the injection pump. Tightening it solved that. The other was an injection pipe (not the same one) that pinholed and was shooting a thin stream of fuel against the side of the engine. Replacing the pipe solved that. In both cases, the giveaway was an immediate diesel smell noticeable in the main cabin.