Diesel smell

[jfschena]

Well I've been out sailing a few times. There seems to be a persistent diesel smell in the boat. When the seller delivered it, there was about a cup of mixed fuel and water under the stuffing box and engine. It was a warm day and a long road trip and the tank was full. I cleaned that up and went sailing. After a day of sailing with some motoring I found some leaks from a loose bleed fitting on top of the fuel filter and from the fuel line fitting (exiting I think) from the filter. I tightened everything up and cleaned the whole area in the picture with formula 409.

After the thorough cleaning, we ran the engine again and found no leaks. I thought I had this licked. We returned to the boat a week later and I found the area in the picture with a thin film of diesel.

It's been cold here. Do these engines hold fuel under high psi with the engine shut down? If so could it be that in combination with temps in the 30s that the fitting contracted and fuel weeped out? And what about that smell? Does it ever go away after the source of the leak is discovered and fixed?

Thanks

Joe

 

[DeniseO30]

you don't say what size boat you have. If you have the original fuel tank you may have pin hole leaks in the bottom where it sits on the plywood support. This is what happened on my boat. No leak showing.. just smell and fuel in the bilge behind the prop shaft but not quite under the tank. I replaced it all about 4 years ago with a new tank, lines, and pump.

 

[jfschena]

1984 oday 26 with a 1gm 6.5 hp yanmar. How did you identify the leaks in your tank? Was it a process of elimination?

 

[OdayDave]

Joe -

I've got an O'Day 25 with the 1gm1 (6.5). There shouldn't be anything under pressure. It's more likely that you just have a leaky hose somewhere. That happened to me last year and I ended up with a couple gallons of diesel in the bilge. Also look for holes in the tank as suggested above. Anyhow, I've cleaned up the mess and the smell is slowly going away. I used Dawn cleaning liquid in the bilge and lots of Fabreze. Clean your cushions well and the wall fabric if you have that. That should take care of it eventually. A lot less costly than a new engine.

Dave
s/v Lagniappe
O'Day 25

 

[jfschena]

Thanks guys. As a follow-up, do you turn off the tank fuel valve when leaving the boat for any amount of time? I did this once and had a difficult time starting the engine. We did some investigating and found the fuel filter dry. The engine started after manually priming it. I'm not sure if this is related to turning off the valve.

 

[DeniseO30]

well if the fuel is back by the shaft log and the engine is fwd of that, and the bilge slants down to under the engine. Is it wicking down the plywood and wood supports holding the tank? I was shocked when we found oil soaked plywood under my old tank. But that was on my boat which is an O30

 

[Stu Jackson]

smell cleanup: www.pureayre.com

Find the leak and fix it. Smells, noises and electrical issues without wiring diagrams are pretty impossible to help with on the internet. For fuel, you have a tank, an engine and the stuff in between. You're really the only one who can find it.

Also: careful engine inspection - watch it while it's running.

Good luck.

 

[Sailvayu]

Place small oil absorbent pads under areas where a leak could occur. Check back later and see if there are any signs of fuel. you may have to keep trying different locations till you narrow it down. Diesel is thin and will leak thru tiny openings. My first guess from what you say would be a bad seal on your secondary filter or the bleed screw. Bleed screws have copper washers and these tend to leak after a while.

 

[jfschena]

Thank you everyone.

 

[jibes138]

I just finished a project for the same issues. You probably have a small tank so loosen the hold down straps and tilt it up to see if it is corroded and if the wood supports are soaked. Look in the groove running down to your bilge and build a dam in there with clay or butyl tape. See if it slowly fills up.
If your hoses are more than about 10 years old rip them all out and replace them. They get brittle and crack. With the fuel pump on check all of them for leaks. The fuel circulates with the engine off so you don't need it running to check for system leaks.
As noted put clean absorbant mats all over the place and check for leaks that way.
Diesel smell will slowly go away but it takes some time. Seems to linger on your skin for a couple days regardless how much soap you use.
If the wood around your tank is rotted or wet then your tank is probably corroded. Look for any source of leaks that would cause the wood to be wet.
Good luck.

 

[odaydokay]

I have had this on my Oday 28 (1985) with Uni M12 Engine. Diesel Stink when coming on boat after winter, and first run or two in spring, then as weather gt warm it went away. All it takes is one loose or rotted hose, maybe higher than tank even, though not so if you have actual fuel in the bilge which I did not. This year I did not fill tank 100% full for winter (3/4 or a bit less) and no stink this spring. Cause and effect? Maybe, maybe not. Do check all the things other posters have noted, also the overflow outlet on transom, for blockage. Insects can clog that.

 

[jfschena]

Thanks again guys. I was at the boat this am. I dropped the fuel/oil filter housing down and the gasket looked in good shape. I cleaned everything as best i could. i ran the engine for about 20 minutes and it was bone dry. Maybe the filter ring was not quite on right. Well see next time I get to the boat.

I'm ordering new gaskets for everything that touches that fuel filter mount, including for the banjo fittings. I might even order new fuel lines.

Question: I noticed today I can't change the fuel filter unless I take off the exhaust hose and/or the throttle cable bracket. Has this been the experience of other 1gm owners?


The tanks and plywood and hull under tank are all clean and dry. Only a small amount of water collects under stuffing box--no fuel. All the seepage seems to be around that filter.

 

[Tom Potter]

I would try and redesign your setup so that you can easily change that fuel filter. You never know when you'll need to change it quickly. As Murphy's law has it, if it stops up and needs changing, its usually a inopportune time. I always carry extra filters and other supply's like belts and other stuff for those Murphy times.

I had a very small diesel leak last year. I traced it back to the tank. I ran my hand under the tank and felt the bottom of the tank and it was damp with fuel. There was a little corrosion with a very small pin hole. I ended up removing the tank and had the bottom cut off and a new bottom welded back. Much cheaper than a new tank.

Sounds like you found you source though.

 

[oldersalt]

Does your boat have any sound insulating material lining the walls of the engine space? When I first bought my old boat, I discovered that the old insulation, which included some kind of black foam-like material, was basically saturated with oil and diesel from years of use. After ripping it all out, thoroughly cleaning all the bulkheads around the engine, and replacing the insulation, the persistent diesel smell went away.
Good luck!

 

[jfschena]

Thanks again guys. I was at the boat this am. I dropped the fuel/oil filter housing down and the gasket looked in good shape. I cleaned everything as best i could. i ran the engine for about 20 minutes and it was bone dry. Maybe the filter ring was not quite on right. Well see next time I get to the boat.

I'm ordering new gaskets for everything that touches that fuel filter mount, including for the banjo fittings. I might even order new fuel lines.

Question: I noticed today I can't change the fuel filter unless I take off the exhaust hose and/or the throttle cable bracket. Has this been the experience of other 1gm owners?

Update. I called Mack boring and parts. I was trying to remove the filter housing then the filter. I should have been pulling the filter and housing down together. Well see if this works better.

Thanks for all your help.