Mahe 36: Diesel smell

[Rufduck]

Greetings,
Frustrating problem that is new for me but hopefully will ring a bell for someone.
I’ve recently developed a strong diesel smell in starboard engine bay, aft cockpit locker and stbd suite. Boat is a Duo, owners version, 2007 with D1-30’s.
I checked the primary filters on stbd side of aft locker and they appear intact, although I have trouble physically inspecting them.
There is nothing obvious on the stbd engine, no drips or oily areas around the injector plumbing. The sump under the engine has some water but when I dipped it with a stick, it didn’t smell like diesel.
A friend suggested that it might be the vent line from the tank and I’ll check it when I find it. It is suspect anyway because the tank likes to burp as it fills.
I also have a D4 Espar diesel heater that seems to operate as it should. Will try to access it’s fuel pump and delivery line. I hesitate disturbing it as the hot air hose is becoming brittle at the bends and replacing the hose will be a nightmare.

If anyone has any further ideas they will be much appreciated.

Cheers,
Martyn

[Rufduck]

Ah ha...found it.
Excess Fuel return line from injection manifold. Where the rubber hose clamps to the metal nipple is wet.
It is too short to clip and reconnect to the nipple without a strain. Will add a short extension via a brass splice.
Anyone know the diameter of the rubber hose?

Cheers

[weavis]

The smell of diesel in an older engine and assembly, is the singular reason I considered outboards on a catamaran.

Not my favourite eau de odour...

[Rufduck]

We looked at a number of cats before deciding on the Mahe. Outboards have their place and now the fuel injected versions give increased fuel efficiency, though none we looked at had them.
I did an engine remove and replace on my trimaran for under $2000 and prefer not to think about what it will cost on the Mahe but I do like 7-8 miles per gallon bucking headwinds and currents vs half that at best, and the fire issue, and 105amp alternators, and hot water and...;-)

Cheers

[weavis]

Originally Posted by Rufduck

We looked at a number of cats before deciding on the Mahe. Outboards have their place and now the fuel injected versions give increased fuel efficiency, though none we looked at had them.
I did an engine remove and replace on my trimaran for under $2000 and prefer not to think about what it will cost on the Mahe but I do like 7-8 miles per gallon bucking headwinds and currents vs half that at best, and the fire issue, and 105amp alternators, and hot water and...;-)

Cheers

The MAhe is an excellent model.
When I was in the States and had offshore boats, they were all petrol. I went on one diesel stinkpot, the engines were not tight and lacked love and care, and the diesel made it singularly unpleasant for the few days we were fishing..

Now with cats, I just do not want to smell diesel EVER... so Id be spending a lot of time and money keeping everything contained...

Yeah I know... Im a sensitive soul..

[Rufduck]

Well, shucks. After fixing the return diesel line, we had a fun day motoring and sailing with several friends. All went well until I shut down both engines and we began sailing. The strong diesel smell was back.

Mirrors and flashlight to no avail. Looks like the stbd stateroom inboard bulkhead is going to be removed to access the fuel tank fittings.

Will post what I find.

Martyn

[sailormed]

Clean suspected areas with laundry softener. It was mentioned somewhere on CF. I have not tried it yet.

[rabbi]

Originally Posted by Rufduck

Well, shucks. After fixing the return diesel line, we had a fun day motoring and sailing with several friends. All went well until I shut down both engines and we began sailing. The strong diesel smell was back.

Mirrors and flashlight to no avail. Looks like the stbd stateroom inboard bulkhead is going to be removed to access the fuel tank fittings.

Will post what I find.

Martyn

Just remove the panel. I have done that several ties and one gets used to it. Takes just a few minutes and you know whats going on.

Maybe the hose clamp of the diesel intake is loose. Or one connector at the pickup / return lines. We had a manual dipstick for the tank, in case you have an electrical gauge then maybe there could be another point of failure.
Not much else I can think of

[Rufduck]

No one said education is cheap but I now know a whole lot more about my Mahe.
The fuel smell was traced to the fuel bleed off manifold to return hose joint. After nine attempts to get it to reseal to the nipple, an email to a chap at Permatex brought a suggestion to seal it with Indian Head Gasket Shelac. Coat nipple, coat inside of rubber hose, wait 45 seconds wondering how long to wait and assemble. I let it cure for a couple of hours doing other chores and double clamped. Worked. No need to replace the whole return hose, I did.
But...in the process, I apparently levered and twisted the bleed off manifold and it started to leak at the #2 injector. Not sure where and worried I might crack the fuel line at the nut if it were too corroded, I purchased a replacement line. At the injector, use two wrenches, one on the nut below the fuel line nut and one on the upper nut. But, You can’t just remove the #2 line without a special tool to hold the lower nut on the pump. So all three are removed. Installed new line (the old was fine) and ran engine still leaks. In the process, I had inadvertently loosened the nut holding the bleed off manifold. There are three copper or aluminum squash seals that bear under the bleed off manifold banjo fittings that are in turn secured by a 17mm nut. No where is there a torque value for that nut. Note...over torquing the nut will make it leak at the seal ($16+ each). Torque lubed at 15 ft.lb., about the same as the fuel line nuts and a touch more if they don’t seal the first try. Replace all three seals and if you over tighten the nuts, you get to replace them twice, guess how I know. There are 11 places fuel can leak from between the injection pump and the engine. Btw, it takes less than 1.5 hours to remove and replace everything down to the bare injectors. It is straight forward but be both clean and methodical.
One more thing. The fuel bleed off return hose is a siphon from the tank. There is no shutoff except for the fuel feed. Both hoses need be closed to do the work above. I made a hose clamp from 2 pieces of oak 3/4” square and 3” long. Drilled and tapped one for a pair of 1/4 20 x 2.5” bolts and the other so the bolt was free to rotate. Clamp that tight on the return hose and the operation becomes much easier.
While I had the panel out between stbd berth and fuel tank, I replaced all the forced air heater hose, plus new double wall SS exhaust on the D4 heater.

Cheers, Martyn