Gas smell in the cabin, new to inboards.

First let me start by stating I am new to inboards. I have had several outboard boats, including two cabin cruisers. Both were outboards. Both had tanks that sat outside. During the hot summer days you could smell a little faint gas smell as the tanks expanded. Nothing I worried about as I knew why they smelled and once we were underway or it was dusk it was gone.
I recently purchased a 81 34' Convertible with twin Crusaders. When I went to look at the boat the PO had just replaced the racor fuel filters. There was a strong odor coming from the engine bay. However once the cabin was open it dissipated quickly. During sea trial I mentioned the gas smell to the mechanic and surveyor and they attributed the smell to it being a gas powered boat. Neither had any concern. The mechanic did say that on the older carbs some of the linkage will get slightly lose due to normal wear. Once the shafts into the carb get worn you get some gas/vapor coming from those shafts. Well each day I have been back to the boat I am still smelling a faint gas fume. There is no visible gas leak from tanks, hoses, vents, etc. I do have just a little bit of water under the engines and I am actively working on tracing the source. It appears to be a thru hull but I am still determining that to be the case. Either way I see and don't smell any gas in the water under the engines.
Could I really be smelling gas coming from the carbs as residual vapor/gas in the bowl? I read on this forum once the carbs were replaced it went away. Could a simple new carb over fix that? I don't want to act paranoid but my whole family is going to be on this boat and some of our friends and relitives. I'd like to make sure it is safe!
Next month I have the boat scheduled for tank replacement as inspection holes were put into them and insurance, surveyor, and myself want those removed. I will have all new fuel lines at that time too.
Thoughts? Feedback? Also do those fume detectors work? Whats the best brand/set up for our inboards? Thanks!

Also,

Went I have the tanks replaced both motors are going to be out. What kind of work should I have done since they are going to be out of the boat? I am going to have the engine zincs replaced, thru hulls inspected, fuel lines replaced, other thoughts as to what to have done?

Greetings,
Engines out? Clean and paint bilges! If oil pans on those engines are prone to rust, remove, inspect and paint. Aw hell. Clean and paint everything that won't be accessible after the engines (re-painted) are back in.

Gas fumes in bilge can make a BIG explosion. Happens all the time. Just dumb luck when the perfect fuel-air mixture occurs near a spark.

I've had gas I/Os and I can't say I ever noticed a fuel smell, except after opening up the fuel system for some reason. Maybe I'm just used to the way engines smell. I'd think that any stray fuel left in the carbs would dissipate quickly in the heat of the engine compartment.

If you come back to the boat and consistently smell fuel, you're right to be concerned. It's interesting that the mechanic and surveyor weren't. Maybe calibrate your nose by checking out other similar boats. If yours is out of the norm, don't give up until you find the source.

You should not have any gas smell. Check vent lines on gas tanks make sure there is no cracks, also the fuel fill lines. Crawl around smelling to see if you can find the spot.

Smelling gas is not normal and indicates a problem. Not being familiar with Tolly's is there adequate ventilation? Did the PO block any of the vents to retain heat in the boat?

Your mechanic and surveyor saying it was normal makes me question if you are smelling gas or just normal oil odors. It often amazes me when I get gas odor complaints from buildings I'm responsible for that have no gas service ran to them whatsoever. Different folks have different senses of smell. On this theory I recommend when you arrive at the marina tomorrow open the gas cap on your car and take a whif then 5 minutes later go open your boat and compare the odors.

CPseudonym said:

Different folks have different senses of smell. On this theory I recommend when you arrive at the marina tomorrow open the gas cap on your car and take a whif then 5 minutes later go open your boat and compare the odors.

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Excellent idea, Craig!

Be alarmed. I have been involved in the aftermath of a gas powered boat explosion, it is ugly. If I smelt gas I would not hit start.
The mechanic`s diagnosis suggesting spindle leakage sounds more generalization than investigation and diagnosis; if right the carburetors should be repaired. Fuel injection might have been less prone to leaks.
As CaptTom says, you need just the right fuel/air ratio for an explosion. Too rich/too weak, no explosion, circulate some air thru the bilge and "too rich" may be "just right" ready for ignition. The exploding boat I knew was moved on the auxiliary engine with the "sniffer" reportedly showing "safe", air entered the bilge, the main engine starter was operated. BANG. Death of baby, multiple severe fractures of up to all 4 limbs in adults, deep seated infections from debris blasted into tissues, etc.
Not sure about gasoline, but some substances temporarily impair olfactory function, ie the ability to sense/smell them following exposure; they may be still present but undetected by sense of smell. Against this I`ve heard it said the best sniffer is the one on your face.
Just be careful.

Well I locked up the boat earlier this afternoon and sent the wifey in tonight to give it the thumbs up or down with a fresh nose. She turned it down. So, I will de-commission the boat until we get the new tanks in. I am going to have all new fuel lines, filler, tank put in. As well I will have the carbs double checked. In addition, have the bilge cleaned while the engines and tanks are out. If there is any fumes after that, well we know it's not gas! Either way, better to be safe than a story you read about thinking I saw a post by this gentleman. No way am I going to put my pleasure before my families safety! A real dissappointment as the weather is going to be stellar this weekend for boating but there will be many other wonderful weekends with our new boat ahead.
Back to my laundry list of things needing attention in the boat.....

Never smelled gas (except when fueling) in my Dad's sloop equipped with an Atomic 4 gasoline engine.

Still, I appreciate having a diesel engine now.

markpierce said:

Never smelled gas (except when fueling) in my Dad's sloop equipped with an Atomic 4 gasoline engine.

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Ditto here with my Owens and 350

On a gas boat the carb float bowls hold -1/4 cup of fuel , and they are vented to the atmosphere , so there is always some fuel that can be smelled .

Your nose is a fine instrument and can probably smell 1 /5000 of a mixture that could be a problem.Sniff an outboard that hasnt run in 2 decades , still the gas smell.

You shouldnt smell fuel (gas or diesel) as the cabin space should be sealed from the engine space.

Look for holes sloppy chopped that pass things added by unknowing owners over the decades.

Hang a 100W bulb in the engine space , and see where you can see the light elswhere on the boat.

Seal everything you see.

Correct me if I'm wrong but haven't seen where anyone has mentioned a fume (vapour) detector. I have had gas powered boats most my life, over 40 years, and always installed one in the bilge. Once it saved our lives. It went off while making way so I entered the bilge to find the gasket for the level float on the fuel tank had failed and I had just filled up with gas and gas was leaking out of the gasket. If hadn't been for the detector we may have been toast, literally. One of these should tell the OP if he has a leak. bshillam, do you have a vapour detector on board??

Allan

Great point

No vapor dector. I am also thinking that the floor boards literately on top of the engines are allowing those vapors from the carbs to enter the cabin as there is some sloppy boards there. Maybe some weather striping of some type to better seal the engine room access boards? The just sit against the floor grid with carpet wrapped around. Some thin weather stripping on all the surfaces should better seal that. I am thinking there is some additional work I can do to the floor boards to better seal them from the cabin.

bshillam said:

Went I have the tanks replaced both motors are going to be out. What kind of work should I have done since they are going to be out of the boat? I am going to have the engine zincs replaced, thru hulls inspected, fuel lines replaced, other thoughts as to what to have done?

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Engines out? If you don't have one, install an oil-exchanger system during re-install. Drains from the pan, not out through the dipstick, effortless oil changes. Each engine, genset, each gear.

-Chris

>If you don't have one, install an oil-exchanger system during re-install. Drains from the pan, <

I have not yet seen drain units with a remote , so this sort of valve will need one to reach under the hot engine pan to open and close the valve., if there is room for your arm.

The Tolly had a factory option for such. In an effort to make it easier should someone elect to order the option they pre plumbed the system from both engines to a panel in the engine room. If ordered they installed a pump connected to a switch on the helm panel and the oil would be pumped from both engines. There was a valve that had to be opened and then the switch turned on. I have everything with the exception of the pump. Should be an easy mod. Have to replace both lines running from the engines though as 30 years hasn't been kind. Soft and spongy hoses - YIKES with the oil from the engines.

Fume dector,
Fireboy MB1R Gasoline Fume Detector Blower Control - Fume Detectors by Discount Marine Supplies

Similar to what I was thinking of installing.

FF said:

>If you don't have one, install an oil-exchanger system during re-install. Drains from the pan, <

I have not yet seen drain units with a remote , so this sort of valve will need one to reach under the hot engine pan to open and close the valve., if there is room for your arm.

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FWIW, our units are plumbed from pan to manifold at the exchanger pump... and the valves are at that manifold. No valves at the pan, no reaching under hot engines.

-Chris

bshillam said:

I recently purchased a 81 34' Convertible with twin Crusaders.

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Howdy bshillam

I read every post on this thread. Much good input, many good suggestions!

Main item stated - to which I strongly concur - NO GASOLINE ODOR should be present on your engine compartment or anywhere else inside your boat... Period!

Seems you should/will/can take care of your gass odor by all the replacement/repair/modification work you are to accomplish.

Your, 81 34' Tolly convert/sedan has its engines in cockpit with v-drives and its gas tanks to rear area also... does it not? At least that is the way Tolly 34' converts were set up that I examined.

If you smell gas fumes in your cabin then there is a BIG problem occurring... I'm glad you decided to pull engines and put in new tanks. Can't go wrong there!

Engine and gas tank areas should always be well ventilated by the boat's side vents and your bilge blower should be able to refresh that area's air in ten minutes so that fumes are not apparent, even if they were, which they should not be in the first place.

Side note: Be sure to check into every cabinet, drawer, nook, and cranny aboard your Tolly. PO's have been known to leave small gas cans in the strangest places... just a thought?!?!

Best Luck!

Good point, I have pulled and opened all the compartments. I have founds some strange things. Still have to pull a few more drawers and look around. Haven't found any gas cans yet. The earlier Tollys had engines in the back. The 81 and up Tollys had them strait under the cabin floor. Not in the cockpit. I am not sure why they moved them. Maybe to get away from the v drive platform and move to a straight? I am going to seal the floor better though -

All great suggestions. By the time I am done with the tank repair, minor here and there repairs (that I want the shop to do) and the gel coat repair I'll be well over $10k on that bill.....welcome to boating!

B reak O ut A nother T housand

beachbum29 said:

B reak O ut A nother T housand

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I think they should change the name to BOMT....Break Out Many Thousands!!!!.....BOAT is so outdated!!!

Greetings,
Mr. b. Just for fun, hold off on sealing the floor until all the other work is done. IF the gas smell is still there, you've got more work ahead of you (I suspect it won't be there but...). No sense eliminating a known "telltale" (smell of gas through the hatch) just in case.

BTW - As has been eluded in posts on this and in other threads... "The Nose Knows!

As long as your olfactory nerves and sences are working well... There is no other "Gasoline Fume" detector better than your nose. IMHO

So - Here is how I handle things re gas fumes in my bilge compartment, i.e. engine and fuel tank areas:

1. Run blower ten minutes before starting engines or activating any other ignition source in bilge... that includes even within just a couple hours shut down after running engines

2. As blower begins running place nose near an air-exit vent on boat's side and carefully smell for fumes... My Tolly makes that simple due to vent locations

3. When filling tanks always open at least one engine hatch during fill up and after filling bend deeply into engine compartment for a deep breath. Then close hatch and turn on blower for appropriate length of time.

I believe that if you keep all items for gasoline storage, transfer, and burn in engines in good shape... and... by adhering to #'s 1-3 safety measures that the chances for explosion are virtually eliminated.

Of course a real good vapor detector (if per chance a sudden, unexpected big gas leak happens while underway) is also a very good item to have ready and waiting for warning actions.

Happy Tollycraft Boating Daze!

bshillam said:

No vapor detector. I am also thinking that the floor boards literately on top of the engines are allowing those vapors from the carbs to enter the cabin as there is some sloppy boards there. Maybe some weather striping of some type to better seal the engine room access boards? The just sit against the floor grid with carpet wrapped around. Some thin weather stripping on all the surfaces should better seal that. I am thinking there is some additional work I can do to the floor boards to better seal them from the cabin.

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If there are gasoline fumes in the bilge/ER reaching the cabin above, you surely want to know. Additional sealing may hide their presence compromising safety. Follow your intention to find and fix the source, and fit a detector.

Mr. K Post #24...

RT Firefly said:

Mr. K Post #24...

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Indeed, great minds etc, no idea how I missed yours before posting.

I hope there is no miss understanding, all lines, and both tanks will be replaced as well as an active fume detector will be installed. No chances with my life or my loved ones. I am just thinking of better sealing the ER from cabin.

Buying a project boat will lead to the unforeseen appearing time and time again. As previously suggested once all the tanks and engine gear are removed you will have a great opportunity to make it right, especially the potentially gas saturated ER wood which is abundant on Tollies. What material were the old tanks and what for new again?

Yesterday I was on a very nice 1989 Tolly 40 sport fisher. DD 400 hp 6 53s with no smell, major oil drips or fuel leaks. The PO was very careful and attentive. But it will need new engines in a few years too, at a lot more cost than the gassers you will put in.

Many good boats have V drives, just be sure those have been gone through too. Enjoy, many of us have been in your shoes wondering what we got into with this old boat.