Atomic 4 Gas Fumes

[Katie Jennings]

New owner here... We have a 1971 E29 with an Atomic 4 that's still chugging along. Only problem is, after it's been closed up for a little while we open the companionway hatch to noticeable gas fumes. Is this normal, or should I be looking for leaks?

 

[paul culver]

I have the same boat and engine but not the fumes. Definitely check for leaks, from fuel tank to carburetor. If you have the original mechanical pump and its leaking you should consider replacing it with the electric pump upgrade. Moyer Marine is the best site for all things Atomic 4. The forum is packed with info and you can even call Mr. Moyer with questions.

 

[Chris Mc.]

Old gas engines have a tendency to smell like old gas engines. As previously suggested, the carburetor is where I would start. It could be a combination of the float bowl gasket being old and seeping as well as the float needle isn’t seating correctly allowing excess fuel into the intake. Fuel pump and clamped connections in the fuel line-as well.
Definitely be sure to use the blower for venting gas fumes before start up!

 

[Afrakes]

Also make sure that your fuel lines are not saturated. Long ago. when I purchased a 73' E-27 there was the distinct odor of gas but no visible leaks. When I checked the rubber gas lines I found that they were saturated. I pinched them between my fingers and smelled gas on them. Ripped out and replaced the old lines and the problem was solved.

 

[Kevin A Wright]

The carburetor float stuck on my old E27 and even though I had the fuel line shut off the shutoff didn't work evidently. Came down to the boat to find a half quart of gas in the bilge. Lucky I don't smoke. This was about a month after another boat blew up in our marina from gas fumes in the bilge. blew the ports halfway across the marina.

Solved the problem by putting in a new diesel to replace the A4 which was on it's last leg anyhow. Never regretted it.

Kevin Wright
E35 Hydro Therapy

 

[toddster]

It's not "normal" but it sometimes happens. Closely examine all the fittings in the fuel line / filter / pump sequence. (There should be as few of these as possible.) There may not be any "drips" because the leak is so slow that it evaporates as it happens. I've had two of the "fuel shut-off valves" from NAPA start leaking after a winter (maybe temperature change has something to do with it?) The one from Apollo doesn't ever seem to have a problem. Sometimes the thread sealant used to install a fitting wasn't the right stuff for fuel. Again it seems to start after a winter. If there's dust and grime on the engine compartment floor (of course there isn't...) look for signs of a slow drip disturbing the dust.

 

[Parrothead]

In addition to the good advice offered, if you have a mechanical fuel pump the USCG requires errant fuel resulting from a pump diaphragm breach to be pumped into the crankcase for containment. As indicators check the oil level (unusually high = gas getting in there) and smell the dipstick. Whatever you do, don't quit until you find the source of the smell. A properly maintained gas engine has no odor. None.

 

[Katie Jennings]

Thanks for all these thoughts.

I had our engine mechanic give her a good looking over and all seems to be in good running order.

Findings: if I regularly wipe down the engine compartment with fresh water/vinegar, and use the blower regularly, problem is solved. We just spent a week in the San Juan Islands (4 people sleeping aboard) and weren't bothered. Also key is to keep the blower going at all times when the engine is running.

 

[kapnkd]

New owner here... We have a 1971 E29 with an Atomic 4 that's still chugging along. Only problem is, after it's been closed up for a little while we open the companionway hatch to noticeable gas fumes. Is this normal, or should I be looking for leaks?

No, it’s not normal.

IF you have the old factory designed standpipe that was wrapped in asbestos as well as the cross piece coming from the engine - chances are the pipe has deteriorated (as ours did) and the only thing containing the fumes is the asbestos wrapping, which can/does “blow out” with exhaust pressures.

We repowered years ago and replaced our original standpipe with an Aqua Lift system which has been trouble free to date.

My E-32 manual has the specs for the standpipe (probably the same??) should you wish to build a new one ...and we’re happy to share if you need???

 

[toddster]

Ah... engine blowby (combustion fumes) is a different problem than gas fumes. You really want to track down and eliminate any fuel leaks.

If it's combustion fumes - one thing to check is that the little vacuum line from the manifold is intact. Vacuum lines aren't usually very tight, but they shouldn't leak. The A4 recycles some of it's blowby through the little rubber hose that recycles gases back to the intake, through the flame arrestor. It seems like this thing inherently leaks, especially if vacuum is low.

Indigo Electronics sells an after-market crankcase ventilation kit that is supposed to eliminate this leakage. I haven't tried it yet, but it seems plausible.

As Kapnkd mentions, exhaust leaks will make the cabin nasty in a hurry. They'll also set off your CO detector in a heartbeat. You do have a CO detector, don't you?

 

[Katie Jennings]

Ah... engine blowby (combustion fumes) is a different problem than gas fumes. You really want to track down and eliminate any fuel leaks.

If it's combustion fumes - one thing to check is that the little vacuum line from the manifold is intact. Vacuum lines aren't usually very tight, but they shouldn't leak. The A4 recycles some of it's blowby through the little rubber hose that recycles gases back to the intake, through the flame arrestor. It seems like this thing inherently leaks, especially if vacuum is low.

Indigo Electronics sells an after-market crankcase ventilation kit that is supposed to eliminate this leakage. I haven't tried it yet, but it seems plausible.

As Kapnkd mentions, exhaust leaks will make the cabin nasty in a hurry. They'll also set off your CO detector in a heartbeat. You do have a CO detector, don't you?

Yes we do - and it has gone off a few times, prompting us to turn on blower, open hatch, bring everyone above decks... as you say it would be good to nail this down before it gets cold and we spend more time down there.

 

[kapnkd]

Yes we do - and it has gone off a few times, prompting us to turn on blower, open hatch, bring everyone above decks... as you say it would be good to nail this down before it gets cold and we spend more time down there.

“Houston, we have a problem!”
...Definitely time to check out your exhaust system.

 

[Parrothead]

“Houston, we have a problem!”
...Definitely time to check out your exhaust system.

+1 on this. You have a problem and are using the blower to manage it rather than solving the problem. The interior of a properly maintained A4 powered boat has no smell including when the engine is running.

 

[ChrisS]

The A-4 in my boat has been both safe and reliable during my 15 years of ownership.

Two things:

- Get the Indigo kit to capture blow by. You’ll have no smell.

-Install a fume sniffing alarm. Mine has never alerted me of gas fumes, but twice when the hot exhaust section failed (in six year intervals) the alarm did let me know.

 

[Katie Jennings]

The A-4 in my boat has been both safe and reliable during my 15 years of ownership.

Two things:

- Get the Indigo kit to capture blow by. You’ll have no smell.

-Install a fume sniffing alarm. Mine has never alerted me of gas fumes, but twice when the hot exhaust section failed (in six year intervals) the alarm did let me know.

Can you say more about “the Indigo kit?” What search terms would I use and/or do you have a link? Thank you!!

 

[Katie Jennings]

“Houston, we have a problem!”
...Definitely time to check out your exhaust system.

I’m a sailor not an engine mechanic of any sort so … how hard is it to reach the exhaust system and is this doable by a newbie or should I call in the experts?

 

[Katie Jennings]

No, it’s not normal.

IF you have the old factory designed standpipe that was wrapped in asbestos as well as the cross piece coming from the engine - chances are the pipe has deteriorated (as ours did) and the only thing containing the fumes is the asbestos wrapping, which can/does “blow out” with exhaust pressures.

We repowered years ago and replaced our original standpipe with an Aqua Lift system which has been trouble free to date.

My E-32 manual has the specs for the standpipe (probably the same??) should you wish to build a new one ...and we’re happy to share if you need???

Yes please!

 

[tpcorrigan]

As stated above If you boat smells like and old model A ford then I believe that it is the exhaust pipe and riser that is probably causing it. We had the same issues a few years ago and being fairly handy we actually followed the plans for a exhaust riser in the E27/29 manual on this website and built our own. in removing the the old one it was incredibly rusted and only the rapping was holding it together. It fell apart in our hands. You can have a shop do the work or as stated above there are numerous other risers available. Once our pipes and riser were replaced boat started to smell like roses (well maybe a 45year old boat). please make sure you have a gas and CO detector. Happy sailing _/)