Another Big Twin Observation....

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FrankR
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Re: Another Big Twin Observation....

Postby FrankR » Sun Aug 12, 2018 9:09 pm

amuller wrote:Thank you very much for this discussion. I have not seen the issue of flammable vapor from crankcase drainage recovery previously addressed.

I'm thinking of the activated carbon canisters used to recover crankcase fumes and gas tank vapors on cars.


Interesting idea. But those have to be purged, don't they?

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chris
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Re: Another Big Twin Observation....

Postby chris » Mon Aug 13, 2018 3:36 pm

Is this flammable vapor not the same flammable vapor that already exists inside the fuel tank above the fuel?
I'm intrigued by this project, makes me want to do the same, but I'm not understanding how this vapor is any different than vapor being put out the standard way, or what's already in the tank and carb. I'm just not seeing a safety issue by running this back to the tank.
1955 10hp, 25hp, 1957 18hp Johnsons. 1958 35hp, 1972 50hp Evinrudes. Among others...

Chris_P
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Re: Another Big Twin Observation....

Postby Chris_P » Mon Aug 13, 2018 4:32 pm

chris wrote:Is this flammable vapor not the same flammable vapor that already exists inside the fuel tank above the fuel?
I'm intrigued by this project, makes me want to do the same, but I'm not understanding how this vapor is any different than vapor being put out the standard way, or what's already in the tank and carb. I'm just not seeing a safety issue by running this back to the tank.


Pretty much the same, but not quite. It has been atomized in the carb through the venturi, when it goes into the combustion chamber. By the time it is back through the drain system, there is not much vapour left. Remember, its getting dumped right beneath the hot fiery hell of the exhaust chamber!

Chris_P
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Re: Another Big Twin Observation....

Postby Chris_P » Mon Aug 13, 2018 4:35 pm

Why would the air line that pressurizes the pressure tank not need a vapour sepearator on it?

Just trying to figure this out.....

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VinTin
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Re: Another Big Twin Observation....

Postby VinTin » Mon Aug 13, 2018 10:05 pm

Chris_P wrote:Why would the air line that pressurizes the pressure tank not need a vapour sepearator on it?

Just trying to figure this out.....


I think you are on to something.

I don't think my system needs a vapour separator. At first I liked it because I could see the rate at which the condensate dripped. Then it etched up and I couldn't see. Right now I have that motor resting as I run other motors. I've put in new transom wood and will not be installing the separator again. The air vent on the tank does have to be sealed or vapor escapes from the fuel tank. I was hoping not to have to seal the fuel tank vent hoping the liquid would drop out of the separator and the vapor would pass on to the air box. I'm running a 15 gallon fuel tank and the 1957 35hp Johnson has a fuel pump.

Just venting the fuel tank up to the air box would be smarter.

Bill McNamara
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Re: Another Big Twin Observation....today' efforts

Postby Bill McNamara » Mon Aug 13, 2018 10:46 pm

Installed a couple of new exhaust housing gaskets and ran the engine on the hose today.
Unfortunately the same result as original observations, with a sort of turquoise fluid in the collection bottle again.
So, where to look next???

Some facts
Engine ran for about 20 min on fast idle.
Purged the lines for a few minutes to clear out Sunday's fluid.
I DID see some vapor in the bottle today.
Pulled the plugs right after shut-down, one had the slightest trace of dampness barely evident.
I only had the one "muff" so could not make a fluid volume comparison simultaneously.
Took some pics of fluids collected on Sunday and today for comparison. Love the one on far right of cooling water ejected from exhaust spout!

The fun continues......suggestions welcome.

Bill.
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bobw
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Re: Another Big Twin Observation....

Postby bobw » Mon Aug 13, 2018 11:18 pm

Bill,
In your previous post, I thought you were onto something when you found the loose exhaust cover screws and what looked to be water intrusion at the bottom of the exhaust cover/exhaust chamber. The inner exhaust baffle plate looked good, right?. I couldn't see any sign of perforation in the plate.

Assume you used gasket sealer when installing new exhaust gaskets?

Applied gasket sealer to exhaust cover bolts?

Any sign of water seepage around the outside of the cylinder head gasket?

Unfortunately, might have to pull powerhead and check lower crank seal.

Those are some great looking motors. Hope you can track this down.
Bob
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1954 Johnson CD-11
1958 Johnson QD-19
1972 Evinrude 25202

Jerry Ahrens
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Re: Another Big Twin Observation....

Postby Jerry Ahrens » Tue Aug 14, 2018 6:35 am

Question: Since you are catching unburned oil here, and dumping it back in to the fuel tank, do you not end up with too much oil in the fuel? Does this stuff need to be filtered before doing so? You are still loosing some unburned hydrocarbons overboard via the exhaust system anyway.
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FrankR
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Re: Another Big Twin Observation....

Postby FrankR » Tue Aug 14, 2018 7:15 am

Just by the amount of water in the original collection, I would have sworn you had a pin hole in the exhaust baffle. But I guess not. If that much water gets past the lower seal, I am amazed. I know it gets enough to ruin the engine, but never would have thought it would be that much. I guess we all are on a learning curve here.

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VinTin
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Re: Another Big Twin Observation....

Postby VinTin » Tue Aug 14, 2018 7:37 am

In three years I didn't have a problem with too much oil in the fuel. In theory the original mix ratio could contain a little less oil. I did sometimes mix at 28/1 or 32/1 trying to compensate some of the added condensate oil added. The viscosity of the collected condensate looks to be the same as the original fuel mix. My system has a filter in the tank pickup and one in the fuel pump. Yes some unburned hydrocarbons from the input charge passing through the motor pushing out the burnt charge do end up overboard just like they do if no condensate is being collected. We see litter along our highways but there are stiff penalties if you are caught adding to it. There is a surprising amount of condensate collected. On my 1974 40hp 'Jungle motor' the condensate and vapor are directed back into the intake cover of the other cylinder eliminating the dumping of it overboard. It is run through a screen in the condensate reed valve system. This likely results in the poorer idle these motors are know for as the cool slow running motor gets it's intake charge further enriched with oil and the heavier fuel tailings. Enriched right at the time enrichment is not needed which as least when running it back to the tank most of the enriched collected is burnt at higher RPM's.

As a side note my 1974 Jungle motor routes each cylinder's condensate and vapor to the other cylinder intake cover as I mentioned earlier. These condensate reed valves allow for each cylinders' condensate to be collected separately, which I have done. The lower cylinder collect more condensate when it was routed to two seperate collection tanks.

Here is a photo and link to a Suzuki vapor separator and recovery assembly that contains a float and valve system that routes vapor into the incoming air stream and uses a fuel pump to pump the fuel/oil condensate back into the fuel system before the carburetor. This is self contained under the cowling and is similar to system OMC also used. https://www.ebay.com/itm/1987-2003-Suzu ... 0005.m1851

Suzuki vapor recovery assembly.jpg
Suzuki vapor recovery assembly.jpg (69.56 KiB) Viewed 21 times


1974 40hp Jungle motor:


005 Intake covers Crankcase drain lines.JPG
005 Intake covers Crankcase drain lines.JPG (750.65 KiB) Viewed 18 times


Photo showing seperate routing of the condensate from the collection reed plate cover:

40hp 1974 Johnson Crankcase drain reed cover 002.JPG
40hp 1974 Johnson Crankcase drain reed cover 002.JPG (888.78 KiB) Viewed 18 times
40hp 1974 Johnson Crankcase drain reed cover 004.JPG
40hp 1974 Johnson Crankcase drain reed cover 004.JPG (839.77 KiB) Viewed 18 times
Last edited by VinTin on Tue Aug 14, 2018 7:54 am, edited 1 time in total.


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