Another Big Twin Observation....

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FrankR
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Re: Another Big Twin Observation....

Postby FrankR » Fri Aug 10, 2018 9:29 am

A little digging on e-bay finds there was a RJE-18, a RJE-18E, and a RJE-18C. With that, I don't know what the specific changes were.

https://www.ebay.com/itm/Parts-Catalog- ... %7Ciid%3A1

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VinTin
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Re: Another Big Twin Observation....

Postby VinTin » Fri Aug 10, 2018 9:34 am

As has been mentioned, it is either an exhaust side plate baffle or the lower crank seal.

As a side note and not related to the water in recovered fuel issue you are having: The fact that both high speed needles are each 1/4 turn out in no way equates to each high speed adjustment being optimal. Close maybe. But maybe not.

I feel that a recovery system that does not also collect and burn the fuel/air mix that goes through the crankcase drain reed system is incomplete and presents a fire hazard. This vapor is extremely flammable and when the pooled liquid is expelled there is quite a bit of vapor exhausted. You should easily be able to feel it coming out of the vent holes in your bottles at mid and high speeds. This needs to be routed back up and into the air box to be combusted. So far I seem to be the only one taking this vapor into account. In an aluminum boat this vapor will condensate on the hull and leave a very oily residue in the bilge area after enough run time.

Attached are some photos of my system. I agree with what was stated that a clear tank shows the water intrusion. Feeding back to my one tank results in my not seeing water if it is there. I have collected in a clear tank so I do know I'm not getting water. It is something I should do once a year or so in case something changes.


Crankcase drain recovery system w seperator 002.JPG
Crankcase drain recovery system w seperator 002.JPG (455.54 KiB) Viewed 198 times


Crankcase drain recovery system w seperator 001.JPG
Crankcase drain recovery system w seperator 001.JPG (713.26 KiB) Viewed 198 times


Vapor fed back to the air box via the slightly enlarged fogging hole. The barb is held into the air box with a piece of fuel line pushed onto the barb.
fuel recovery 004.JPG
fuel recovery 004.JPG (237.31 KiB) Viewed 198 times

Chris_P
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Re: Another Big Twin Observation....

Postby Chris_P » Fri Aug 10, 2018 3:52 pm

VinTin,

Run a down pipe that extends submerged into the fuel mix in your tank from the barb for your recovered fuel back to tank.

You didn't remove the reeds behind the cover plate did you?

You should not be getting a vapour cloud like that.

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VinTin
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Re: Another Big Twin Observation....

Postby VinTin » Fri Aug 10, 2018 6:56 pm

Chris_P wrote:VinTin,

Run a down pipe that extends submerged into the fuel mix in your tank from the barb for your recovered fuel back to tank.

You didn't remove the reeds behind the cover plate did you?

You should not be getting a vapour cloud like that.


I did not remove the reeds behind the cover. Doing so would result in a back and forth pumping action as crankcase pressure goes negative and positive. With no reeds it would be a very busy little operation going on behind the reed valve cover as the two crankcase pressure/vacuum cycles are 180° out of phase.

We should be getting a vapor cloud. It is that way by design.

It is vapor pressure in the crankcase that pushes out the condensate after it pools. After all condensate is gone positive crankcase pressure on every downstroke releases some vapor.

When it is dark outside run a motor in a water tank and a flashlight will easily show the vapor coming from the recovery tank. At 1,000rpm the vapor plume is about a foot in length. Looks like fog. Highly flammable. I know of two other people who have crankcase drain recovery systems on 1950's 35hp OMC's and all three of us have seen the oily residue the vapor mix leaves behind on Feather Craft aluminum hulls as it condensates there.

I stand strong in my conviction that this phenomenon is being overlooked by many and is a hazard. This vapor plume is the same as the vapor that goes into the cylinder each stroke and is ignited by the spark plug.

If the vapor was not to be expected there would be no need for vapor separators on more recently designed OMC motors.

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

Postby Bill McNamara » Sat Aug 11, 2018 7:50 am

Vin Tin,
Thanks so much for your in-depth post and safety alerts, much appreciated.
I have considered venting the bottle(s) overboard, as a small bilge pump through-hull already exists on the port side near the stern. I had also thought about directing vapors back into the breather, but thought it might cause mixture setting problems, apparently not.
So far I have not witnessed any vapor either visually or odor wise, but it's got to be there.I haven't had the occasion to check at night yet.

I did check the clear bottle this morning, and the water seems is settling out alright, leaving about 2" of clear gas-oil mix on top, so there doesn't seem to be any question that water intrusion is the culprit.

It's only this Port engine that happens to be set at at 1/4 turns out for the HS jet.

We did resist taking the Twins out yesterday, but did use another boat with a RDE-19, that I also modified this Spring. After going through 2 tanks of fuel, I recovered about 2 cups of clear (thankfully) mix from my collection jug.
Although my systems are very basic, I like the concept and hope to continue refining the systems.
Thanks again for your inputs.

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VinTin
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Re: Another Big Twin Observation....

Postby VinTin » Sat Aug 11, 2018 8:25 am

Thanks for the kind words Bill. Almost 100% of the time I'm just regurgitating what I've read from others here in our club.

I like the idea of burning the vapor in the motor via the air box method but it may also have safety concerns. These systems get more and more complicated up to and including float bowls and fuel pumps that pump the recovered liquid back into the fuel system at the carb. Look for vapor separators on ebay for some interesting and complicated systems. I've looked at these and have though some of them may be usable on our classic motors but have never made the step. Suzuki's are seen quite a bit on ebay.

Dan

fleetwin
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Re: Another Big Twin Observation....

Postby fleetwin » Sun Aug 12, 2018 7:21 am

OK, I understand what is going on now....Thanks
Sorry to hear the water is settling out on the port engine....
And yes, everyone is correct, you need to find the problem to avoid destroying the powerhead....
Hopefully, someone can determine if your engine has the lousy lower seal set up....
I'm assuming you did not remove the powerheads on these engines...
Such a beautiful rig, so sorry you have to disturb the beautiful paint job...
I'm sure this has been addressed, but am assuming there is no water in your fuel system....

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

Postby Bill McNamara » Sun Aug 12, 2018 8:04 am

fleetwin, The fuel supply system checks out OK, and motor runs nicely which is a bit of an oddity.The water is not seemingly getting in through the carb.
I'm glad that we caught the problem early so I didn't mess up the engine.

Bill.

amuller
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Re: Another Big Twin Observation....

Postby amuller » Sun Aug 12, 2018 8:39 pm

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.

Chris_P
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Re: Another Big Twin Observation....

Postby Chris_P » Sun Aug 12, 2018 8:49 pm

I always run a down tube into the fuel tank from the barb. Never had an issue, and I have done a few of these conversions. In my little brain, the vapour is mixed and filtered through the fuel tank mixture and dissipates.


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