Gray foam(lots) from exhaust outlet 1957 Evinrude 10hp

[docscott]

Hi folks. We found a lot of gray oily foam with a gas smell running out of the exhaust port on a 1957 Evinrude 10hp. We had it out for a Spring checkup and trolled for 3 hours. It had almost no time at full throttle. We thought it was possibly missing like once every minute but it did not stall or even effect performance but we kinda thought it may have jolted A LITTLE each time it missed. Overall performance was great at low speeds and we did not make any speed adjustments. Ran very well at moderate /open speeds.
It had had a grease job, new plugs, new lube in lower housing ,fresh gas:oil mix 50:1, a tank test and a few speed adjustments while in the tank.
In the garage it dripped lots (1/4 Cup) of the gray foam. We laid it down and lots more came out and you could see it up in the exhaust port.

So what is that foam?
Is there a mechanical problem?
Will running it like that hurt it?
What’s causing this?
Do you have any solutions that would help us?

Your time and expertise is greatly appreciated.

Oh the motor hasn’t been tuned up in maybe 5 years and is only used for trolling 2 weeks a year every other year. I will talk with DB to get a checkup and really needed tune-up. It’s a gem of a motor and in excellent shape. Thank you ,Scott.

[crosbyman]

OIL MIX SHOULD BE 24/1 SOME RUN 16/1… NEVER 50/1

run the motor wot for a good run gray goo should dissipate

Joining AOMCI has priviledges 🙂

[frankr]

Gotta be one of the most often asked questions. Here’s a recent one:
viewtopic.php?f=2&t=11332&p=59873&hilit=emulsion#p59873

[bobw]

If you did a lot of low speed trolling it was probably just loading up with fuel – the foam is caused by unburned fuel/oil mix coming out the exhaust which is normal. It can also be thick if there is a lot of old carbon buildup in the cylinders and in the exhaust housing which leaches out with the unburned fuel. BTW, you should be running that motor at a 24:1 mix not 50:1. That vintage of motor also had issues with the wrist pins wearing out (actually the wrist pin holes in the pistons) and some folks even use 16:1 mix to help with that problem.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[chris-p]

Simply unburnt fuel/oil mix mixed into the spent cooling water. Very normal. Ensure your carb is set to optimal settings. We can help with that if need be. As stated, run her at 24:1 to ensure that your grandkids can use it after you!

Changing your oil may help. I don’t own shares in BRP, but find that the XD series of oils have little to no smell, and show very little sheen on the water. I run XD 30 in all of my older motors at the recommended ratios.

Do a decarbon as well with Seafoam or OMC Engine Tuner.

[vintin]

Some of the ‘gray foam’ is from the crankcase drain reed valve system.

[Author]

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