Grey foamy substance out of propeller exhaust

BuilderFL

BuilderFL

Junior Member
Lots of grey foamy substance along with water is coming out of my propeller exhaust.
Had a failed water pump and motor overheated getting back to the marina. I replaced the water pump and the head gaskets and now the motor runs very rough and dies in idle. Compression checked on all cylinders between 108 – 115 psi. 1988 Mercury 200hp.
Any idea of what this could be?
Thanks!
 
drop the lower unit and see if you have an oily film on teh water pump housing, sounds like the lower crank seal is gone
 
if at the prop its like CB said! OMC needs to be cleaned up of carbon to fix, do a decarb and use carbon guard in the gas from time to time! It's a OMC issue. Also for giggles look at the lower unit oil, if its low its leaking out, if its milky your leaking in, if clean its the unburned oil from above.

Good Luck!
 
I use the west marine 2 cycle oil, premix. Woke up early to work on the boat and its been raining hard.
 
Found the culprit; oil seals below water pump base were not installed correctly when I replaced the water pump. Thanks guys!
 
I was using the wrong O ring at the base of the water pump and it did not go all the way in. Well, I replaced it and it's doing the same thing. Could it be the Sea Foam?
Joe, whats the OMC?
And there is no oil from the lower seal.
 
builder, you said you replaced the head gskts after the overheat episode, were they blown and water was getting in the cyl or where you just being proactive?
 
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In my opinion there are two ways to get that much oil. Lower unit is leaking ( view lower unit oil for water intrusion and then pressure test it to verify fix). or your exhaust manifold is purging all the oil/ carbon that had built up in it. I asked about the oil being used as I have found significant oil purging from the exhaust after overheating a engine if the oil has a decarb / cleaning additive. And the oil you show is more grayish than rainbow stained indicating he oil has already then burnt. I agee with Phat, Pull the spark plugs to verify no water intrusion in clyinders after head gaskets install (will also purge exhaust). If not and the lower unit pressure checks go run it and see if it cleans up.
 
Guy, no water in the plugs and compression is all within 5 psi (110-115) and I am almost certain that it had more to do with the Sea Foam and purging old carbon than anything else. All the grey stuff is gone but I cant get her to idle correctly. Since Im back on the road my mechanic is picking up the boat tomorrow and will take a look at it. I will post results as soon as I hear back from him.
Thanks for your input.
 
:news:$580 later, the old trusty 1988 Merc 200 is back to running sweet.:time:
The whole grey stuff was the sea foam cleaning whatever was inside the motor, so the lesson here is, when trouble shooting, do one thing at a time only. It was all carbs...they replaced the gasket kits, valve kits (not sure what this is) and a new pump diaphragm. Parts was $142.10 including $25 for picking up the boat and $405 for 4.5 labor hours.
What do you guys think about the bill amount? Fair or over the top?
As always, my thanks for all your input and support and I guess I should stick to my architecture and try to lay off the mechanic in me. Not! My favorite uncle was a car mechanic, was working with him since I was 14 till I went off to college and I really enjoy it, plus I've made a significant investment in tools. Just wish I had more time to work on the boat, the old truck, the spare motor...but I need a plan to get rid of the bills that just keep coming in every month before I can stop working (the jobs that actually pay).
Fishing tomorrow at 6am. If I'm lucky you'll get pictures :haha:
 
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