Grey foamy substance out of propeller exhaust
 

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!

Un-burned gas and oil in the exhaust.

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

find a diagram that shows the crank and the case halves, look at the very bottom, it has a seal carrier, just below the bottom bearing
item # 30 on this page http://www.butlermarineinc.com/fiche...r=0&fveh=50024

you may be able to drop the lower unit and inspect it with a light from the bottom end, spin the motor over while you have the lower off, you may be able to see crank case pressure bleeding by the seal

Thanks spare! I'll work on it tomorrow.

FLBuilder:

Do you use walmart/Penzoil TCW3 oil with decarb/cleaner additive by chance?

Kamikaze

sue bp, everybody else in florida is.

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!