Mercruiser 8.1 Hydrolock?

I'm not sure you are going to be able to pull the starter. You may have to tap the starter housing to jog the drive into retracting. Since you probably also won't be able to get near it with a hammer, you can use a metal rod/bar to contact the starter housing and then hit the free end with a hammer (went through a winter semester with an old chevy with a bad Bendix drive).
Success! You are spot on, Henry. Tapped the starter with power on, and it retracted. It was done though. Drained all the water from the muffler and used the pump to evacuate all water from the engine. Switched the starter from the other motor and the motor turned. Ran the starter till all the moisture was out. Put the plugs back in and the belt back on. Put the drain plug back in. Took awhile to get it started but it finally caught and ran. Ran it for minutes and checked for steam at the cap: none. Checked the oil: no water in the oil. Ran it for 30 more minutes at high idle. So far so good.
Thanks to all the folks that chimed in. So much solid knowledge.
 
Sounds great!! drain the oil anyway refill and take her for a long ride, And maybe change the oil one more time
 
Sounds great!! drain the oil anyway refill and take her for a long ride, And maybe change the oil one more time
Yup, change oil, filter, and plugs! Then run it. I may not want to flush the engines again. It may be better just to use the boat...
 
You have to run it hot (not at the dock. Running at speed) for as long as possible and change the oil after. You really need to get any water out of the oil. Changes alone won’t do it.
 
Sounds great!! drain the oil anyway refill and take her for a long ride, And maybe change the oil one more time
You have to run it hot (not at the dock. Running at speed) for as long as possible and change the oil after. You really need to get any water out of the oil. Changes alone won’t do it.

Couldn't agree with this more. Run it.
 
Couldn't agree with this more. Run it.
I did! Ran it fast for a while today. Stopped after 5 minutes on plane to check on the oil. It was not milky, but was a little lighter than I expected. Took off the cap and saw no moisture. The oil pressure was a little lower than the other engine. I am hoping that the lower oil pressure is due to a little bit of water emulsified in the oil.
I got back on plane for another 30 minutes and it ran strong (amazing that an 8-ton pleasure boat can do 30 mph). Then I tied up at the dock and changed the oil immediately. The oil showed no milk.
I'll probably take a another fast spin and change it again in the next week, hoping to see more even oil pressures across both engines.
Once again, thanks for the quick and solid advice, folks. This site is fantastic.
What a roller coaster, going from moments of asking myself why am I tortured with loving boating so much, to the joy of seeing the engine fire up and rumble. Time for a cocktail...
 
Update: Yesterday's goal was to change the oil once more. The engine turned over fine, but it took longer for the engine to start than usual. I hit the on button, waited a few seconds after the beep, then pressed start. The engine turned but didn't fire after 2-3 seconds (the starter did not sound labored), so I turned the engine off and repeated. Second time it fired.
Once started, it ran solid and sounded normal. Ran it hard in the bay, with no engine alert errors. The oil pressure is the same on both engines. After running hard and docking, I changed the oil again. The oil didn't show any signs of water. I'm a little bothered about the long start.
I wonder if I need to open the exhaust risers and check/scrape the turbulator plates. If water was in the exhaust it likely fouled them, which may add pressure on the exhaust side. I should have looked for rust after the start, but did not.
Anything else I need to do?
 
Not uncommon for mercruiser mpi engines to not fire right up immediately. All mine have done it over the years. Think it has something to do with fuel pressure. Someone else may have more insight.
 
Wow amazing post. Who would have thought after that ordeal the starter went bad at the same time. Unreal.
 
I recall reading that the 8.1s won't allow the engine to fire until a revolution or two. Thought it was meant to safeguard against hydrolock by not subjecting the engine to more torque than the electric starter can produce. Then again I might have read this in a dream too...o_O
 
Definitely a priceless story. Wonder what this scenario would have cost if Tacoma290 would have just call in a Merc mechanic and told them to just fix it? Thousands I bet.
Wonderful thread!
 
Need help on how to protect the block.
Came back from a day trip on Sunday. Engines ran solid. Shut them down. Came back the next day to flush with these:
Fig%200456%20Flush%20Pro.jpg

While the flush was going, the port engine would not start. Stopped the flush. Smartcraft said Port MAP input Hi. Thought the sensor was bad and that battery was the issue and used the emergency start (in hindsight perhaps not the best move), but the port engine would not turn over. Called it a night.
Now I am thinking hydrolock, and that the pressure of the water during flush may have overwhelmed an exhaust gasket, or the gasket failed when the engine was shut down. And that the MAP sensor was correct. Will pull plugs and check oil today. Have read to add Marvel mystery oil to the 'wet' cyclinder(s) assuming that there is water in there to prevent rust.
Questions: How would this oil be added to the cylinder since it is in a bottle? Is there some other spray in oil to be used?

I have a question. Did you flush the engines without them running? Just wondering, because I have a flush system similar to the perko and always flush with running. Once i'm done flushing I shut off the engine then turn off the water within 5-10 seconds.
 
I have a question. Did you flush the engines without them running? Just wondering, because I have a flush system similar to the perko and always flush with running. Once i'm done flushing I shut off the engine then turn off the water within 5-10 seconds.
I flushed them running. But the timing for stopping the flush is critical. To stop the flush, normally one turns off the engines, then stops the flush water. I recall that Mercruiser says to not run the flush without engines for more than 15 seconds. Your 10 seconds are a much better number and leave a safety factor.
My marina is 10 minutes from home and 10 minutes from work, so I now simply run the engines once a week, and am avoiding the need to flush.
 
I flushed them running. But the timing for stopping the flush is critical. To stop the flush, normally one turns off the engines, then stops the flush water. I recall that Mercruiser says to not run the flush without engines for more than 15 seconds. Your 10 seconds are a much better number and leave a safety factor.
My marina is 10 minutes from home and 10 minutes from work, so I now simply run the engines once a week, and am avoiding the need to flush.
Thanks. I have 2 safety features. I plumbed my flush right before the strainer. When I turn on the water it comes out the seacock grate. Once I start the engine it pulls in the fresh water. When I shut it down the water comes out the bottom. Hard to explain, but I'll never have that problem. Look at my thread..

http://www.clubsearay.com/index.php?threads/new-flush-system-installed.87193/#post-984386
 

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