Blown top end - advice needed

[christian_wlcp]

needing help.

mercruiser 350 mag mpi

temp rose up to approximately 220 (no warning beep went off), noticed it before it got any higher. immediately shut it off.

long story short, i think the top end is blown. pulled the spark plugs and waters shooting out.

any advice on taking my next step. help much appreciated.

 

[gcboat]

Re: Blown top end - advice needed

First thing I'd do would be to pull the plugs and crank the water out of the cylinders. Then throw in as much kerosene, diesel fuel - anything except gas to keep the cylinders from rusting up.
Check and see which side has the water and then pull off that head. Obviously if both sides are waterlogged then pull them both. Might just get lucky and warped the heads a bit which will require some machining - and new head gaskets of course.
Nothing venture - nothing gained. But get that water out fast !!!

 

[wca_tim]

Re: Blown top end - advice needed

more detail would be helpful... as in what vconditions were, what you were doing, was it running and working right and happen all of a sudden or is this the first time out, etc, etc, etc....

it is possible that all that happened is you lost your exhaust manifolds... no matter what, get the water out... wd40 sucks as a lubricand but is very good at dissolving water. marvels mystery oil is decent as well... I would find some of the threads from bond-o or don s regarding hydrolocked motors and follow the instructions to get things dry. note that it would e a good idea to remove the exhaust manifolds first... if that's the source of water, you won'thave any more flowing in... we'll cross our fingers for you...

 

[christian_wlcp]

Re: Blown top end - advice needed

wca_tim

owned the boat since 02.. bought brand new. has approximately 1000 hrs on it. i was having issues w the thermostat last summer and was not regulating the temp correctly. banged on it and it started working again. put probably 30 or so hrs on it since april and was working fine. when this occured we had been wakeboarding for a couple hrs and on my way back in had it almost floored. it started to slow down so i let off then it fixed got back on it for not more than a couple seconds as i was checking everything to make sure it was okay and noticed the temp had gotten to almost 220. immediately shut it off. lifted the engine hatch and heard a sizzling sound and smelt a kind of burning smell.

thats as about detailed as i got. let me know if u have anymore advice.
thanks

 

[TilliamWe]

Re: Blown top end - advice needed

You burned up the exhaust shutters, and maybe melted the interal parts of the exhaust hose. That was most of your smeell right there.
You probably ruined your exhaust manifolds/riser and their gaskets. You probably did not crack a head or blow a head gasket, though. It takes a little more than "almost 220" to do that to a SBC.