Mercruiser Help!!! Not turning over!!!

Bt Doctur

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Aug 29, 2004
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the left side ,front to back are 2,4,6,8. the right side front to back are 1,3,5,7
clean or rusty looking water? Could still be salvageable . remove the manifold hoses and the block drains. drain everything first.
Dry the plugs/ replace the plugs and fire the motor as soon as possible to dry it out.you can run it for about a minute or two. let cool and fog the motor until it stalls.
this can be done without water.
To test the block, remove the spark plugs again, remove the large hose from the therm housing .the hose that runs from the circ pump to the therm housing. using a hose , fill the large hose until it comes out the therm housing.Watch the hose to see if the water level drops or wate begins to exit a spark plug hole.

pm`ing a cell
 
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becdea

Seaman Apprentice
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Aug 30, 2014
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In Michigan...clean water. I hooked it up with the muffs today to get her to start. When the old starter was on then figured it was the starter. Only that one plug had water in it. Not exactly sure which # it is I think#6
 

Bt Doctur

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only 1 cylinder may just be the manifold or the riser has a small rust hole allowing water into that cylinder only. The 2 inner most cylinder on the center rise usually get water in them first from a riser/elbow problem
 

becdea

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Ok, I hooked the muffs up anf pulled the plugs. Water shot out of the 2nd one on the right if you're looking at the engine from inside the boat.
 

Bt Doctur

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so you hooked up the muffs, turned the water on , cranked the motor and water came out of the 2nd hole on the right as you face the motor? that is #3 cylinder
But that way is still not a valid test. remove the hoses from the manifolds and drain them. Remove the large hose at the therm housing and fill it with water from a hose. If the level dosent stay constant, the block is cracked. If no water comes out a plug hole and the level is constant using the manifold hose connected at the therm , remove it and fill with garden hose to see if water comes out of a cylinder. Yes= manifold/ riser damaged.
call me
 

becdea

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I tested all the compression. It all tested fine. I put the plugs in and put the muffs on an turned on the hose. An she started right up. Ran her 4 times for 15 -20 mins tonight with no problems.
 

Bt Doctur

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All right then, run it for 20 minutes, let it sit overnight, in the morning pull the plugs and spin the motor over. Betting you`ll see water pop out a plug hole .
Only 1 cylinder, I`m betting on a hole/crack in the roof of the riser dumping water into the cylinder thru the exaust valve.
If you just try to start the motor without pulling the plugs I can bet you`ll damage the flywheel ring gear or bust the bendix gear on the starter.
 

becdea

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Man, I hope not. When the weather clears up I will try what you suggested.
 

becdea

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So do you think if I drop her in the water this is just going to happen again? I was hoping it was a case of hydrolock..
 

Bt Doctur

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If you have run the motor and have a leak in the riser it will find its way into a cylinder and cause hydro-lock. usually in most cases where only 1 cylinder gets wet its a hole in the riser allowing water to leak into that cylinder
#6 and #8 in the log style and 2,4 or 3,5 in the center rise manifolds
 

NHGuy

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May 21, 2009
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Yes it is hydrolock. It's possible that it's from the exhaust. An easy cheaper-than-a-motor repair. And you can't go boating til you fix the cause. If you do you, risk ruining the engine.
Reread post #28, he's giving you the key. Do that next or you are throwing out the test sequence.
 

becdea

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Aug 30, 2014
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Ok so I did pull the spark plugs. When I did the 1st time water drained out of #4 just a little (if your standing in the boat looking toward the back) (even #s are on the left 2,4,6,8 odd #s on the right 1,3,5,7 correct?) nothing else came out. Then with all plugs pulled I then turned the key like I was starting it over with the muffs on and water came out of #3. I also checked compression in all cylinders. All cylinders checked out in between the 130 to 150 range. I went and put new spark plugs in her after all the water was out. An then she started up. I finished changing the oil and also ran the boat 4 more times with the muffs on. So I should take all the plugs off again and double check there is no more water in the cylinders?
 

becdea

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Is this something I can do myself do you think? And what exactly do I need if that is problem so I can start looking/ price?
 

ENSIGN

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You must pressure test the block and manifolds Stop guessing
 

becdea

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Wouldn't it have gone back to hydrolock again if I put new plugs in and the wires back on the last few times I started her up with the muffs running?
 

Bt Doctur

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Your guessing and not listening. the manifolds can be removed and tested using a hose, once off the motor you can test the motor by filling up the block thru the large hose on the thermostat,Fill it to the top of the hose and see if the level drops or if water exists a cylinder.
 

becdea

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Myself and my family owe a long overdue Thank You to Bt Doctur. (I thought it had posted but now looking I realized it did not) A simple Thank you to Bt Doctur is not even enough. He took time out of his busy life to help a total stranger in order to get him and his family back on the water. You were extremely knowledgeable and extremely patient walking me through everything that need to be done. You are truly amazing and my family and I are very grateful for you! Thank You a Million Times
 
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