Please help

[sebas54]

Hi, I have a 1987 4.3 mercruiser that wont start. When I turn the key it tries to start and then it bangs. Turn the key rev bang. Please help this is my first boat and I don't kow much about boats. Thank you

 

[Gary H NC]

Re: Please help

Bang as in starter or engine stopping dead?
Pull the spark plugs and try to turn it over.Check for signs of water in the cylinders and oil.
Have all electrical connections to the battery and starter including grounds been cleaned?

 

[sebas54]

Re: Please help

Hi, thanks for the reply. The bang is from the engine stopping. I haven't pulled te plugs yet but the oil looks normal (black). What do you mean by turning the engine over once I pull the plugs? Sorry for th e stupid questions. Can there still be water in the engine? All the electrical components are good and clean. thanks

 

[Don S]

Re: Please help

It may not be water. Could be a broken rod or a broken valve and the piston hitting the valve.
Look at the spark plugs, one of them could be beat up.

 

[thrasher]

Re: Please help

As both Don and Gary have suggested, remove all 6 spark plugs and look at them. If all 6 look normal try turning the ignition key and see if the engine turns over smoothly (it will not start as the spark plugs are missing).
If there was water in a cylinder it will come out the spark plug hole. If the engine still goes bang, then as Don suggested, it's probably something more serious and will probably require removing the engine from the boat to diagnose.

Gary

 

[sebas54]

Re: Please help

Hi. I just came back from the boat and yes there is some water in the engine. I couldn't remove the spark plugs because there is no room. I stuck my finger in the filler cap and there was signs of water contamination. Please help. What could have caused water into my engine. How do I fix this. Thank's, I appreciate all replies.

 

[180shabah]

Re: Please help

Cracked block, cracked head/s, bad head gasket/s. bad manifold/riser, bad gasket between them.

 

[180shabah]

Re: Please help

If there is water in a cylinder, you need to get it out NOW. If you have to dissassemble seats or something else, do it. The longer you leave water in there, the worse it will be.

 

[bomar76]

Re: Please help

I couldn't remove the spark plugs because there is no room. QUOTE]


Pull the exhaust manifolds....then you can get to the plugs.

 

[Bondo]

Re: Please help

I couldn't remove the spark plugs because there is no room.

Ayuh,......... You're not trying Hard enough,.......
Get the right Wrenches,+ Remove whatever's in the Way........

If you Can't pull the Sparkplugs,....... Nothing We say here is going to Help anything.........
That being the case,........ Call a Boat Repair Shop.............

I stuck my finger in the filler cap and there was signs of water contamination.

On the inside of the Oil filler cap,..??..??.....
That's Probably just normal Condensation.............

 

[sebas54]

Re: Please help

Thanks for all the info. I just finished pulling the risers/maifold and plugs. Bond-o, you were right about the condesation under the cap and under the valve cover. I did see some water or moister on all three of the plus on the other side of the motor. No water came out. The rise/man and gaskets all seemed to be in good shape. I am not sure as to what's next. Also it didn't bang when trying to start; water shot of one side. Please help.

 

[Haut Medoc]

Re: Please help

Thanks for all the info. I just finished pulling the risers/maifold and plugs. Bond-o, you were right about the condesation under the cap and under the valve cover. I did see some water or moister on all three of the plus on the other side of the motor. No water came out. The rise/man and gaskets all seemed to be in good shape. I am not sure as to what's next. Also it didn't bang when trying to start; water shot of one side. Please help.

That is because it had enough time to seep past the rings into the oil pan.....
The water is sitting at the bottom of the pan & won't emulsify until the engine runs a bit.....