omc 3.0 won't start.. any ideas?

Don S

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Well Jim, the first thing you will need to do is get a service manual (click here for one option.<br />You may have ring problems, but to find out you will need to do at least a Compression Test to determine if you have compression enough to even start the engine.<br />You also need to see if you have spark to the plugs, no spark could indicate bad points, bad coil, burned wire or .........<br />Are you sure the plugs were covered with oil only or did they have water on them.<br />Your overheat problem may also have been a bad impeller, has it been replaced in the last few years?
 

Don S

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Re: omc 3.0 won't start.. any ideas?

What year engine do you have, and do you have the Cobra drive?
 

fatboyjim

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omc 3.0 won't start.. any ideas?

hi there.<br /><br />i'm a newbie on here and also in the world of mechanics so please go easy on me as i'm trying to learn by the seat of my pants at the mo (so to speak).<br /><br />i would normally get a mechanic to look at stuff for me but i cant find anyone who will look at an OMC engine and so here goes.<br /><br />my engine overheated and i had to be towed back to my berth as i couldn't get it to start after i had switched it off. a mate of mine who knows just slightly more than me found that the drive belt was very loose and suggested that this might have been responsible for not bringing water into the engine to cool. the engine turns over and so i don't think i've seized it - however i pulled the plugs out to give them a clean (this is the limit of my technical knowledge) and they are oily and wet. according to research i've done on engines in general - this could indicate that the piston rings have bust. <br /><br />can anyone who knows more tell me if i am looking in the right direction. would an overheat do this?<br /><br />another thing that might or might not be relevent is that the bilge pump was out and there was a lot of water in the engine bay area up to the starter motor which i have since manually pumped out with no major result.<br /><br />cheers for any help you can give me.<br /><br />jim
 

fatboyjim

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Re: omc 3.0 won't start.. any ideas?

thanks for your quick reply. the engine had a total rebuild just before i bought it earlier this year so i think there is a good chance that it might be quite new. the drive belt was very very loose and a little bit of research that i did led me to beleive that this was what would power the water intake. <br /><br />the plugs were covered in dirty oily looking water.. rather than actual oil. it looked like oil but it was wet rather than greasy.. if you catch me drift!<br /><br />jim
 

fatboyjim

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Re: omc 3.0 won't start.. any ideas?

yep i imagine so anyway - its a 1988 omc cobra.
 

Don S

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Re: omc 3.0 won't start.. any ideas?

On the Cobra drive, your raw water pump is on the drive behind the back cover and easy to replace. But if your belt was that loose, it would sure cause an overheat.<br />
the plugs were covered in dirty oily looking water.. rather than actual oil
What you may have been seeing is gas mixed with the oil, was there any rust??<br />While you were trying to start it, gas would be going into the cylinders, but with no spark the gas would not burn off and would then mix with the oil and be wet looking. Water would bead up if you put it on your hand, gas would soak in.<br />You might try cleaning and drying the plugs and see if you have spark.
 

fatboyjim

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Re: omc 3.0 won't start.. any ideas?

thanks for that. i think i'll be replacing the plugs anyhow as i managed to destroy 3 out of 4 of them when i removed them - they were in very tight..<br /><br />i'm not sure if it was rust or carbon although they were very grimey looking they wiped clean really easy. rust on the plugs would mean salt water was getting into the cylinders would it?
 
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