OMC 120 dies in the water

[omcguy]

The engine will start but when its in the water it wont idle. We took the exhaust manifold off and the head to check it out and there was standing water in the two middle cylinder. How is water getting in there? The exhaust manifold has a nasty crack in two places but would that effect water flow, besides the water leaking out of the manifold itself into the bilge area.

 

[Boatist]

Re: OMC 120 dies in the water

Omcguy<br />If the manifold is bad then water usually leaks back in thru the the exhaust valve but if cracked like from freezing can also get in to the intake valve. Before you put the head back on I would check the valves very close. Could be rusted leaking and burnt from leak. For Saltwater engines manifolds last 4 to 6 years. Was the crack due to water in manifold freezing durning winter or just from rust and corrosion?

 

[omcguy]

Re: OMC 120 dies in the water

the valves look good, just normal black color. I dont see any obvious damage to the head or head gasket. Just the standing water in 2 cylinders threw me off. Why wouldnt there be water in all cylinders? Is that why it runs on land then when it goes in the water it dies? Either the riser to manifold or just the manifold is bad. Just want to make sure before I go and buy a manifold for 300 bucks.

 

[Juancho]

Re: OMC 120 dies in the water

You have described a classic case of bad manifolds and risers. These are both very easy to replace yourself. Buy the parts slap em on and your engine should be good as new.

 

[Walleye King]

Re: OMC 120 dies in the water

I need to know what plugs go in this same motor!! I just got the boat and want to see if it fires okay, was told ran great but I would like to make sure! Plugs were pulled because he said he oiled the cyl in the fall and never put them back and misplaced them.

 

[omcguy]

Re: OMC 120 dies in the water

thanks juancho, we've narrowed it down to that after the replies and all the other posts. Its going to be hard to track down parts for this though. I've been raking the internet for days and found nothing. Amarket.com cant get them anymore and they said GOOD LUCK finding them. Anyone out there HELP!?