did i just lose a cylinder
 

Hey guys....was just out in the boat and when I came on plane I started losing rpm in one of my engines.....it ran about 800 rpm below the other engine at 4600 rpm..I immediatly pulled back and shut down...also had a ticking noise and the engine was running rough before I shut her down. Any one have any ideas.....did I lose a cylinder? What does that mean? Total rebuild?

Call your mechanic.... OR
 

My first thought would be to check oil and see if there is any water in it.

If not, check compression examining each plug.

If compression is within limits and plugs appear fine, likely ignition problem.

Likely with the ticking sound it is serious. While not likely, it could even be something as simple as a rocker arm malfunction!

You might want to be following the discussion on OSO questions about repowering

I just noticed you have outboards... same things , you just get to the part about questions about repowering faster...

he has OB's, no oil to check, I would start pulling plugs and see what they look like, dont panic yet, it could be anything

Four Strokes
 

Aren't 300's 4 strokes?

Pete, you are right, it very well could be something simple, but at 3800 rpm and ticking chances are it is not simple.

Having said that, I had a 150 which started a high speed ticking which sounding like a valve lifter (it was an OMC 2 stroker, so no lifters). I shut down immediately.

Ended up being a $3.00 part on the prop shaft that had broken and was allowing too much travel on the gears.

Just pulled the plugs and all were good aside from the lowest port plug. The head was smashed against the main plug body with a lot of cut metal on the head. Any thoughts?.......I assume its not good news

hung a ring. do a compression test for ****s and giggles.

2 or 4 strokes?

fixx
 

anytime you see a smashed sparkplug on a 2stroke its not good..was the plug loose???? that may have been the ticking noise you herd,when that cylinder ran lein it makes everything in that cylinder red hot and that is why the plug came loose and the electroad was smashed from the alunimum fron the side of the piston and the rings flying at it..just do a compression check on that cylinder with the throttle all the way open,,try not to turn over the engine any more then you have to because that cylinder may be saved,the less you turn it ove the less scratches..

The engines are 2 cycle pro max. Thanks a lot for the help guys.....I guess my first step will be compression testing tomorrow.

Yup...what he said. Sounds like you leaned out a piston. Lets hope the cylinder wall is not scarred.

The engines are 3.0l? Bottom port is the number 6 cylinder, on the 3.0 liters, that is the problem hole. Mine sucked water through the o ring on that cylinder and trashed that hole.