bobkatz

Is there a chance you had a wrong plug(spark) in it as in much hotter heat range? Also are you sure the block is OK? It seems a half a rod flopping around with 5 cylinders driving it could do a bit of block damage. Bad Deal!

Brad Zastrow

Fuel pump, pressure regulator, Fuel pressure too low. Injector dirty, Bad gas, Oil pump, head gasket are any of many issues
That is detonation. The other cylinders are also lean. Take it to a different mechanic. If you rebuild it will blow again unless you find the problem.

BUP

iTrader: (9)

fuel pressure and proper 2 stroke oiling is very important here. Also what Mike said looks like some water might have been entering. Also what does your spark plugs look like and what does the heads/ combustion chambers look like. Also what shape is your reed valves like and any missing ?

Wobble

I would say that it was an air leak, assuming that the fuel system checked out.

BUP

iTrader: (9)

forgot Merc's oil pump is not the greastest either also the check valve they get stuck especially from sitting long periods of time. Also rod bolt maybe came loose or had too much play. Check the crank out as well.

272bajadriver

iTrader: (1)

Very valid point. Something caused that rod to break in half. The bottom half of the rod was perfect still on the crank. Top half of the rod is the way u you see it on thr pic. Just trying to find a cause before I put new powerhead in. I was real upset to find out the injectors were good. Is it safe to rule out a part failure such as the rod breaking? Guys on here have definitely more knowledge than me and I appreciate all the responses.

Motors spin to 5800rpm I was going 65 at 5000 rpm and just trimmed the motors up a little. I was looking ahead so didnt pay attention to temperature to see if it overheated or not. I immediately heard a clunking so I came to an idle and shut the motor off immediately.

272bajadriver

iTrader: (1)

All replies have been great. I will address the oiling by removing the oil pump and just premix from now on that way I can eliminate that as a future possibility. As far as the spark plug on that cylinder the piston took it off along with the threads on the head for the spark plugs. The other plugs look good I'll see if I can get a pic downloaded

tpabayflyer

That sucks you had a failure but your motors sounded good when you left the island that day! That picture really shows a clean piston like it was steam cleaned so maybe a bit of water did get in there? I would say check all the wiring to verify that each injector is firing..... I also wonder if the piston pieces restricted travel at the top of the bore and caused the rod failure after the fact? Detonation would certainly cause that as well..... I just don't have any experience with outboards but I will ask my local marine guy what he thinks......

machloosy

I think the above response outlines the most likely reason for rod brakeage. I think it was a secondary result of the piston burning. Whether a piece blocked upward travel, or something else, I'd bet the rod broke after the fact so to speak. Also, if the crank hasn't been tested, don't assume it is good by just a visual inspection. The bearing obviously needs replacement, and I would think the crank needs a real good check out.

shaun1368

Sorry to hear the bad news......I lost my six cylinder a year ago..almost same conditions as you. At the time, I was using crap oil and believe that May have been the cause (although my mechanic and I never really found a definitive cause). Also had a gas smell in the oil reserve (is that a poss bad check valve...replaced that too). In the end, it was any one of many poss causes. Now, I just try to keep an eye on all gauges, use top brand oil and fresh gas with stabil...I'm also suspect of bad gas/ethanol phase change. Keep us in the loop on what u find