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57 mercursier very loud metal clanking noise

kenkee1

New member
"I am a new comer and hope I c

"I am a new comer and hope I can get pointed in the right direction. I have a 5.7 mercrusier that I just had rebuilt just over a year ago(burnt piston) and dont have but maybe 10 hours on it. I have had it out 4 times this year however the last trip I had problems. We took maybe a 1/2 hour ride with no problems at all. We shut it down swam a little and when I started it up it did not sound normal. It shut off on me after putting into gear. I got it started again and put it into gear and just idled for a few. The motor just did not sound right. (studdering,missing, and knocking a little)I shut it down opened the engine compartment up and started it again and heard a very loud clanking noise. It was not a continious noise but like a one time noise but very loud. My first thought is no not again. I had it towed home and started looking into it. I tried to start it and it turns over okay but now it will not start at all. I have not heard that loud noise again. I pulled the cap and the rotor turns. I pulled the plugs and turned it over and no sign of water. checked the oil no sign of water there either. My next move is a compression check. I was reading a earlier post and found a similer problem and it ended up being the upper unit spun a bearing and cracked the case. If that is my problem would that cause the engine not to start. I checked and I am getting gas to the carb and spark at the coil. Any suggestions will be greatly appreciated. thanks"
 
"spark at the coil"

"spark at the coil"

Is the sark getting to the plugs? Coil wire bad?

Are you getting any noise at the OD when it cranks?
 
"Sorry, yes I have spark at th

"Sorry, yes I have spark at the plugs. I really do not hear any noise now while cranking. It sounds like it wants to crank but just is not catching."
 
Do you mean it just won't

Do you mean it just won't start? Is the choke closing when cold and opening when hot?
 
I am trying to get it started

I am trying to get it started again so I can try and hear what is wrong and where that loud clanking noise maybe coming from. Since I have owned the boat(4 years)I pump the throttle 3 times and it fires right up. Even If I am down a cylinder shouldn't it still crank up?
 
With the engine off remove the

With the engine off remove the top cover of the OD and look at the gears for breakage.
 
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