My big Mercury over heated

[Captian-Dan]

Hi all,<br />Last weekend my 1988 200 hp Mer over heated.<br />I took it to my friends repair shop and he advised 2 pistons were not getting fuel via the carb. i/e no premix was making it thur the carb. Now it looks like an overhaul is required as 2 of the 6 pistons are shot. Does anyone know why the premix was not making it the pistions? I premix my gas 50:1 and do not use the oil injection as it never had oil injection when I bought the boat and motor last summer.<br /><br />

 

[JB]

Re: My big Mercury over heated

You have several carburetors on that engine, Capt. Dan. It seems one of them, the one that feeds those two cylinders, got plugged up or failed in some other way that cut off fuel to those two.<br /><br />Good luck.<br /><br />Red sky at night. . .<br />JB

 

[Captian-Dan]

Re: My big Mercury over heated

Thanks JB. This is a comman occurence with multi carb? And should I go for a total rebuild of the engine or should I just replace those two pistions and then have the carbs rebuilt?<br /><br />Thanks for your advise!

 

[hondon]

Re: My big Mercury over heated

You won't know what damage has been done until you at least pull the heads to inspect the cylinders. Crank damage is also possible.Redoing only two holes oversize is acceptable.

 

[Trent]

Re: My big Mercury over heated

Have your carbs done.. Sounds like one was running lean. Was it "lean sneezing" also at idle??

 

[Mike M2]

Re: My big Mercury over heated

Wiseco makes a great piston for a fraction of factory cost. You are gonna have to totally dismantle the powerhead, and check connecting rod bearings(next to go after pistons). Hopefully they are ok, as Merc isn't releasing any rods till next year due to tool refitting(least thats what they are telling me).

 

[Captian-Dan]

Re: My big Mercury over heated

Thanks everyone for the info. The forum is <br />awesome! Have a great thanksgiving..

 

[rkoenigsma]

Re: My big Mercury over heated

you should rebuild it. it would be worth it. u know it will run good then

 

[Lanier8]

Re: My big Mercury over heated

I understand what everybady is saying but<br />has anybody done a compression test?<br />Rex A. Hubble

 

[Fouled Plug]

Re: My big Mercury over heated

If two pistons are trashed, why a compression test?

 

[Rex]

Re: My big Mercury over heated

let's just say you did one and it check 150 psi. how do you know that they are trash?<br />The compression test is easy and cheap.<br />All I was saying was to make sure.<br />Rex A.