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big block overheated

D

diamondl

New member
i have the exhaust off down to the y-pipe, and all looks well except the shutter valves are gone. i plan to replace these, all gaskets it took to get down here, and the impeller in the bravo 3 outdrive. it has only overheated once (the last time i was in the lake), and i came back with water in the cylinders. is the lack of shutter valves my problem or am i missing something?
diamondl
 
I suspect the water in the cylinders is a result of the overheat. Having said that, missing shutters will allow water in as well. I assume you got the water out right away, if not, do it now. Bravo drives do not have impellers in the drive, there is a water pump on the starboard side of the engine down low that is belt driven.
 
woodie
i have read several times in the last week that bravo drives don't have impellers, and the only reason i disagree is that i have replaced this one. you have to split the outdrive to do it. and strangely enough i think i saw the pump you are referring to just today. also sounds like you don't think i have found the problem, the only 2 things i can think of is some of my shutter valve parts pluging the exhaust/water outlet, or the heads. if i'm ever going to pull the heads it should be now, but i really don't want to if i don't need to.
thanks
diamondl
 
i have read several times in the last week that bravo drives don't have impellers, and the only reason i disagree is that i have replaced this one. you have to split the outdrive to do it.
Click to expand...

Ayuh,... If there's an impeller in yer drive,...

It Ain't a Bravo...
 
Yes, no impeller in a Bravo. If it's a Merc, you have an Alpha drive. If you suspect there are shutter parts missing and still in the exhaust, remove the drive and look through the exhaust bellows and into the cavity of the transom assembly as well as the exhaust section at the front of the drive when you pull it off; two likely places where shutter parts may end up as well as the exhaust passage inside the drive that is accessable when drive halves are apart. The older shutters were a single SS plate with a rubber/plastic edge and a shaft, the newer/replacements are dual plastic/rubber flaps, some have a plastic collar as well. The shutters are there to assist in preventing water from making it's way up the exhaust and into your engine due to swells, reversing, launching down ramp etc. You need to install new ones.
 
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