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post #14 of Old 12-18-2012
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Re: Full throttle needed to start Yanmar 2GM20F

Originally Posted by 73Morgan View Post
Ok, I am listening, does this apply to fresh water cooled engines?
Yes.. in either case the RW is pumped through the engine (RWC) or a heat exchanger(FWC) and then is injected into the exhaust system to keep the noise level down and to cool the exhaust run out to the transom.

The water is driven out of the exhaust system by the running engine's exhuast gases. If the engine never catches, the rotating RWpump will fill the muffler, eventually possibly backing up into the exhaust manifold where it will find an open exhaust valve and run back into that cylinder. This can cause 'hydrolocking', where the engine won't turn because it can't compress the liquid pocket in the cylinder.

I'm still leaning toward a faulty injector, certainly it's the top candidate for the 'hammer' sound while running.


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