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MonkeySeaII

Drive issue

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2 hours ago, Randall Harbert said:

Wingnut, Is this common for small blocks too? Does a 377 MAG put a lot of heat through the drive too? Just curious...Thanks!

Yes. unless you have captains call through hull exhaust. Most IO's push the exhaust through the center of the prop. The super heated exhaust (up to 1800 degrees) must be quenched to something under 220 before it reaches the rubber exhaust hoses and boat transom itself. Water jacketed exhaust manifolds help, then all spent cooling water gets mixed with the exhaust stream as it exits the risers. This warm water adds little to no heat to the lower gear case as it spends it's life partially immersed in sea water. The upper case however only gets splash cooling at speed. My feeling is that engine pushing less than 500 HP do not need a drive shower. I much prefer a Bravo to get up to normal operating temperature quickly, and stay there. Drive showers on high output applications however are not only good insurance, but a necessity IMHO. If you are burning up gear oil in a Bravo, something internal is a  miss.  W

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49 minutes ago, Wingnut said:

Yes. unless you have captains call through hull exhaust. Most IO's push the exhaust through the center of the prop. The super heated exhaust (up to 1800 degrees) must be quenched to something under 220 before it reaches the rubber exhaust hoses and boat transom itself. Water jacketed exhaust manifolds help, then all spent cooling water gets mixed with the exhaust stream as it exits the risers. This warm water adds little to no heat to the lower gear case as it spends it's life partially immersed in sea water. The upper case however only gets splash cooling at speed. My feeling is that engine pushing less than 500 HP do not need a drive shower. I much prefer a Bravo to get up to normal operating temperature quickly, and stay there. Drive showers on high output applications however are not only good insurance, but a necessity IMHO. If you are burning up gear oil in a Bravo, something internal is a  miss.  W

Great information! Thanks for your advice!!!

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