'06 496 mag bravo 3 over heating at higher speed

[jsea558]

Hi everyone, I've developed a new issue this season. I boat in saltwater. First trip out ran boat up on plane was at normal temp, 170-ish. Pushed throttle to about 3400 rpm (about 24-25 knots). Temp gauge started to slowly rise to 200+. And alarm went off. Backed down to displacement speed and temp. went back to normal. Repeated same senario same outcome. Pulled up to nearest beach, shutdown for couple of hours. Headed back to marina. Couldn't duplicate problem. It ran normal all the way back??? Next day ran again and it would only really heat up over 20 knots. Maybe bravo-itis, or seawater pump? Pump was rebuilt last season. I did find shells in aft side of oil cooler. Any help would be appreciated. Thanks

 

[Jimmy Buoy]

Probably the water inlet hose on the "outside" part of the outdrive restricting the flow. Lots of posts on the subject if you do a search. The best solution seems to be installing a separate water pickup in the engine room to supply water directly to the engine. The raw water pump is NOT in the drive for Bravo models, so bypassing the usual water supply from the drive is ok.

 

[Jimmy Buoy]

Here's one post…

http://clubsearay.com/showthread.ph...I-transom-clogs)?highlight=bravo+water+supply

 

[Jeremygavin]

Another thing to check, I never had an over heating problem but I did start to run on the warm side on both my engines last year also my raw water water pressure was high as well. This spring I back washed the entire raw water side of the cooling system with barnacle buster. A lot of stuff came out of the water system, barnacles, seaweed, etc.
Now I am running normal psi in the water system and engines are running just under 160deg at a 3400 cruise.

 

[jsea558]

Thanks guys, I was thinking about bypassing the transom housing hose. There is a pad, in the bilge right near the seawater pump, to put a scoop and seacock. Probably add a strainer as well. Back flushing is a good call as well. Thanks again

 

[SAshton]

Also if you leave in water you need to split the outdrive case every couple years and clean the barnacles and antifoul the inside. You'll be surprised how much build up will be there and especially if it's never been done.


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[b_arrington]

My father inlaw just had a problem with very similar symptoms. Ran fine under 20 mph, temp shot up to 200+ over 20 mph. Ended up being water hoses restricted from growth. After cleaning them out the engine is running fine at normal temps over the normal speed range.