6.2 Bravo III Overheating

[OrlandoBoating]

I have a 2004 Sea Ray Sundeck 270 with a Mercruiser 6.2 MX Bravo III that will overheat after warm up. After leaving the dock at coasting speed (no wake zone) the temperature gauge will rise very quickly to about 200-210 degrees after about 4-5 minutes. I have determined that this is an actual temp not an sensor/electrical false reading. My first thought was a thermostat sticking as the temperature rose so quickly it seemed to have no water flow at all. Let me know your thoughts. Thanks

 

[mjfink]

Re: 6.2 Bravo III Overheating

Here are my guesses:

1. If you haven't changed the water pump recently, that would be the first thing I'd check
2. Exhaust manifolds/risers (again, if you haven't done them recently)
3. Thermostat

The first thing I would check is the water pump; they will fail ever few years and need the impeller changed; if you haven't done that recently, I'd put my money on the impeller has totally failed.

 

[TilliamWe]

Re: 6.2 Bravo III Overheating

Yep, first thing to check in a boat when it overheats is the impeller in the raw water pump. Especially if you have NO water flow at all. Because the way the thermostat sits in the housing of a Mercruiser (and probably a Volvo Penta also) water ALWAYS flows out the exhaust. ALWAYS.

 

[HT32BSX115]

Re: 6.2 Bravo III Overheating

Let also add that since it appears that you have a completely failed impeller,

You'll need to remove the oil/pwr steering heat exchanger to clear out all the pieces of that impeller that have been jammed in there and will obstruct water flow when you do replace it.