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6.2 MPI W/94 hRS Bravo O/D raw water cooled overheating at higher rpm's

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Ewhitehead

New member
Running motor on muffs w/ no load will not overheat (175) however with boat in water on plane motor overheats (200 plus) back off plane temp. drops to (175). What I have done: New therm, New raw water pump, Pulled both heads did a valve job checked for cracks reinstalled with new gaskets, pulled risers looked inside could see no obstructions. All of this has seemed to help the problem ( will run longer on plane w/o overheating. But the engine will still overheat at higher rpm's. Anyone had this problem or have any idea how to correct this issue I would very much appreciate the input! Thanks
 
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Thanks for the come back: Brand new sea water pump installed seems to be putting out plenty of water, have checked engine temp. with heat gun which shows 200 plus temp.
 
Ewhitehead said:
new sea water pump installed seems to be putting out plenty of water
Click to expand...

It needs to be measured, not just eyeballed...good choice on the IR gun...make a note to measure your engines, when operating, after you get the overheat issue resolved...nothing like a solid baseline in your log book for when the next incident occurs...
 
When you say plenty of water flow, where is the flow you are seeing?

Is it at the incoming water hose to the thermostat housing?

On common problem from earlier bravo models is at the transom where the water hose (to the left of the ujoint bellows) attaches to the transom assembly and where the water hose (engine side of transom ) meet. The method of attachment is a very wierd PINCH/COMPRESSION fitting.

this fitting can reak havoc if not wide open.

Also when you say good water flow, water flow is not always a good thing if bubbles are present. Water should be almost void of bubbles.

At this point if all is normal, pull the thremostat and retest.


when an overheat condition exsists at high speeds it typically is a lack of water flow coming in or some times it is a issue with water flow out (restriction).

also could you report back with the year of your motor/serial nimber so a water flow diagram can be looked at.
 
kghost said:
When you say plenty of water flow, where is the flow you are seeing?

Is it at the incoming water hose to the thermostat housing?

On common problem from earlier bravo models is at the transom where the water hose (to the left of the ujoint bellows) attaches to the transom assembly and where the water hose (engine side of transom ) meet. The method of attachment is a very wierd PINCH/COMPRESSION fitting.

this fitting can reak havoc if not wide open.

Also when you say good water flow, water flow is not always a good thing if bubbles are present. Water should be almost void of bubbles.

At this point if all is normal, pull the thremostat and retest.


when an overheat condition exsists at high speeds it typically is a lack of water flow coming in or some times it is a issue with water flow out (restriction).

also could you report back with the year of your motor/serial nimber so a water flow diagram can be looked at.
Click to expand...

Here is the water connection on a 2009 bravo. This boat required a new transom assembly.

Photo340.jpg
 
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Get an IR temp gun and check the temp of the exhaust manifolds, If the pump is new and the water feed tube is not restricted and the exhaust manifolds are around 200 degrees and the risers are around 90 degrees, the manifolds are clogged and need to be replaced.

If you have smart craft gauges check the water pressure.
 
I was reviewing what I have for pdf manuals and i have one with the water circulation diagrams for a efi/bravo system.

The cool fuel module is inline on the output of the water pump (impeller) so have you checked to see if there may be a blockage in the module?

I seem to remember someone finding this before..............
 
Thanks for the help. i replaced both risers and then ran motor and checked with temp gun. Readings are right manifold on top 190 and left 210, Center top right riser 157 and left 137. I think I need to replace both manifolds. I also put clear hose on and water stream does seem too have very few bubbles. Do you think this is adviseable? Thanks
 
Docksidemarineservices said:
Get an IR temp gun and check the temp of the exhaust manifolds, If the pump is new and the water feed tube is not restricted and the exhaust manifolds are around 200 degrees and the risers are around 90 degrees, themanifolds are clogged and need to be replaced.

If you have smart craft gauges check the water pressure.
Click to expand...

When you get it all apart, make sure you clear the hose fitting on the bottom of the manifold.
 
I have replaced both manifolds,risers,therm,valve job, checked for obst. in coolers, hoses. and motor still will run hot under load above 2500 rpm. What I have done has helped but still have the problem just at a higher RPM.. Manifolds will run above 200 and risers about 180 under load. I think only thing left could be obst. in outdrive,bad outdrive hose or fitting through the transom. Am I on the right track? Any other ideas will be most appreciated.
 
Thanks to all who replied to this post. I finally solved the problem, either a obstruction in outdrive water passage or more likely in the water fitting going thru the transom. Would have had to pull the engine forward to replace this. Which was not a very good option. What I did was to take the 1 1/4 inlet hose off and adapt it to a water hose. After doing this engine ran cool. So i installed a 1 1/4 thru hull pk up and ran directly to the sea water pump. Now engine runs about 110 not the 200 plus it had been running under load. The outdrive does not seem to be overheating after I did this.
 
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