boat over heating

Gasman

Gasman

Member
May 30, 2015
80
Great Lakes
Boat Info
2001 29' sun dancer sold
2000 340 sundancer
Engines
Twin 5.0 mercruiser
7.1 v-drives
i have a 2001 290 with twin 5.0s.... just put boat in the water today.... went for a cruse starboard motor reached 200deg... so i turned it off....i read somewhere that the bravo 2 does not have impeller inside just the water pump on the motor is that true...... i read online it could be the t-stat or the impellers in the outdrive.... are there any checks i can make before having change the water pump changed... boat temp was fine in oct when i took it out of the water.... Note: over the winter I changed the starter,changed gear lube, both propellers, and had the outdrives greased...
 
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I think your mechanic not only knows best, but is right. Your impellers in the water pump are most likely shot. That could lead to the pump being shot from the high temp. That's what happened to me.

Mark
 
Still sounds like water pump impellers. I bet when they're pulled out, you'll see they're done. They need to be changed every 2 years.

Mark
 
Gasman said:
i have a 2001 290 with twin 5.0s.... just put boat in the water today.... went for a cruse starboard motor reached 200deg... so i turned it off....i read somewhere that the bravo 2 does not have impeller inside just the water pump on the motor is that true......
Click to expand...

You have a Sea Water Pump with either a hose coming from the outdrive or a sea water pickup and a Water Pump mounted on the engine. The sea water pump has an impeller that should be changed, you may also have a blockage if the impeller came apart you need to check for any pieces and flush if it came apart.

Facing the front of the engine the sea water pump should be mounted on the lower left side of the engine.

The water pump is mounted on the front of the engine if it's bad it will usually leak water through a weep hole.

Here's a link to an exploded view of the sea water pump may not be your engine serial engine.
http://www.marinepartsplus.com/cata...L_EFI_GM_305_V-8_1999-2001/809500+99/4856-170

http://www.marinepartsplus.com/cata...L_EFI_GM_305_V-8_1999-2001/809500+99/4856-150

Here's an exploded view of a closed cooling system showing the engine water pump.

http://www.marinepartsplus.com/cata...L_EFI_GM_305_V-8_1999-2001/809500+99/4856-160
 
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well i got good news.... i changed the water pumps today... the starboard side was totally shot all the impeller blades were gone... had to back wash the the motor to get all the plastic parts out of the motor and t-stat.... the other was in good condition but changed it anyway.... now the starboard side temp gauge is bouncing all over the place any where from 130 to 170... not overheating ..... the port side is staying at a constant 170.....
 
Did you remove the t-stat housing and look real good for pieces of rubber impeller stuck in there? Or, are you POSITIVE that you got ALL the pieces? In other words, could you completely reassemble the damaged impeller from the pieces you found?

Were you running the boat on a hose or in the water and for how long?
 
i didn't try and put all the pieces together but there was a lot of pieces i got out.... i ran it in the slip for about 10 min... then i went out for a short cruise...
 
The first thing that comes to mind is that the t-stat/plastic spacer is installed incorrectly. The second thing is there might still be a piece of impeller hiding in the t-stat housing. There might even be one in the fuel cooler (if the piece is big enough). The t-stat stuff is easy... the fuel cooler is a little more difficult in your boat as the cooler is mounted down low, by the PORT side engine mount. And, as "luck" would have it, you're having the issue with the starboard engine. In a 29' boat, with twin V-8's, it doesn't leave you a lot of room to get down there.

But I would check these things first, before doing anything more drastic.
 
Yep do what Dennis has stated the easiest is to start with the t-stat since your temp is fluctuating is most likely would be there if not it's the cooler look at an exploded view of your engines water flow pretty easy to follow the flow not many places for a piece to be stuck,

I would almost bet it's in the t-stat if it were the cooler I doubt the temp would be 130-170 it probably would lodge in there and over heat.

But it's a boat they never do what you expect or the easy fix.
 
i would verify the temp is actually fluctuating with a laser temp gun.....if it is actually fluctuating the tips others have provided are spot on....if the temp is not actually fluctuating but the gauge needle does fluctuate I would suspect either a faulty temp sender or the brass/copper grommet in the T'stat gasket is not making good contact between the t'stat housing and the engine.....the gauge could be faulty but that would be the last thing I would expect however the wiring connections for the gauge could be corroded or loose.....

cliff
 
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