Still Overheating..Im at a loss here now..

[pbuzz3323]

2003 searay..5.0 MPI, 260 Hp engine...S/N..0m624941..I changed the Impeller..The thermostat..The water circulating pump and its still getting hot. My smartcraft gauge reads from 0.0 to .3 for water pressure..This is occuring in driveway on water muffs but I dont believe thats the problem because its never happened the first 4 years. When I start it..it runs fine then temp goes up. The thing is when its just idling is when I seem to have the problem..when I bring the RPMs up the temp will drop back down..I figure Id post one more time before I take her in..What else can I check???? I believe this is beyond my abilities now.

 

[Wotknot]

Re: Still Overheating..Im at a loss here now..

What kind of shape was the impeller that you changed in? All intact but just wore down?............missing pieces?........totally obliterated?

 

[Don S]

Re: Still Overheating..Im at a loss here now..

Is the impeller on an engine driven pump, or is it an Alpha drive with the pump in the drive?

 

[pbuzz3323]

Re: Still Overheating..Im at a loss here now..

The impeller was actually not too bad..no broken pieces..Im wondering if it was even bad now or if its just something else. The impeller is the brass seawater pump with a Bravo 3 outdrive.....Is it Possible it just needs more water than the muffs?

 

[pbuzz3323]

Re: Still Overheating..Im at a loss here now..

Is there anything in the outdrive..Other than the pickup?

 

[Fireman431]

Re: Still Overheating..Im at a loss here now..

I'm not an expert on cooling systems, but they're a bit different than your auto as they don't usually have the closed cooling system. Does yours? The higher the RPM, the more fresh (outside) water flowing through. Check engine water pump or a restriction in the heat exchanger, if equipped. Were there any pieces missing from the old impeller that could be caught in your system? How was the water flow through the exhaust? Troubleshooting hi temps can be a hassle.

 

[Don S]

Re: Still Overheating..Im at a loss here now..

Put it in the water and see what it does before you take it in. If your problem is because of using muffs with low water pressure you may be wasting money having a good system tested.
You won't even have to take it off the trailer, just set it in the water. Since it does it on muffs, load has nothing to do with the problem.

 

[chiefalen]

Re: Still Overheating..Im at a loss here now..

How is the water flow at the outdrive?If no flow, risers should come off and check for rust and obstruction.Might be the flapper came loose.

 

[nailem]

Re: Still Overheating..Im at a loss here now..

im no expert but i read a guy had a problem with the water inlet being plugged. not sure what the technical term is bit the little ports that the muffs cover, remove them and check to see if there is any debris clogging the inlet.

 

[thundercat 9]

Re: Still Overheating..Im at a loss here now..

I just put my 350 back in my boat and ran it to make sure everything was working OK. I could not find my muffs so I took a rectangular section out of a 45 gallon plastic barrel and filled it with water. I lowered my out drive into it and started the motor. I watched as my temp gauge went up to around 190 degrees and then fall back to around 100. 10 minutes later I started the motor and the temp gauge took about 5 minutes to start to move off of the 100 degree mark, then it went to about 160 then fell back to 100 (not a consistent or smooth transition) I did notice that you have to rev the motor up to flow more water. I think my problem is there is air pockets in the motors water jacket,and when the temp sender is not in water(only air) it doesn't work.

All that being said, your symptoms sound alot like mine, I just think that the motor has to be revving around 2500-3500 rpm for enough water to be
circulated through the block.