Overheating. Almost done saga.

ColoSR said:
Have you considered adding a thru hull intake to make a dual pickup (thru hull + leg)? I have a 1 1/4" thru hull on mine and it moves so much more water than the 3/4" transom fitting from the leg. There isn't anything I can do to overheat the engine when the thru hull is open.
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We have considered that many times, however, it seems a drastic solution. Something went wrong with the existing cooling system. To add a hole in the bottom may be more of a plan B than resolving the actual problem. So holding off on that for now.
Like what if we drill a hole then find out she still heats up. Need to find the cause not the solution.
 
This may be odd. My dad had a 79 Galaxy BR with a closed cooling V-P.

constantly overheated. He bought it from the dealer new as last seasons model at the end of the year.

10
years he fought overheating.

They dinged a prop and had to limp several miles civilization.

The only shop that was still open sold him a prop. Owner came out. They start talking. Guy says. Try draining the antifreeze out of the block and fill it with water.

Never overheated again.
 
WinkBuilt said:
This may be odd. My dad had a 79 Galaxy BR with a closed cooling V-P.

constantly overheated. He bought it from the dealer new as last seasons model at the end of the year.

10
years he fought overheating.

They dinged a prop and had to limp several miles civilization.

The only shop that was still open sold him a prop. Owner came out. They start talking. Guy says. Try draining the antifreeze out of the block and fill it with water.

Never overheated again.
Click to expand...
Raw water cooled. Probably the simplest cooling system since the Model T.
 
Due to the rapid temperature rise under load, it seems like you have a hole in the suction line that is drawing in air or the suction line is kinked or collapsing under load. Are you sure that the water hose that is connected to the outdrive is tight? That connection would be underwater when you are idling at the dock, but might be out of the water and can pull in air once you are on plane.
 
My thoughts... Some mentioned...

1. Confirm correct riser gasket. They have about 2 or 3 different styles.
2. Confirm hose isn't collapsing.
3. Did you say you replaced the small power steering HXer? Looks like a cylinder on the intake line?
4. Hoses on correctly at pump? Intake vs. Engine supply?
5. Infrared temp gun on the risers to confirm temp.
6. Remove thermostats as a test... Still overheat?
 
Espos4 said:
As far as I know, there are no hoses inside a bravo outdrive unit. The only water inlet hose goes from the bell housing to the transom. Water drawn up through the lower unit enters the vents and travels through a passageway from the lower unit, up into the upper unit and then into the hose.

Has the outdrive been split and has this passageway been inspected/cleaned? If so, when reinstalling, make sure the o-ring seal is good as well as the seal between the upper unit and bell hosing.

Both of these areas are under water when idle but are exposed to the air when you are cruising. Leaking seals will suck in air when cruising and cause an overheat.
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Great suggestion. I had the same thing occur on a volvo/omc drive. Oring had failed between the cases.
 
When I fixed bravoitis on my old boat I rebuilt the drive at the same time. after 15 years that outdrive passage was 50% full of barnacles. could definitely affect cooling
efficiency. Worth a check.
 
techmitch said:
Run a clear hose from the inner transom fitting to the pump and take a look while this occurs.
Click to expand...

YES!! ^^^^

Pirate, it’s way past time to stop throwing money and faith at this and do some DIY diagnostics.

1) Remove the incoming water hose from the thermostat housing and hold it a few inches below that point. When running you should have a 2-3” plume of water.

2) Splice in a 6” piece of clear hose, run on plane with a friend looking for ANY bubbles going past.

3) I think that your block may be partially clogged with rust scale, sand or both. This is tricky to clear but can be done with some ingenuity.

Take a break from the mechanic for a while. His kid’s college fund isn’t your responsibility.

Get a manual and DIY. You have an old boat and apparently deepish pockets. A mechanic’s wet dream.

No boat I’ve ever owned has been laid up for more than a week.
 
Our overheating issue was clogged heat exchanger and clogged intake. Have you had her on the hard and run her with muffs on? Does she over heat on the hard? Our heat exchanger had hidden growth inside it even though we had done the risers.
 
I second a thru hull water pick up. I've seen this problem often and so far it always fixes the problem. The clear hose is a sure way to diagnose bubbles in the pick up water. The bucket is a good way to prove water flow but a thru hull water pick up is direct from the thru hull to the raw water pump.
 
Brite Idea said:
I second a thru hull water pick up. I've seen this problem often and so far it always fixes the problem. The clear hose is a sure way to diagnose bubbles in the pick up water. The bucket is a good way to prove water flow but a thru hull water pick up is direct from the thru hull to the raw water pump.
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This was suggested for my issue, but I'm glad I didn't do it. It would have been a waste of money for me. Mine is closed cooling, so this doesn't apply to Pirate Lady. Mine ended up being super simple. I had a coolant line going to the top of the exhaust manifold. If you have a riser it has to go to the riser. I'm sure it caused an air pocket the way I had it.
My point is that there is something wrong with his cooling system. Not the design. Backwards hose install, barnacles, rust causing a blockage etc.
 
I showed him all the suggestions. Leaning toward its sucking air somewhere in outdrive.
Got an outdrive specialist coming today, see what he says, may pull it off and let him take to his shop.
If he can’t come up with an exact cause/solution, then we going to take it to the big marina next door and let them deal with it. They are really good and had i known the pita this turned into i would have let them fix it 2 months ago.
I bet they can fix in a day but like i said above, very expensive. I think the smallest boat in that marina is 35’, 90% searays.
 
Pirate Lady said:
I showed him all the suggestions. Leaning toward its sucking air somewhere in outdrive.
Got an outdrive specialist coming today, see what he says, may pull it off and let him take to his shop.
If he can’t come up with an exact cause/solution, then we going to take it to the big marina next door and let them deal with it. They are really good and had i known the pita this turned into i would have let them fix it 2 months ago.
I bet they can fix in a day but like i said above, very expensive. I think the smallest boat in that marina is 35’, 90% searays.
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And by expensive I mean….
Last summer to short haul, replace impeller, flush outdrive, $620.
 
Does your vessel not have a heat exchanger in the engine bay (or two?) Mine were fully clogged - also tiny growth in the intakes in the legs so all the blockages together killed the impellers.
 
No. His is raw water cooled. Heat exchangers are only on closed cooling. Then again... There is an oil cooler and a power steering cooler that are heat exchangers if you're talking about them. They could definitely cause a problem.
 
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