Cooling system

R

Roy & Dixie

New member
There's always something. Yesterday while sea testing PermaTrim installation on 1999 F80 Yahama, I noticed no water flow from indicator that should have been been squirting a steady stream of water, and my interior gage had no reading. I checked the small hole to be sure it was not clogged. It was not. I even pulled the small hose off the outlet jet and, with the engine shut down, could blow back through the tube into the cooling system. The water jackets were cold. After I restarted the engine I could see water exiting ports on lower areas and water ran freely from the garden hose flush connection. The water jackets stayed cold and a little water flowed from the indicator line but ceased as I increased speed. I called the service dept manager, involved in the original sale. He said I should be ok, that silt was probably involved in stopping up the small tube. He said I would get over heat alarms long before any damage would be done. I cruised 2000-3600 rpm for 3-4 hr. Engine and water jackets remained normal temps.

I watched youtube instructions on installing a new impeller and feel this is a DIY project, but I want to eliminate any other possibilities to correct the flow problem first. Any thoughts??
 
If you don't know when the last time the impeller was changed, or can't find out, get in there and replace it -- and also check the water pump housing while at it of course. Depending on your usage and water conditions, this needs to be done every 2-3 yrs or more often for sure.
 
You might also try Salt-Away or a similar product. Worked on our big Suzuki 150s. Even no tell tale indication didn't lead to an overtemp alarm but I was still concerned. After several applications, it opened right up.

Charlie
 
Before you do that. cut a long , 2 ft, of downrigger wire ( or something similar) and run it thur the out let tub and see if their is a blockage.
 
Matt Gurnsey":kkqggplb said:
You can blow compressed air into the outlet with the engine running and that will often clear a clog.
Click to expand...

That worked for me too but eventually had to get rid of built up salt as it reclogged soon after. I'd turn the air pressure down with the regulator on your compressor though to 20-30 psi, wouldn't want to put 100+ on it! :cry

Charlie
 
I have used the compressed air and nylon trimmer hose to get blocks cleared up. I have also run 'Saltaway" thru a pressure system to fill the blocks.

The thermostats also need to be checked periodically, as well as the impeller replacement every 2 to 3 years as noted above.
 
Thanks for all the suggestions. I will begin today with wire through tubing, compressed air with engine running, and finally I will remove lower unit to access the impeller. I was told the impeller was replaced last spring but I do not know how much use, by whom, under what conditions since then. The boat had been used in combination salt and fresh water along Fla Gulf coast, then stored in an in/out service most of it's life. So I question if engine was flushed out each use. I will be using the boat in fresh water for 1-3 day trips, but will also get to ICW all along East coast, so info on Saltaway is good to know, both to clear up any old deposits and to maintain cooling system in the future.

This forum is a wealth of infomation. :thup
 
Does it have a pressure control valve?

Many replace it when the water pump replaced or every other water pump service.
They can clog open and best to replace instead of cleaning
 
Does it have a pressure control valve?

I did not see a pressure control valve yesterday. I removed the top of the thermonstat housing and thermostat appeared ok. I could not easily remove the thermostat, afraid I would damage or even destroy it unnecessarily.

I used 35psi air to blow back through the water jet tube and also through the hose fitting engine flush tube. These 2 tubes both go to a fitting on the lower level of the water jacket. I then cranked up with hose connected to "ear muff" and had good water flow out the indicator tube. I then also blew 35psi against the water flow, as suggested in earlier post. At idle the gage on dash reads @7psi and increases a lot if I place my finged over discharge hole to restrict the flow. So it looks like the impeller is good. Seller stated it had been replaced last summer.

I'm headed off to river for sea trial shortly.
 
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