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AQ125 raw water problems

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XxStarXx

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So I got a AQ125a in a 21' trophy the boat was having a cooling issue where the motor would run hot after awhile (200-210ish) I parked the boat and was going to fix it later well that was 3 years ago I have finally found the time to pull it out and fix it so I got it running great after dealing with old fuel issues and what not..... I tore down completely the fresh water and raw water cooling systems on the boat I replaced all the gaskets, took off the exhaust manifold rodded out the water passages with some wielding wire looking for blockages then hooked a garden hose up to the tube on the bottom side of the manifold and checked water flow through the water ports into the elbow and everything flowed great out of all the ports and the flow looked pretty even as well, I tore down the heat exchanger and pulled out the element gave it a couple baths in muratic acid and water then pressured washed the inside and out then cleaned the housing it looked pretty clean inside. I pulled off the raw water pump cleaned it all up and replaced the impeller the raw water pump housing appears to be good ( not sure what a bad one would look like) I also replaced the thermostat with a new 180 deg one. I cleaned the fresh water reservoir tank as it had a little bit of gelling in it. I also replaced the cap on the top of the radiator as the gasket was worn and cracked... I pretty much did everything I could of think of to do as it needed it.... Well I got everything back together and ran the boat in the driveway and noticed it didn't seem to be pumping enough water on the raw water side of things out the drive port. I took off the cap on top of the raw water heat exchanger and the sea strainer to look to see if there was water, I noticed the water level was to the top of the heat exchanger element but below the the hose port of the tube coming from the impeller pump. When I run the engine with the raw water cap off it will flow water up to the top of the neck of the raw water filler but not really overflow like I'm assuming it should do? If I cover where the raw water cap and sea strainer goes with my hand or put the cap on the water level will go back down to just over the heat exchanger element and blow the the tube coming from the impeller pump and appears not to be pumping water take my hand off it will fill up and flow some water but not near enough... I suspect I'm sucking up air somewhere but not sure where or how to find it I'm thinking somewhere near the impeller or the impeller itself but not sure any tricks, tip, or suggestions would be most apreacaited or if there is something I'm doing wrong or missing or something I should be checking... I'm not really good with I/O's this is the first on I have owned

Thanks for the input
 
280 outdrive?
If so, you do know there are 2 water pick up points on the lower unit right?
Bout a 1/2 inch hole near the bottom directly in front and the usual spot i assume your hooking the ear muffs to.
 
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It's a 270 drive but basically the same thing 2 port.... One on either side on the lower unit on the inboard side.... And yes using ear muffs
 
This is where im talking about.
 

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That's kinda what I was suspecting I pulled the impeller pump off again after my post and checked the rotation and key way on the impeller it was correct but when I put it back together again I did coat the o-rings on the two tubes at the impeller pump with permatex as the connections are a bit pitted as you said.....this has been a saltwater only boat for its whole life (1984) I'll try to fire it up tomorrow and see what happens... With any luck I'll be setting crab pots and reeling in some salmon this weekend lol

I really apreacaite all the help and suggestions thanks guys
 
XxStarXx said:
My drive doesn't have that hole on it
Click to expand...
The hole that Pat mentions for the 280 lower unit, is a water drain port...... your 270 will also have one.


Unless I missed it.......... I have not seen the "water neck" fitting mentioned.
The water neck fitting is a wear item, and along with the special beaded gasket, it must be routinely replaced.


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One tiny breach in the suction hose system, and your seawater pump will not function.


.
 
The only reason i mentioned that hole is.
If your running it on muffs you will suck air if that hole is not plugged.
Took me about 2 hours to figure out i did not have a real air leak, just needed to plug that hole then all was fine.
 
I'll look again for the hole I might of missed it the drive was close to the ground And couldn't get get my head all the way under there or feel it with my fingers I'll lift it this time lol

when you mention "water neck" which are you referring to? The one on the back of the fresh water expansion tank that houses the thermostat or the plastic one that sits on top of the heat exchanger? In any case they both have new gaskets and o-rings installed with a light coat of permatex the plastic appears to be in good shape and not cracked as far as I can tell
 
Ricardo posted a picture above in post #11
It will be located on the outdrive between the upper and lower bellows where the yellow circle is.
Mine was very corroded also but not leaking. Here is also a pic of my old one.
 

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On my boat, the brass ends of the raw water pump were too worn out. Open it again and look for grooves. When working properly and in the water, with lid off the strainer, water should pour out pretty quickly
 
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