Bdaniel808
New member
Here is what we have 1984 Sundance with a 260 merc and alpha one drive we think is running hot, we were out tubing all day and filled up with fuel and ate dinner, went back out and noticed we were running on the verge of going into the red. Pulled boat that night and put new impeller pump in it assuming we had found some zebra muscles inside the pick up screen and not knowing how long it had been in there the impeller that is.
So new water pump in out drive, at the dock still ran up to the red so new circulating pump was then put on assuming wasn’t circulating very well. So new impeller pump and water pump.
I was told while changing the water pump to check the flow coming in from raw pump and that I should see 3-4 inches of water column out of the the tube at idle or just a fuzz above idle. I did not see anything near that maybe an inch and that was at best.
So I ran the boat for about half hour at dock with mechanical gauge showing near or just starting to touch the red at 2000-3000 rpm but never climbing higher on that gauge I had with me a infer red temp gun....... here is what I found with that....
At high rpm at the dock in neutral per the temp gun, the temp sender was reading right around 170-180 degrees the whole front of the intake was similar as well as the back of it, the middle however on both sides was (the middle being front to back where the carb sits) was close to 300 at times, I am assuming maybe there is exhaust port recircing some of the exhaust...... but purely best guess not sure not that..... front of heads were around 200 and top of thermostat was 190 ish, exhaust manifold on top of the elbows were 205 range at lower rpm but would cool more when higher rpm but never reall cool enough to touch.
I also noted that if I took off the coolant tubes at the bottom of the exhaust manifolds there wasn’t a full stream of water coming out of them about half of the tube at best....
OH forgot to mention back flushed the oil cooler and not much came backwards out of it used a wash cloth to catch stuff.
So my theory is this I believe have an issue between new water pump in lower half of lower unit and the stern of the boat.... is there a chance that some blockage higher up in the outdrive???? Is that why I am not getting the 3-4 inches of water column out of supply line??? One last fun fact when I took off the hose coming thru the stern to the oil cooler which is close to the water line at the dock water barely ran in was like you see in the cartoons where it shoots across the boat..... but again may have been at water line just assume since some was coming in should have been gushing......
Thanks in advance and if I left something else please let me know...
So new water pump in out drive, at the dock still ran up to the red so new circulating pump was then put on assuming wasn’t circulating very well. So new impeller pump and water pump.
I was told while changing the water pump to check the flow coming in from raw pump and that I should see 3-4 inches of water column out of the the tube at idle or just a fuzz above idle. I did not see anything near that maybe an inch and that was at best.
So I ran the boat for about half hour at dock with mechanical gauge showing near or just starting to touch the red at 2000-3000 rpm but never climbing higher on that gauge I had with me a infer red temp gun....... here is what I found with that....
At high rpm at the dock in neutral per the temp gun, the temp sender was reading right around 170-180 degrees the whole front of the intake was similar as well as the back of it, the middle however on both sides was (the middle being front to back where the carb sits) was close to 300 at times, I am assuming maybe there is exhaust port recircing some of the exhaust...... but purely best guess not sure not that..... front of heads were around 200 and top of thermostat was 190 ish, exhaust manifold on top of the elbows were 205 range at lower rpm but would cool more when higher rpm but never reall cool enough to touch.
I also noted that if I took off the coolant tubes at the bottom of the exhaust manifolds there wasn’t a full stream of water coming out of them about half of the tube at best....
OH forgot to mention back flushed the oil cooler and not much came backwards out of it used a wash cloth to catch stuff.
So my theory is this I believe have an issue between new water pump in lower half of lower unit and the stern of the boat.... is there a chance that some blockage higher up in the outdrive???? Is that why I am not getting the 3-4 inches of water column out of supply line??? One last fun fact when I took off the hose coming thru the stern to the oil cooler which is close to the water line at the dock water barely ran in was like you see in the cartoons where it shoots across the boat..... but again may have been at water line just assume since some was coming in should have been gushing......
Thanks in advance and if I left something else please let me know...