Hey Guys and Gals: It's weird. My boat, all of a sudden overheated one day and I immediately thought it was the impeller. The impeller was O.K. So the previous owner came over and changed out the mucked up thermostat and we thought it was OK until it overheated again. Now I'm at a loss. I guess there is a blockage in the cooling system but where? The raw water intake is O.K. What characterizes this problem is that the water exiting the boat has so much force and noise that you'd think it was coming out of car wash nozzle. So I think the blockage (if there is one) is pretty close to the exhaust outlet. Anyone else have this problem? BTW my engine is the venerable Atomic 4 a.k.a "the Bomb." Anxiously awaiting your replies, Melody
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M
Mark Smit
Exhaust Elbow
Sounds like your exhaust elbow is clogged. I had the same problem, once replaced the overheating ended.
Sounds like your exhaust elbow is clogged. I had the same problem, once replaced the overheating ended.
Blockage
I would assume that the blockage is near the end of the exhaust line. Could something have gone up the tailpipe from that end? I shudder to think anything big enough to cause the high-pressure spray-out described here could have gone all the way through the system. Climb in and pull the hose off the exhaust thru-hull (with the thruhull safely above the waterline and preferably with the boat out of the water) and see what you find. I'm betting it's a stick or a crab or seaweed or something. JC
I would assume that the blockage is near the end of the exhaust line. Could something have gone up the tailpipe from that end? I shudder to think anything big enough to cause the high-pressure spray-out described here could have gone all the way through the system. Climb in and pull the hose off the exhaust thru-hull (with the thruhull safely above the waterline and preferably with the boat out of the water) and see what you find. I'm betting it's a stick or a crab or seaweed or something. JC
R
Rob Rich
Poor Melody! Try this first....
Hey Melody, Sorry you are still having cooling problems. I thought we had this licked with the last post. I would do two things. First, do a basic, techical troubleshoot and, if needed, use marsolve. The value of a serious troubleshoot cannot be underestimated. First, we need to look at the whole picture. Where does the water enter the boat? From that point, where does it go, and where does it exit? What I suggest is checking the flow at every point along the way. First, is water entering the through hull cleanly? Is there a blockage in the strainer? If not, is it coming out of the oberdorfer waterpump in sufficient quantity? If it is, how about the thermostat? If you remove it and run the engine, does it shoot out of the thermostat housing? If so, you will need to trace each point of the exhaust system, looking for the point at which the flow is reduced. If you find reduced flow, then at least you know that the problem lies upstream. Now, if you find the problem lies in the engine (water jacket)try a product called MARSOLVE. It is a marine deposit solvent that the military has used to remove accumulated marine deposits inside engines. You will need to circulate it with a drill pump, bit it is supposedly excellent at freeing up the water jacket on old A-4's. The independant results I have heard are very inspiring, though limited in number. If my engine weren't running so well, I'd use it myself. If the Marsolve doesn't help, you may actually need to take the head off and do a serious cleaning on the jacket. Scale can, unfortunately, be a real bitch. At the very least, you will spend several hundred bucks and have a real solid engine. You may as well replace the head gasket and check the valve train while the head is off. Lastly, please keep us posted on your results, as you did last time. Everytime I hear something like this I file it away as a tool for any problems I encounter with my boat. Best of Luck, Rob
Hey Melody, Sorry you are still having cooling problems. I thought we had this licked with the last post. I would do two things. First, do a basic, techical troubleshoot and, if needed, use marsolve. The value of a serious troubleshoot cannot be underestimated. First, we need to look at the whole picture. Where does the water enter the boat? From that point, where does it go, and where does it exit? What I suggest is checking the flow at every point along the way. First, is water entering the through hull cleanly? Is there a blockage in the strainer? If not, is it coming out of the oberdorfer waterpump in sufficient quantity? If it is, how about the thermostat? If you remove it and run the engine, does it shoot out of the thermostat housing? If so, you will need to trace each point of the exhaust system, looking for the point at which the flow is reduced. If you find reduced flow, then at least you know that the problem lies upstream. Now, if you find the problem lies in the engine (water jacket)try a product called MARSOLVE. It is a marine deposit solvent that the military has used to remove accumulated marine deposits inside engines. You will need to circulate it with a drill pump, bit it is supposedly excellent at freeing up the water jacket on old A-4's. The independant results I have heard are very inspiring, though limited in number. If my engine weren't running so well, I'd use it myself. If the Marsolve doesn't help, you may actually need to take the head off and do a serious cleaning on the jacket. Scale can, unfortunately, be a real bitch. At the very least, you will spend several hundred bucks and have a real solid engine. You may as well replace the head gasket and check the valve train while the head is off. Lastly, please keep us posted on your results, as you did last time. Everytime I hear something like this I file it away as a tool for any problems I encounter with my boat. Best of Luck, Rob
Has anyone looked at the heat exchanger?
Melody: Cannot remember if you have a fresh water cooled system or not. Assuming you do, you also need to check out the heat exchanger. If you have a 2GM or 3GM engine it is on top of the engine. You will need to remove the entire heat exchanger if it is plugged up and take it to a radiator shop. They can boil it out if it's still in good shape. Also get the mixing elbow checked out too. This is on the back side of the engine. This is not difficult to remove and inspect but can be VERY difficult to get apart. I did an article in the Photo Forum on this. Then next thing to check would be your exhaust hoses. These can sometimes cause problems. I would just do one thing at a time until you have gone thru the entire raw water intake to the exhaust side of the engine.
Melody: Cannot remember if you have a fresh water cooled system or not. Assuming you do, you also need to check out the heat exchanger. If you have a 2GM or 3GM engine it is on top of the engine. You will need to remove the entire heat exchanger if it is plugged up and take it to a radiator shop. They can boil it out if it's still in good shape. Also get the mixing elbow checked out too. This is on the back side of the engine. This is not difficult to remove and inspect but can be VERY difficult to get apart. I did an article in the Photo Forum on this. Then next thing to check would be your exhaust hoses. These can sometimes cause problems. I would just do one thing at a time until you have gone thru the entire raw water intake to the exhaust side of the engine.
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