I have a 93 2755 with 7.4L. The previous time I was out the boat ran fine until the end of the weekend. I tied up at the dock, put the trailer in at the ramp, fired the boat back up to pull on to the trailer and the alarm started sounding. All guages looked normal, so I went ahead and loaded. At home running on the hose all appeared to be fine so I didn't think too terribly much of it. Put it back in the water on Saturday and a minute after starting it the alarm started going off again. After getting out of the no wake zone all still looked ok, throttled up and about 5 minutes goes by and I notice the temp climbing. It got up to just over 200 when I decided to shut it down. Is there a sensor that detects water flow through the cooling system? I haven't traced the issue yet, but I do have the heat exchanger with antifreeze in the engine. My guess is my new impeller must have gave out, although I haven't checked it out just yet. Any ideas?
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Nobody has any ideas? I have ordered a new impeller but I haven't had time to inspect everything yet. I hopefully will be able to do that this weekend.
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I had a short overheat situation when I hit a kelp bed. Engine ran a little chunky, alarm went off, and temp started climbing. A big thank you to my friendly neighbor, Scott Conahan, who was buddy-boating with me that day - his advice saved my engine. The key for me was to not stop, but put the engine in revers, run in reverse for 5-10 seconds, go into forward for about five or so seconds, and repeat one time. That cleared the seaweed out and restored my cool water flow.
You may want to check that. Otherwise, it's a cooling system issue. Your impeller may be blocked or broken, your cooling system may be corroded and clogged, you may be leaking antifreeze... overheating an engine is a bad thing, so best to diagnose and fix this right away.
Good luck,
Rob
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Did the alarm go off when there was No flow, or once the temp rose above normal?
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You mentioned you added a heat exchanger? If you were raw water cooler prior to that, there's a good chance that it may be partially clogged as the minerals break loose from your cooling jackets. Pull the end caps off and check for obstructed tubes. It's a very easy check with one bolt holding the cap onto each end.
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I didn't add the heat exchanger, it was on it from the factory as this boat has spent most of it's life in saltwater. The clogging is possible since I know the impeller was bad when I bought it, and I hooked the hoses up backwards once and burned up another. I tried to flush out all I could, but some might still be there.SomeSailor wrote:
You mentioned you added a heat exchanger? If you were raw water cooler prior to that, there's a good chance that it may be partially clogged as the minerals break loose from your cooling jackets. Pull the end caps off and check for obstructed tubes. It's a very easy check with one bolt holding the cap onto each end.
My biggest question is if there is a sensor that detects water flow through the system. The alarm starts going off about 5-10 seconds after you fire it up, so the alarm is not a temperature related alarm, and I didn't know these had any sort of flow sensor.
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No, I don't think the sensors know about water flow. Perhaps you have low oil or outdrive lube levels as well as the cooling issue.
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Thermostat maybe. Seems pretty fast for a thermostat though.
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pull the ends off your heat exchanger and check for blockage,
If you can get at the hose coming up from your sea water pump, pull it off and start her up you will quickly see if it is pumping any water.
It shouldn't go past 175 under normal operating conditions.
As someone suggested the alarm could also be the outdrive oil level, check the reservor.
Steve
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Well, two issues at once. 1. the alarm was from the outdrive oil level. I had checked it before the weekend of the first alarm so I didn't think that would be it, but i think there was an air pocket somewhere. Filled it and the alarm went away, so it's good to know that alarm works. The overheat was actually that i was low on antifreeze. I'm not sure where it went, every time I have checked it it was right at the top and plenty green. It took almost a gallon to get it filled again, so i'm going to have to watch this better and see where it was going. I know for a fact it was not overheating when the alarm first went off, but did on the very next trip within 1 mile of the no wake zone so i thought they were related. Both problems solved, but they will need more investigation to make sure it doesn't become a bigger issue. Thanks for the pointers of where to look for the issues.
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