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Temporary Over Heating


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First time out last weekend following a 50 hr service and we didn't get past the 5 m/h buoy before the sensor indicated a temp problem. After letting sit I restarted and when I pushed the RPM's a bit the engine cooled immediately. I let idle for about 20 mins with no over heating, ran great. After lounging for about an hour the boat started to overheat when I started it again but reving the motor cooled it right down again. We boarded for about an hour after this with no issues. What should I be looking at to explain this?

I checked the new impeller and it looks fine. What should be the next thing to check?

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First time out last weekend following a 50 hr service and we didn't get past the 5 m/h buoy before the sensor indicated a temp problem. After letting sit I restarted and when I pushed the RPM's a bit the engine cooled immediately. I let idle for about 20 mins with no over heating, ran great. After lounging for about an hour the boat started to overheat when I started it again but reving the motor cooled it right down again. We boarded for about an hour after this with no issues. What should I be looking at to explain this?

I checked the new impeller and it looks fine. What should be the next thing to check?

Did your last impeller go to pieces before it was replaced? The reason I ask is that there may be pieces in the tranny cooler that are blocking water flow to motor. I had my impeller shred on me and found a complete blockage at the cooler.

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Sounds to me like you are getting water just not much at slow speeds.

Exactly what I was thinking, check the tranny cooler, then lake pick up for junk in it, then the entire intake line for crap.

Did this just come out of winter storage... if so where the enginee plugs put back in properly.

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One other thing to check, since it was just mentioned in another thread that the engine drain holes were actually open letting water in the boat. Lift your engine housing and make sure you have everything closed (valves) and all the hoses and clamps are tight "if any were off when winterized".

Welcome to the board Thumbup.gif

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Yes the boat just came out of winter storage and Yes the old one came out in pieces which was saved for me by the local shop that did a 50 hr service two weeks prior to my first run. I thought they would have checked the trany filter? Besides the filter in the hose where the trainy coolant lines run is there any other filters further back towards the motor I should be checking. Sorry, I have no clue what the technical names of the parts are.

Thanks for the response.

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There really aren't any filters in the water path. The tranny cooler isn't a filter either, it just sort of acts like one. The grid inside that catches debris is the heat exchanger making it a tranny "cooler". It's good to check this every now and then regardless of the impeller. I've found mine jammed up with weeds too.

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Another possibility is an air leak between the impeller and the inlet. If there is a cracked hose, bad gasket in the impeller cover, loose hose connection, etc... then the impeller may not prime until you have cranked up the rpm's because it is drawing air. Once primed, it will most likely function fine.

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Check the tranny cooler screen. I'm willing to bet there is a whole host of old impeller parts in there ;)

Plus1.gif

Thats my guess!!! However, if there is nothing clogging the screens when you check them, there is the remote possibility that they used the wrong impeller when they replaced your old one - if its too small, it will have trouble priming.

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Another possibility is an air leak between the impeller and the inlet. If there is a cracked hose, bad gasket in the impeller cover, loose hose connection, etc... then the impeller may not prime until you have cranked up the rpm's because it is drawing air. Once primed, it will most likely function fine.

I checked the hoses and looked for any leaks and could find nothing. Would the impeller housing leak if there was not a good fit or bad gasket? It was not leaking.

Also, I confirmed that the proper impeller was used and it was.

If the tranny screen is clear could the problem be with the thermostat? If so how would I check this?

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