Warm running motor |
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leftseat88
Senior Member Joined: July-06-2009 Location: Toledo Ohio Status: Offline Points: 106 |
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Posted: September-25-2017 at 12:29am |
Evening Everyone,
I have a 96 Sport Nautique GT-40 with a warm/ hot running motor. 160 degrees while running at speed, 180 while idling after that. Yesterday, I saw the water temp approach 200, luckily I was done for the day at the dock. I'm going to replace both the impeller and the thermostat just to be safe as they are old and need to be replaced. Is there a way to know which one is bad, other than a visual inspection on the impeller? Thanks |
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gt40KS
Gold Member Joined: August-05-2017 Location: Wichita Kansas Status: Offline Points: 943 |
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Don't know of a way other than removing both. Thermostat can be tested in boiling water. Make sure it's not sticking open as it cools as well. As inexpensive as they are I would replace it anyway, but testing it may narrow the search for the root problem. Impeller should be obvious. Have you checked or cleaned the sea strainer lately?
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JCCI
1995 Ski Nautique GT40 |
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leftseat88
Senior Member Joined: July-06-2009 Location: Toledo Ohio Status: Offline Points: 106 |
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I will check the strainer on Tuesday and then if that doesn't fix it, I will try the thermostat. Can I replace the impeller while the boat is in the water?
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2001SAN
Senior Member Joined: June-26-2012 Location: Ireland Status: Offline Points: 243 |
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Yup - sure can.
D. |
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A little knowledge is a dangerous thing...
2001 Super Air Nautique 1989 Fairline Corniche 31 www.bannrivercruises.co.uk |
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3610 |
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You will also need to check the clamps on each hose from the bottom of your boat to the raw water pump. If there is a air leak it can suck air rather than water. Same is true for the strainer. There is a rubber gasket in the strainer that can fail. I had the same thing happen to my 95 GT40 when I first bought it. I did all the above and changed the raw water pump impeller. Not sure which fixed it for sure but it has been perfect since. I only run the impellers 2 years and then change it. Some will run them longer but that has not worked well for me. Never had one fail on the 2 season plan.
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Jason,
Before you throw parts at the problem, I suggest getting a true engine temp with an IR temp gun. Shoot the temp next to the gauge temp sender. BTW, the 160 at speed and then the 180 dropping back to idle I consider normal. When did you get the 200 reading? |
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leftseat88
Senior Member Joined: July-06-2009 Location: Toledo Ohio Status: Offline Points: 106 |
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I got the 200 reading after running about 20 mins back to the dock. Normal temps during the run, then the temp rose to 200 after I parked at the dock. I shut down the motor immediately. 10 minutes later the temp was back down to 180.
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Jason,
Do check the accuracy of your gauge reading with an IR gun but, what you are seeing may be normal. Running hard, temp will go up then when you come back to idle water flow is low so you don't get immediate cooling. Mark suggested checking all the suction side hose connections. I too recommend that. |
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