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temperature flucuation |
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phospher 
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Joined: July-19-2007 Location: United States Status: Offline Points: 557 |
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 Topic: temperature flucuationPosted: April-28-2021 at 10:43am |
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Hi, I have a 2002 ski nautique. GT-40 800 hrs. Sits in heated building during winter months..After I buttoned her back up and took her for a lake test I noticed that my temp gauge is running 165 up to 180 and when it hits 180 (or slightly under) it falls back down to around 165 - seems to repeat this cycle even at idle. I've went through and checked that all my hoses are tight and no water is leaking along the raw water circulation path. I have about 80 hours on the impeller - have not checked it yet but I'm doubtful it's not in good shape as it always is when I change them out typically every other year. I also have a water strainer which appears tight and leak free. One other thing I noticed which may be unrelated.. I hear a hiss (like an air leak) after shutdown coming from the rear of the engine or transmission but I'm having a hard time isolating the noise. At any rate, I don't think the temp used to bounce like this, what are your thoughts and perhaps what should I check next? Thanks!! And about ski time in Wisconsin!!
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Jonny Quest
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Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2979 |
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Posted: April-28-2021 at 10:49am |
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Could be a thermostat that is sticking. That is a quick and inexpensive fix.
JQ
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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Nautiquehunter
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Joined: December-31-2008 Location: Lake Lanier GA Status: Offline Points: 1010 |
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Posted: April-28-2021 at 11:54am |
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Block off the hose coming out of the RWP remove the intake hose at the bottom of the bilge . Attach a garden hose to the intake hose and pressurize the suction side of the system . Look for water leaks . It will be easier to spot than vacuum leaks. PCM only on new impellers Nautique Parts only sells PCM.
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8122pbrainard
Grand Poobah
Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Posted: April-28-2021 at 12:03pm |
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I agree with JQ regarding the T stat sticking. If it was the RWP impeller, then the temp would go up and not come down.
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phospher
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Joined: July-19-2007 Location: United States Status: Offline Points: 557 |
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Posted: April-28-2021 at 4:18pm |
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Gents, Appreciate the help. I took the thermostat out and put it in boiling water. The stat doesn't start opening until 170+ and all the way around 180. That seems pretty consistent with my issue. Headed to the inboard marina to pick up the replacement thermostat part #RP026002.
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phospher
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Joined: July-19-2007 Location: United States Status: Offline Points: 557 |
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Posted: May-13-2021 at 12:05am |
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So I replaced the thermostat with a new 160 degree PCM stat from nautiqueparts.com. Unfortunately it did not fix the issue. Boat seems to run fine the only issue being that the thermostat goes from 160-180. I double checked all hose connections, raw water strainer, drained the manifolds to make sure no debris, checked both sides of the tranny cooler for debris, and checked the hoses that run from the thermostat to the manifolds for any blocks. I wasn't able to find any leaks or blockage. On another note, I figured out what the hiss/air leak was. I had a crack in my muffler. After a bit of work to get all the hoses off (and without cracking or breaking anything) I pulled the muffler, sanded it down, cleaned it really good with acetone and used bondo glass to patch the cracks. When I reinstalled I put additional foam under the muffler to prevent future cracking. After the lake test it was leak free so appears to have gone well. But this temp fluctuation is driving me bonkers! One thing I did last night was to clean the connections from the temp sensor (one with brown wire that I think goes to gauge) but at this point I might be grasping for straws. Any other ideas on the temp fluctuation issue? Thanks!
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WakeskateNW
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Joined: December-08-2016 Location: Lake Tapps, Wa Status: Offline Points: 65 |
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Posted: May-13-2021 at 12:30am |
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Maybe another look at the raw water strainer? I fixed my wandering temp by taking it apart and then reassembling. It was sucking air through one of the fittings. I never noticed any leaking water so maybe even though you are not seeing water leaks anywhere perhaps air is still getting in. If you can rotate your strainer look for bubbles passing through as you move it. That was the dead giveaway for mine.
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phospher
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Joined: July-19-2007 Location: United States Status: Offline Points: 557 |
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Posted: May-13-2021 at 12:32am |
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Will definitely check the water strainer for bubbles next time out. Thanks for the tip.
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SNobsessed
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Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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Posted: May-13-2021 at 7:38am |
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You might want to get an IR thermometer (about $15) & verify the temps. Maybe it is your gauge or sender.
The scanner is useful for many other things too, like checking brake rotors for even temps, bad electrical connections, etc.
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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Nautiquehunter
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Joined: December-31-2008 Location: Lake Lanier GA Status: Offline Points: 1010 |
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Posted: May-13-2021 at 8:03am |
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I would change the impeller with a Sherwood brand . There are a lot of cheap imported impellers out there that look good but don't work consistently.
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TRBenj
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Joined: June-29-2005 Location: NWCT Status: Offline Points: 21186 |
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Posted: May-13-2021 at 10:07am |
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165-180 look like pretty normal temps for a 160 stat to me.
By all means check your hoses and connections and change the impeller with a good sherwood/pcm (depending on how/when you see the fluctuations) but the 180 temp itself isn’t concerning. |
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Jonny Quest
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Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2979 |
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Posted: May-13-2021 at 11:45am |
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I have had bad luck with PCM temp sensors in the past. On my 1994 SNOB I replaced 3 temp sensors for going wonkey. So far my 2001 SNOB temp gauge and sending unit seem to be OK.
JQ
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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