Raw water pump works in driveway...not in lake???

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   Hello, all.  Running a GT-40 in a '96 super sport.  In my driveway...detatced water filter...clamped a hose to the water intake...placed other end of said hose into a bucket on the ground next to my boat + trailer.

all good.  Sucked up about 10 gallons of water...temp stayed at 120, and I felt the impeller housing to ensure it was cool-to-the-touch.

Then took her to the ramp.  Launched.  reversed back about 40 yard.  Temp started to climb past 120...130...140....oh S****!!!

felt the impeller housing...super hot.

Any idea why I'd be able to pull water just fine from a bucket...but not from the lake?

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jackkloepfer Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: October-28-2008 Location: United States Status: Offline Points: 152	Post Options Post Reply Quote jackkloepfer Report Post Thanks(0) Quote Reply Topic: Raw water pump works in driveway...not in lake??? Posted: June-25-2024 at 3:57pm
	Hello, all. Running a GT-40 in a '96 super sport. In my driveway...detatced water filter...clamped a hose to the water intake...placed other end of said hose into a bucket on the ground next to my boat + trailer. all good. Sucked up about 10 gallons of water...temp stayed at 120, and I felt the impeller housing to ensure it was cool-to-the-touch. Then took her to the ramp. Launched. reversed back about 40 yard. Temp started to climb past 120...130...140....oh S****!!! felt the impeller housing...super hot. Any idea why I'd be able to pull water just fine from a bucket...but not from the lake?

Wilhelm Hertzog Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Senior Member Joined: June-14-2014 Location: Cape Town Status: Offline Points: 334	Post Options Post Reply Quote Wilhelm Hertzog Report Post Thanks(0) Quote Reply Posted: June-25-2024 at 4:43pm
	Clogged thru-hull intake grate and/or strainer?
	1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer Do not go gentle into that good night. Rage, rage against the dying of the light.

RealDeez Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: August-01-2019 Location: MI/IN Status: Offline Points: 130	Post Options Post Reply Quote RealDeez Report Post Thanks(0) Quote Reply Posted: June-25-2024 at 6:21pm
	By intake, do you mean the intake side of the RWP, or some other location? You may have bypassed some potential leak locations.
	Lake James, IN 93 Sport Nautique

LooseScrew22 Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: August-05-2022 Location: Oregon Status: Offline Points: 54	Post Options Post Reply Quote LooseScrew22 Report Post Thanks(0) Quote Reply Posted: June-25-2024 at 8:35pm
	My '95 SN (not a GT40) came with a hose adapter inline after the strainer, but i added a ball valve so i can control the water from flowing out the intake. I leave the valve open on starting then shut it off most of the way when running. My temp stays at 160 degrees. I expect your intake is blocked somewhere or your impeller crapped out

Jonny Quest Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2957	Post Options Post Reply Quote Jonny Quest Report Post Thanks(0) Quote Reply Posted: June-25-2024 at 11:24pm
	Sounds like you fried your impeller. Time for a new one. If the impeller housing is hot…impeller is toast. Your raw water hose should have a bit of a “downhill“ run to The impeller. That helps maintain prime so that the impeller has water to maintain a suction seal. Almost like a P trap in a sink drain. JQ
	Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum

MrMcD Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3735	Post Options Post Reply Quote MrMcD Report Post Thanks(0) Quote Reply Posted: June-26-2024 at 2:38am
	Maybe when you re installed the filter after your bucket test the hose did not seal completely. If the hose allows air to be sucked in the pump will never suck water. JQ is correct, after running your pump dry and getting it hot the odds are very good the impeller fell apart. If it did, you will need to search all the coolant lines till you find all the missing parts of the old impeller. If parts of the old impeller are in your system you will have cooling issues till you dig them out. Almost all of us have done this or been there when a friend did it. I doubt any of us did it twice though. I was 25 when I bought my first Nautique, a 1978 purchased in 1982, at that age I flat out loved the sound of the engine firing up with the straight pipes and no mufflers. Fired it up several times just to hear it before taking it to the water the first time to find out I had wiped out my impeller. Lesson learned. Read up on adding a TimmyT to your boat cooling system, it is much easier than a bucket for driveway tests.

Raw water pump works in driveway...not in lake???

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