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Sunscape Doug

Overheating

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Sunscape Doug

I am a new owner of a used 2002 21' Sunscape LSV. I replaced the impeller before my first launch and found that the old impeller was badly damaged. After fishing out rubber pieces parts and replacing the impeller, my test runs worked great. Then I took the boat to Lake Powell for a week-long trip. Ran fine for 60+ miles down to the San Juan and then began to overheat (may have been overheating during this trip, but I did not notice it).

It appears that the impeller is not putting enough water into the system since the hose after the thermostat but before the water pump is collapsing when the speed exceeds 20 mph or so (don't know the RPM's since my guage is not working).

I have checked every part of the cooling system to the water pump. Checked the scoop for blockage, checked all hoses, checked the screen before the transmission oil cooler, removed the thermostat since I was concerned this was corroded. Nothing seems to work and the boat begins to overheat at speed and even at idle, moving up to 200 degrees.

Any ideas? I think it must have something to do with my impeller, but I replaced the fan again and have the same result.

Any help would be greatly appreciated. I am going to take it to Tommy's Slalom Shop in Denver on Thursday, but thought I might ask here for advice since a mechanic in Lake Powell had no idea what could be causing the problem.

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jgouveia3

what condition are the exhaust manifolds and risers in?

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Sunscape Doug

The exhaust manifolds appear to be fine. I am not sure what you mean by the risers. Are these the hoses going into the manifolds?

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NorCaliBu
I am not sure what you mean by the risers. Are these the hoses going into the manifolds?

The risers are the cast piece bolted to the exhaust manifold that...rises. :lol: It's where water enters into the exhaust cooling picture. It's what the hoses attach to.

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jgouveia3
The exhaust manifolds appear to be fine. I am not sure what you mean by the risers. Are these the hoses going into the manifolds?

no, the risers are what are attached to the top of you manifolds. if there are any restrictions in them, they can cause overheat issues. it does not occur to often with boats strictly run in fresh water, but salt water boats have to keep an eye on both. I run strictly in salt water, and even though i flush after most uses, the salt still eats up exhaust components (i also have FWC, so internal engine components are not an issue). 2 years ago i had one riser that even though looked brand new on the outside, all the passages where almost completely stopped up, and causes overheat issues. Again this is not common, but since it sounded like you checked everything else, it could be a problem for you.

another thing you could check is your thermostat, not sure if you did that or not. pull it and stick it in a pan with water, a thermometer and heat it up. see what the temperature is when it opens up. should be 160.

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Sunscape Doug

I have the boat into Tommy's Slalom Shop now and will let you know what they find - the risers were clear as well.

With regard to the thermostat, I took it out and ran it - still overheated, so it can't be the thermostat. I am going to have it replaced just for good measure - it was pretty corroded.

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UWSkier

blockage at the transmission?

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Sunscape Doug
blockage at the transmission?

Could be, but I ran water through the transmission box and have checked the screen in front of the oil transmission cooling unit.

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VinRLX

Wrong impeller or cover of impeller housing not tight enough to form a new seal? Did you replace the gasket along with the impeller??

And don't listen to Michael, he'll probably tell you that your bimini is creating a vacuum or something.

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NorCaliBu
And don't listen to Michael, he'll probably tell you that your bimini is creating a vacuum or something.

Excuse me Jack(off), I'm not the one making ridiculous mechanical recommendations. Fingerwag.gif

Aren't you going to recommend that he check the alignment of something unrelated? Crazy.gif

Edited by NorCaliBu

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Sunscape Doug
Wrong impeller or cover of impeller housing not tight enough to form a new seal? Did you replace the gasket along with the impeller??

And don't listen to Michael, he'll probably tell you that your bimini is creating a vacuum or something.

I think this could be it. I had a problem when I changed out the impeller the first time - one of the brass bolts twisted off when I was tightening it and I had to have it drilled out. I use a longer brass screw for this bolt and it seems to be fine, but I am very cautious about tightening the brass bolts too tight. I did replace the gasket, but maybe I didn't get it tight enough and it is letting in air. It does not leak any water, but maybe it is sucking in air into the impeller. When I took the plate off after overheating to replace the impeller again, the gasket had impressions on it from the plate and impeller, so it seems tight enough, but maybe I need to relook at this.

Still no word from Tommy's who is working on it now - I'll let you know what they say.

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VinRLX
And don't listen to Michael, he'll probably tell you that your bimini is creating a vacuum or something.

Excuse me Jack(off), I'm not the one making ridiculous mechanical recommendations.

Wrong impeller or cover of impeller housing not tight enough to form a new seal? Did you replace the gasket along with the impeller??

I think this could be it.

There, see Michael. You can :biteme:

Doug, hope it's a simple fix.

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NorCaliBu
Doug, hope it's a simple fix.

Because that's the only way you have a prayer at guessing the possible solution. :lol:

As far as you coming up (possibly) with the correct diagnosis...hey, even a blind squirrel finds a nut every now and then. ROFL.gif

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VinRLX

Well, at least that explains how your wife found you. :lol:

Tease2.gif

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NorCaliBu
Well, at least that explains how your wife found you. :lol:

:lol: Hey!! Mad.gif

Stop hi-jacking this thread. Fingerwag.gif Post Count Ho.

Edited by NorCaliBu

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SmoothWaterMan

I'm sure Tommy's will fix it, but just for reference, I don't believe taking out the thermostat will ensure that water flows through the block and cools it. It may just keep running hot without it.

Peter

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