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383 Hammerhead not cooling (2006 Wakesetter 247 LSV)


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A very long story short, believe there is something blocking the flow of fresh water as it flows though the manifold on the right side of the engine, as you are looking from the back.  Water used to come through both sides fairly equally, but has since all but stopped completely on that side.

To give a little more detail, the boat overheated the other day and I believed it to be a sensor at first, however that turned out not to be the case as it tested just fine.  I then replaced the thermostat, and when I took the cover off, there were two pieces of what appear to be gasket material that were sitting on top of it.  Believing I had found the issues, we gave it a go, but the problem still remained.

I then began checking the hoses and found that the previous owner had used a metal ribbed hose, metal on the inside, to run fresh water from the Johnson impeller, to the oil cooler, and that there was a kink in it that was not previously there.  A closer inspection revealed that some of the metal rings had rusted through and broken, thus causing the kink.  Several pieces of metal were pulled from the screen just inside the oil cooler, but it appears to have caught them before they went through the engine......... I hope.

Just today, I replaced the hose with the factory part, as well as replaced the Johnson Impeller, which wasn't too bad.  Again believing I had fixed it, I ran it in my driveway with the fake-a-lake and was able to get it to overheat again and there is still not enough water coming out the right side exhaust.  All other hoses have been removed and inspected for blockages and all are in great shape.

So after all that, I was hoping to get some guidance on where to look next.  Remove and inspect the manifold on that side?  Does it require anything special?  Is it something I can do?

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Update...

I took the manifold off, connected my garden hose to it and it appeared to work just fine.  I then re-checked all the hoses for blockages, but there were none. re-inspected the oil cooler and it appears to be clear from debris as well.

After putting everything back together, I ran it again but was able to get it to overheat and there was still no water coming out of the right side of the exhaust.

To see how much water was getting to the manifold, I disconnected the supply hose and ran the engine until water came out.  There was pretty good flow.  I then did the same thing on the left side and the water flow was about the same, thus adding to my confusion.

At this point I would tend to believe it was the temp senor, but that still does not explain the lack of water flow from the exhaust.

After all day trying everything I could think of, the engine still surpasses 160 degrees and overheats.

I know I have to be missing something.  Anyone have any ideas????????????????

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A common reason for overheating is a leak in an intake hose or on the intake side of the pump.  Air is much less viscous than water, so it will come through a small gap and displace water that should be there.

Depending on your garden hose, this could still happen on a hose since the raw water pump is rated at 60 gallons per minute at higher speed.  If the hose can't provide, you will still suck air.

Check all hose connections very carefully.  Consider using some goop when you put them back on.

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Depending on how the boat is sitting on the driveway more water could be going to one side or the other and this could also be true of the way the muffler is slanted inside the engine bay.  

If you had an overheating episode, a baffle could have partially melted inside the muffler and could be causing a blockage.  

May need to check your circulating pump not the raw water pump.  Had to replace mine once due to the brass impeller being broken.  

How is the impeller on the raw water pump?  The rubber fins?  Did the cover get sealed well?

My original J-hose did not have the metal "spring" wire inside and thought that it was collapsing on the inside.  Bought the newer version and it had the wire on the inside.     

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On 8/29/2021 at 6:05 PM, justgary said:

A common reason for overheating is a leak in an intake hose or on the intake side of the pump.  Air is much less viscous than water, so it will come through a small gap and displace water that should be there.

Depending on your garden hose, this could still happen on a hose since the raw water pump is rated at 60 gallons per minute at higher speed.  If the hose can't provide, you will still suck air.

Check all hose connections very carefully.  Consider using some goop when you put them back on.

So taking your advice, I did check and recheck the hoses at the connection points and they all seemed fine.  I did replace a questionable hose clamp as well, but I still had the same issue.  I also dried things out and rechecked for any water leaking from anywhere, but everything appeared as it should.  Still at a loss as to what it could be.

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6 hours ago, blk93jeepzj said:

Depending on how the boat is sitting on the driveway more water could be going to one side or the other and this could also be true of the way the muffler is slanted inside the engine bay.  

If you had an overheating episode, a baffle could have partially melted inside the muffler and could be causing a blockage.  

May need to check your circulating pump not the raw water pump.  Had to replace mine once due to the brass impeller being broken.  

How is the impeller on the raw water pump?  The rubber fins?  Did the cover get sealed well?

My original J-hose did not have the metal "spring" wire inside and thought that it was collapsing on the inside.  Bought the newer version and it had the wire on the inside.     

The engine sits really flat and square in the boat and the boat is centered very well on the trailer as well.  The driveway is pretty much as flat as it can be, although there is a slight difference in the exhaust can after the manifold, but its not enough to make a difference.

The raw water pump appears just fine.  I replaced the impeller and the old one was fully intact and seemed to be in pretty good shape.  Even replacing that didn't fix anything.

I think you are on to something with the circulation pump.  My inexperience will be showing on this one as I thought the fresh water pump did all the work and that there was not a circulation pump as well.  After becoming "YouTube Certified", I think that is exactly my issue and will take it off in the next day or so.

Thanks for the heads up.

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The circulation pump will generally help at or near idle.  Above that, the raw water pump should have enough flow even if the circulation pump is broken.

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8 hours ago, justgary said:

The circulation pump will generally help at or near idle.  Above that, the raw water pump should have enough flow even if the circulation pump is broken.

Opposite of my experience.  I would get an overheat alarm (or see the gauge right before an alarm event) while we were surfing or boarding or cruising.  Could then pull the throttle back to neutral and watch the temp gauge slowly come back down to 160.  Took quite a few weeks to finally determine the issue, intermittent at best and tried multiple things before we got to the circulating pump. 

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29 minutes ago, blk93jeepzj said:

Opposite of my experience.  I would get an overheat alarm (or see the gauge right before an alarm event) while we were surfing or boarding or cruising.  Could then pull the throttle back to neutral and watch the temp gauge slowly come back down to 160.  Took quite a few weeks to finally determine the issue, intermittent at best and tried multiple things before we got to the circulating pump. 

Well there you go.  Either way, the circulation pump is easy enough to get to, and it certainly is in play for cooling the engine.

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So I ordered a new circulation pump but wanted to test a few theories before I installed it.  I pulled the trailer up on blocks on the left side, which is the side the water is coming out for the exhaust.  Once the engine was running, the water still only flowed out of the left side.  I watched several YouTube videos of guys with similar boats and they all seemed to come out both sides fairly equal so I am still lost about why mine does not.  It seems like no matter what I do, the water will only flow out the left side exhaust and just trickle out the right.

 Then, taking your advice, I replaced the circulation pump and found the culprit.  The impeller inside was completely broken in half and there was no possible way it was working.  Once it was replaced, which wasn't too bad of a job, I again ran the boat on the fake-a-lake to see if I could get it to overheat.  Thankfully, all seemed to work as it should, but the water was still only going out the left side.

Unable to figure it out, we took it to the lake today and it ran like a champion.  No overheating!!!!  Both manifolds were cool to the touch, even after running at 4200 rpm and 38 MPH for about 30 straight minutes.  Watching the gauges very closely, it managed to squeak up to about 165ish, but would always come right back down to 160.

Seems like I may have taken care of the overheating problem.

Thank you to everyone who offered suggestions and provided feedback.  There is no doubt I would still be lost trying to figure it all out without your suggestions.

Thanks again

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