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Where's it leaking?


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Boat ran flawlessly last season.  Usual oil change and winterizing routine at end of year.  De-winterized two weekends ago.  Took boat out for maiden voyage this year and it ran great.  Temperature was fine.  Oil pressure was good.  Totally unremarkable run.  When finished, after putting the boat up on a lift at the marina, I changed the impeller.

 

Two days later, I went up to lake to finish up waxing  the gelcoat and 303ing the interior, only to discover about 5 gallons of water in ski locker (21 LSV Sunscape, so no ballast tanks).  Vacuumed it all out, but ran out of time to do a further assessment.

 

Went up today and ran the boat again for about 30 minutes after double-checking all hoses and clamps.  No leak at idle, but at higher rpm/under load, its obviously leaking from somewhere.  I was by myself, so I couldn't simultaneously investigate for leak while driving the boat.  There was spray up on top of engine and hatch cover, and spray on starboard side partition (v-drive configuration), probably all thrown by the belt, but, again at idle, I could not see the source.  I felt all along the hoses and couldn't appreciate any obvious problems.   Exhaust manifolds, and plastic elbows, were completely dry.  But, water has got to be squirting out from somewhere.  I wouldn't think it'd be the rear seal of the raw water pump because, unless it were spraying upwards instead of dripping downwards, I can't account for the water up top.  Could it be the engine's circulating water pump (though, the temperature was normal, and I didn't hear any unusual noise)?

 

I'll have to go out again with someone who can drive while I'm lying down in the starboard side storage with a flashlight.  I was hoping for an easy fix, but I'm starting to get discouraged.  Any ideas?

Edited by srab
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Check the transmission cooler.   I overtightened my hose clamps and pinched the cooler, it's  very soft and can bend easily.  I did this when I replaced the cooler hose.

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7 hours ago, srab said:

No leak at idle, but at higher rpm/under load, its obviously leaking from somewhere. 

Does it only happen under load? or also at higher RPM without spinning the prop?

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Could you be leaking at the shaft seal and it coming off the shaft well running?  Seals leak in the spring often. After some water time they will swell and slow down but may also need adjusting. 

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Thanks for the input. 

I was too chicken, once I thought about it, to disengage the transmission, rev the engine, and jump down into the rear starboard storage, lying on my side, to visualize.  I'm sure it would have been safe, and I guess I could have rigged an extension so I could pull the kill switch from way back there just in case it somehow slipped into gear, but I just couldn't convince myself that that was a good idea.  So, not sure if it is rpms or load that produces the leak.

Impeller housing cover is on snugly with new gasket.  I'm always reluctant to tighten those brass screws much beyond snug, lest they snap off, but I've never before had a problem there.

I paid close attention to all hose clamps, but especially those that I loosened to winterize, including that J hose from the thermostat housing (The lower end of that hose is the only side I disconnect when draining, and the dependent edge of that hose showed nary a drip).

I didn't pull the hose from the impeller housing to the transmission cooler yesterday to inspect, but I have always been hesitant to over-tighten that clamp as well because of concerns that I'd crush the cooler barb.  Not saying I couldn't have, but only that I don't think I did.

I have a water-cooled shaft seal, and the clamps on both ends of that clear hose were tight.  I looked, but could find no obvious cracks in that hose, and no dripping at idle.  Plus, on my v-drive, I think the shaft itself is too far forward to account for the splatter pattern I saw.

I'm just gonna have to go back out, hopefully with a little more daylight to work with, and definitely with some extra help.  I just have to find the time.

 

Edited by srab
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23 minutes ago, srab said:

Thanks for the input. 

I  I'm always reluctant to tighten those brass screws much beyond snug, lest they snap off, but I've never before had a problem there.

good call.  those brass machine screws are torqued to inch pounds not ft. lbs.

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Check clamps around the exhaust exit ports on the transom.  I had a small leak there one spring and had to tighten them.  Also, just for a sanity check shut everything down and listen.  If you have water dripping you may hear it.  That's how I found the exhaust leak.  Good luck.

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On 4/23/2016 at 0:47 AM, Shastasurf said:

Check the transmission cooler.   I overtightened my hose clamps and pinched the cooler, it's  very soft and can bend easily.  I did this when I replaced the cooler hose.

FTW!!

Made it back out to the lake today with my wife.  With her at the helm and me lying down in the starboard side storage, with a bit more RPMs, a progressive leak was evident on the proximal side of the transmission cooler.  I loosened the hose clamp and pulled the hose.  At first glimpse, with my head on the floor looking up into the mouth, it appeared to be normal, and I thought maybe I'd just not quite tightened that hose enough.  But, on closer inspection, there was a flat spot.  After gently prying the flat spot outwards with a screwdriver shaft, I rotated the hose clamp tightening screw to the opposite side, plugged the hose back in over the barb, and re-tightened the clamp.  And, problem solved.

Thanks again to the Crew for all the input.  Hard to believe that, after 10 years of doing it the same way, and knowing beforehand that over-tightening the hose clamp on the transmission cooler is problematic, I managed to make the rookie mistake anyway.

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