Bruce,
On my 1994 37/40+ there is an access port in the head bulkhead. This makes it 
easier to work on the raw water pump and starter. I don't know how you would 
access either without it. 
You might want to dress the face of the pump with a smooth flat file, just to 
remove a thigh spots that might be preventing the cover from solidly contacting 
the oring 

Al Liles
SV Elendil
Vancouver 


> On Jun 7, 2017, at 7:42 AM, Charlie Nelson via CnC-List 
> <[email protected]> wrote:
> 
> Note that you may also have an O ring or 2 on the shaft that the impeller 
> turns on that are on the engine side of the impeller. On my Beta, there were 
> 2 O rings between the impeller and the engine--these keep the water out of 
> the crankcase, etc.
> If these are bad or the shaft is 'scored', replacing impellers, or O rings on 
> the non-engine/impeller side of the shaft will not solve your problem.
>  
> In my case the shaft was 'scored' and I needed to replace the entire pump 
> assembly since the Beta shop could not reasonably remove the scoring.
>  
> Charlie Nelson
> Water Phantom
> C&C 36 XL/kcb
> Oriental, NC
>  
> [email protected]
>  
>  
> -----Original Message-----
> From: Neil Gallagher via CnC-List <[email protected]>
> To: cnc-list <[email protected]>
> Cc: Neil Gallagher <[email protected]>
> Sent: Wed, Jun 7, 2017 10:18 am
> Subject: Re: Stus-List Yanmar 3JH2E leak around water pump impeller cover
> 
> Bruce,
> 
> The issue with putting a gasket under the cover is that now the cover will be 
> moved away from the edge of the vanes of the impeller.  The pump works by 
> creating a vacuum in each space between the vanes at the inlet as the 
> impeller vanes open up and pressure when the vanes close down a the outlet.  
> The vanes need to contact the cover to create a seal, that's why an o-ring is 
> used, it keeps the cover in contact with the edge of the vanes.  Bottom line, 
> the gasket would have to be very thin not to affect the pump's performance.  
> 
> On some pumps you can buy a new cover as well as the gasket because the cover 
> wears, I'm not sure about the Yanmar.
> 
> Neil Gallagher
> Weatherly, 35-1
> Glen Cove, NY
> 
> On 6/7/2017 8:51 AM, Bruce Whitmore via CnC-List wrote:
> Hello,
> 
> I replaced the impeller on a Yanmar 3JH2E about a month ago, and I was 
> checking over the engine last weekend and noticed some wetness coming through 
> around the impeller cover.  I tightened the cover bolts (they were not really 
> loose), and the leak still continues.  When I replaced the impeller, I also 
> replaced the o-ring, so that should not be the issue.  That said, the old 
> o-ring had a tear (the cover was leaking, though more so then).  The face of 
> the water pump was also a little rough, presumably from people prying  with 
> angled needle nose pliers in the process of removing the old impeller.  That 
> said, the cover itself was smooth, and the groove for the o-ring was fine as 
> well. 
> 
> I personally don't like the idea of relying on Yanmar's very thin o-ring for 
> sealing something that is below the water line.  I am thinking about getting 
> some thin cork gasket material, and cutting a proper gasket, applying teflon 
> grease to it, and using a gasket instead.
> 
> Is this a bad idea?
> 
> By the way, our boat is a 1994 C&C 37/40+, and the way the engine is mounted 
> in the boat, it is nearly impossible to get to the bolts to remove the water 
> pump, and even removing the starter is not exactly a fun job, again due to 
> poor access to mounting bolts. 
> 
> Thanks for your insights! 
>  
> Bruce Whitmore
> 
> (847) 404-5092 (mobile)
> [email protected]
> 
> 
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