Stus-List Yanmar 2gm fuel pump seepage

sender victoriaenergy at gmail.com
Fri May 10 01:13:56 EDT 2019


Dave:
The copper washers are intended to be a single use seal, so your supposed
to replace them every time you loosen a banjo bolt so maybe not the best
places to bleed.  I don't know if the Mcmaster-Carr ones are intended to be
multi use.  The fuel will harden the o-ring material if it's made from the
normal Buna-N material.

All your fittings should be bone dry with no seepage.  If fuel can seep out
when the engine is running, it becomes possible that air will seep back in
when the engine sits unused for a long time.

Yanmar has sold millions of those filter housings due to people stripping
them out.  The nylon washer under the bleed screw makes it so it will seal
effectively with a 1/4 turn past finger tight.  It's not vey tight, but it
does stay dry.

I use the Yanmar filter as a redundant filter.  The common practice is to
run 25 micron element in the racor (or similar) prefilter and then have the
yanmar filter the finest particles out.  Instead of that, I run a larger
500 Racor with the finest 2 micron (I think) element in it.  The Yanmar
element I no longer change since the only contamination it will ever see is
the tiny bit of dirt that may accidentally get introduced when I'm changing
the Racor.

The secondary benefit of this arrangement is I never need to bleed the
system. (...Well OK, I do crack the bleed screw on the Yanmar it to check
it, but that's me being overboard curious, never any air in there.)  You
turn off the fuel at the tank (keep it from flowing back when you take the
lid off the racor), pull out the old filter element, drop in the new one,
change the lid seal, pour a bit of diesel on top to fill the filter to the
brim, put the top on, turn the fuel back on and I'm done.

I think it's a good idea to do a P-M replacement of the fuel pump.  Also
the standard exhaust mixing elbow on that engine is problematic and should
be replaced on P-M as well.

Eric

On Thu, May 9, 2019 at 6:38 PM Josh Muckley via CnC-List <
cnc-list at cnc-list.com> wrote:

> If you don't know the age of the pump it would be prudent to replace it.
> It is an engine vulnerability in that when the diaphragm fails it will leak
> fuel into the crankcase.
>
> I replaced all my copper washers with seal washers or dowdy washers
> available on Amazon or McMaster Carr.
>
> https://youtu.be/F7KD1_EZmU4
>
> Josh Muckley
> S/V Sea Hawk
> 1989 C&C 37+
> Solomons, MD
>
>
>
> On Thu, May 9, 2019, 11:09 AM Dave S via CnC-List <cnc-list at cnc-list.com>
> wrote:
>
>> From both pumps oddly enough....
>>
>> Lift pump seeps, appears to be gasket and or crush washers on banjo
>> fitting.  I’m wondering whether in addition to replacing the gaskets I
>> should also replace the (still operating, likely original) pump for
>> reliability’s sake.  Thoughts?
>>
>> High pressure pump has very minor seepage as well.    Can’t see what’s
>> causing it.  Any likely scenarios?
>>
>> Many thanks!
>>
>> Dave 33-2
>>
>> Sent from my iPhone
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