The unpleasant case of the haunted yanmar
 

Dearest engine wonks,

I have a yanmar 2gm20f with sd20. When it's cold and it comes under
load (eg. the alternator starts developing more than 20 amps) it is
unable to hold its rpms. Typically it runs easily up to speed but then
as the load kicks in it drops back down to idle and then revs back up
past the throttle setting and then drops back down again. Sometimes is
stalls. Once it has gotten warm it runs like a top. There is no
visible smoke. I have:

replaced the fuel and both fuel filters,
replaced all the washers on the fuel lines and checked for leaks,
taken the injectors to a shop to be checked.

Now, I don't know what to look at next. Any ideas out there?

Thanks,

-- Tom.

The unpleasant case of the haunted yanmar
 

Thanks Larry. I've looked really hard for air leaks and fuel leaks...
The fuel tank is higher than the engine and I have bled the thing very
well. I'll look some more, but don't understand why it would get
better when it gets warm... Also, if the engine has been wamed up
sometimes it doesn't have the problem the next day... If it was the
injection pump would it ever run well?

-- Tom.

The unpleasant case of the haunted yanmar
 

Could also be water in the fuel.
Check the sump portion of the fuel filters for evidence of free water
..... then be sure to wet the filter cartridge O-rings/seals with fuel
when you reseal them - a possible source of bubbles in Larry's posting.

Flat seals on filter cartridge housings are notorious 'leakers' and
must be installed 'wetted' with fuel oil so that you insure that they
seal.


In article .com,
" wrote:

Thanks Larry. I've looked really hard for air leaks and fuel leaks...
The fuel tank is higher than the engine and I have bled the thing very
well. I'll look some more, but don't understand why it would get
better when it gets warm... Also, if the engine has been wamed up
sometimes it doesn't have the problem the next day... If it was the
injection pump would it ever run well?

-- Tom.

The unpleasant case of the haunted yanmar
 

" wrote in
oups.com:

Thanks Larry. I've looked really hard for air leaks and fuel leaks...
The fuel tank is higher than the engine and I have bled the thing very
well. I'll look some more, but don't understand why it would get
better when it gets warm... Also, if the engine has been wamed up
sometimes it doesn't have the problem the next day... If it was the
injection pump would it ever run well?

-- Tom.



As things heat up they get bigger, sealing the hole, probably. If your
fuel tank is higher, gravity pressure should make it so there's no vacuum
in the whole system...so there should be no bubbles, only diesel fuel
leaking into the hull. Hmm....might be more of injection pump problems.

Has anyone done a compression test on it? How many hours are on it??

The unpleasant case of the haunted yanmar
 

Rich Hampel wrote in news:290320062253232580%RhmpL33
@nospam.net:

Flat seals on filter cartridge housings are notorious 'leakers' and
must be installed 'wetted' with fuel oil so that you insure that they
seal.


I'd have been with this all the way, but he's not pulling a vacuum on the
tank as the tank is higher than the engine. If the gasket were leaking,
his bilge would have fuel in it.

I'd like to see that water test, too. Way too many boaters are too eager
to get back to the dock with guests and leave the poor thing sitting there
with half-empty tanks to breathe the water in every night. They don't want
to be bothered buying 8 gallons of fuel, so the tanks get to breathe and
the problem starts. It's so easy to prevent water in the tanks. It's not
in the fuel you buy at all.

The unpleasant case of the haunted yanmar
 

Regarding air leaks:

I had a impossible to find air leak, which I could not detectable. Over a
period of a year I went over every aspect of the engine with out success. I
finally took apart the fuel line going into and exiting the fuel filters
(frams). I took apart the couplings for the water and fuel filter units. I
reinstalled everything using Teflon tape on all threads. My problem went
away.

stu



wrote in message
oups.com...
Dearest engine wonks,

I have a yanmar 2gm20f with sd20. When it's cold and it comes under
load (eg. the alternator starts developing more than 20 amps) it is
unable to hold its rpms. Typically it runs easily up to speed but then
as the load kicks in it drops back down to idle and then revs back up
past the throttle setting and then drops back down again. Sometimes is
stalls. Once it has gotten warm it runs like a top. There is no
visible smoke. I have:

replaced the fuel and both fuel filters,
replaced all the washers on the fuel lines and checked for leaks,
taken the injectors to a shop to be checked.

Now, I don't know what to look at next. Any ideas out there?

Thanks,

-- Tom.

The unpleasant case of the haunted yanmar
 

On Thu, 30 Mar 2006 08:54:32 -0600, "West Indies"
wrote:

I took apart the couplings for the water and fuel filter units. I
reinstalled everything using Teflon tape on all threads. My problem went
away.

Unfortunately teflon tape has a reputation for degrading over time
when in contact with diesel fuel. Professional mechanics use a
special blue paste to seal fuel fittings.

The unpleasant case of the haunted yanmar
 

I took apart the couplings for the water and fuel filter units. I
reinstalled everything using Teflon tape on all threads. My problem went
away.


There can be air leaks in other places than threaded joints.


Wayne.B wrote:
Unfortunately teflon tape has a reputation for degrading over time
when in contact with diesel fuel. Professional mechanics use a
special blue paste to seal fuel fittings.


IIRC there is tape rated for use with various petrochemicals
& solvents... a bigger problem is that little shreds of tape
get in the injection system. Not good.

Fresh Breezes- Doug King

The unpleasant case of the haunted yanmar
 

I haven't done a compression test on it. It puts out full power as far
as I can see -- its a catamaran and the identical engine on the other
w/identical prop doesn't do any better power wise at WOT. Have this
vague idea that it might be a tiny leak in the water jacket but there
is no obvious steam and it doesn't blow water out of the reservoir. It
has about 1200 hours. We cruise in the South Pacific full time so we
take awful fuel and often run the tanks pretty low on passages.
However, the fuel that is in there now is New Zealand fuel and I took
it all out and ran it through a double filter set-up so I'm thinking
its pretty dry...

In my search for leaks I have pulled the engine out and painted it and
cleaned the bilge to surgical standards. I'm pretty sure that no
significant fuel leaks into the boat... If we're leaking into the
crank oil it isn't raising the level noticeablely...

Many thanks to all for the thoughts -- I'm looking at each carefully
and even running the engine as I type.

-- Tom.

The unpleasant case of the haunted yanmar
 

" wrote in
oups.com:

If we're leaking into the
crank oil it isn't raising the level noticeablely...



The old 4-108 Lionheart came with had like 9000 hours on it and little
maintenance. There was a good bit of unburned diesel oil leaking past
the worn-out rings, but it just ran and ran. The current engine was a
pullout from a nice fellow (who may be watching this...(c;) in Oriental,
NC. I met him on this newsgroup and my captain/owner bought the
engine/transmission from him for $1200, I think. Lionheart's original
transmission is the hydraulic one that can freewheel forever because
Lionheart has a shaft alternator producing 15-20A of charging current at
8-10 knots off her fixed screw. The more recent transmission was not, so
the engine ship switched them. The old engine is in Marietta, GA, in the
captain's garage, last I knew. He was going to rebuild it, but hasn't.

They're great engines. Ours flooded 3 of 4 cylinders with seawater
between Ft Lauderdale and Ponce Inlet to Daytona when it was locked up,
solid. Towed the long way to Daytona Marina up the ditch, Cutter Doc was
hired to fix it and he came that night to pump the Exxon Valdez oil slick
out of the Perkins' bilge. It had tar balls in it! One injector mount
was cracked and 2 injectors were trashed. We changed the oil a "few
times" until pumping it out looked something like oil, then reinstalled
the injectors and she cranked right up. It's been running flawlessly
ever since. The new engine had nicer controls and working guages, too.
We can even read oil pressure and water temperature, now...(c;

Reliable old tractor engine....English like my captain!

The unpleasant case of the haunted yanmar
 

Geeze, I've spent more than that on parts for this sucker and it only
has two cylinders and 1200 hours... If I cut the decks off and took
out two structural bulkheads, removed the galley and shower and removed
a lot of weight from the boat so it wouldn't sink (no problem there,
I'm pretty sure the better half would leave somewhere between deck and
galley removal and take all her stuff) I could install some 4-108's
where my little 2gm20's are. This would solve the hunting problem...
Thanks for the thoughts Larry,

-- Tom.

The unpleasant case of the haunted yanmar
 

" wrote in
ups.com:

I'm pretty sure the better half would leave somewhere between deck and
galley removal and take all her stuff) I could install some 4-108's
where my little 2gm20's are. This would solve the hunting problem...
Thanks for the thoughts Larry,



The old boat, now called "Stray Dog", has a 2GM20 in it. When I took
that one over it kept loosing the closed loop coolant. The Japanese
geniuses hooked the recovery hose to the CAP of the recovery jug, a
separate plastic jug mounted on the bulkhead by the engine. Noone ever
looked inside the heat exchanger. They saw the level in the jug and
everything was fine...WRONG. Stupid design. The pickup hose INSIDE the
jug from the bottom of the tank to the cap had fallen off...allowing the
poor engine to suck AIR not coolant every time it cooled off! The heat
exchanger was nearly dry!

I dumped the stupid design and bought a universal replacement bottle with
the hose properly located out the BOTTOM of the jug from Autozone (geez,
don't tell anyone at the yacht club bar!) and that solved the coolant
leakage problem. I suppose it's cheaper to put the recovery hose in the
cheap plastic cap than have to mold the jug with a built in pipe coming
out the bottom....What WERE they thinking?!

Only other problem it had was caused by the stupid mounting of the 2-
cylinder freon pump for the cold plate in the ice box. It was on a
bracket welded to the baseplate, not the block. So, every time this big
compressor kicks in, it jerks the belt and pulls the engine sideways
against the poor mounting bushings, which were screwed when I got it.
New engine mounts were OK, but I never like to have belts pulling against
rubber mounts misaligning the engine with the shaft as it ages.

Got room in there for the 4-108? It would never have fit in the
Endeavour 35 behind the steps into the cockpit. Would have been fine if
noone complained about the front cylinder and belt-driven stuff sticking
into the galley, though...(c;

The Amel Sharki's engine room is plenty large, but the hatch, the deck of
the cockpit, doesn't extend forward enough to service the front of the
engine where the fragile impeller and belts are located. You have to
climb down into this neck-high trunk in the port lazerette, then bend in
half to get through the little hatch into the port side of the
engineroom. The hot water heater was in the way, so we moved it deep
into the lazarette. I don't see how anyone tightened the belts where it
was...which probably explains why they were all loose and cracked and
burned when we got the boat home from Florida. The steps in the galley
don't come off with a handy hatch dead right in front of the engine like
the old boat. It's not one of the watertight bulkheads, of which the
Amel has 3, so there was no reason not to make one there except you'd
have to keep the down-sliding hatch up to use it. The emergency hand
bilge pump is built into the step so it can be operated from the galley
or cockpit, but I'd rather have the engine room hatch....go figure.

Check that hose in the coolant recovery bottle....often. There's no
indication it has no coolant in the heat exchanger until something bad
happens...as it overheats.

The unpleasant case of the haunted yanmar
 

In article ,
Wayne.B wrote:

On Thu, 30 Mar 2006 08:54:32 -0600, "West Indies"
wrote:

I took apart the couplings for the water and fuel filter units. I
reinstalled everything using Teflon tape on all threads. My problem went
away.

Unfortunately teflon tape has a reputation for degrading over time
when in contact with diesel fuel. Professional mechanics use a
special blue paste to seal fuel fittings.

I'm thinking a leak like this, as well. Perhaps simply reseating all the
connections -- don't overtorque -- might find the problem. I'd also look
to the bleeding valves, all three on the 2GM20F. New "wetted" gasket on
the primary filter (on the engine) might solve it.

That type of surging usually points to an air leak, one too small for
diesel.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

The unpleasant case of the haunted yanmar
 

I have removed all the fuel lines and the primary filter and replaced
the washers and gaskets and retorqued the lines. If there is a leak
I'm not sure what to test next. I am wondering if maybe the governor's
injection limiter setting is wrong. The manual makes it look easy to
adjust, but I'm guessing that they seal them at the factory for a
reason... Any thoughts on the advisability of fiddling with it or with
the likelihood that it might be the problem?

-- Tom.