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Yanmar
SB12: Running the Engine
This page was last
updated
on 10 July 2001
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After much
preparation, the time came a few weeks before launch to test-run the
engine. I had a few final things to do before attempting a startup.
First, I checked all the fuel connections, and replaced the secondary fuel
filter with a new element. I checked the engine mounts to ensure their
tightness, and removed the suction side of the intake hose from the raw water
pump, replacing it with a length of hose long enough to run into a 5 gallon
bucket of water. I ran a garden hose with a valve at the end to the bucket so I
could add more water as necessary. Then, I added 5 gallons of diesel fuel to the
fuel tank, and checked all connections again. Using the outboard primer
bulb I installed in the fuel system, I primed the fuel system and bled the
lines, at least as much as possible at that point. I connected my starter
battery to the cables that I installed over the winter--just a ground and the
starter feed for now. As I tried a test-start just to check the electrical
connections, I realized that I had neglected to run the power feed to the gauge
panel--duh. I connected the ground wire to the negative distribution buss,
and the positive directly to the battery for now. Success! The
starter cranked right over.
After a final
check of everything, I prepared for a real test run. With the throttle
advanced, the engine started almost immediately. At first, I wasn't sure
it was drawing in cooling water, so I shut down to check everything. All
OK, so I restarted the engine, and after a moment it settled down to a
reasonable roar. The engine ran fine for a few minutes before beginning to
die, apparently signifying air in the fuel system--a common issue, and not
surprising considering that the fuel system was entirely new, had never been
primed, and the engine hadn't been run for well over a year.
Several bleeds of
various areas did not allow the engine to start, and I have found significant
air in the secondary filter housing, which filter I changed just before the
initial start. I think this is the problem, and will continue bleeding
until the beast starts again. All it takes is a little air to cause this
problem, so I am confident that there is nothing more significant wrong.
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 After
more attempts at bleeding, there were still no positive results. For those
of you who may be interested in the diagnostic process, I have included the
drawing from my shop manual. It shows an exploded view of the high
pressure injection pump. Also, click on this the thumbnail to the left for
a labeled photo of the actual arrangement.
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 After installing the new pump, and rebleeding
the whole system again, still no luck. Smitty admits to being baffled--he
said he's never been stumped by a one-lunger before. He took apart the injection
pump, and all parts seemed to be working properly. Then, he took the pump
into a local shop that specialized in diesel fuel injection, and had the pump
tested--OK. His latest thinking is that maybe there's something fishy
going on with the governor/throttle system. That's where he will focus his
attention when he returns today (Saturday, 5/12).
UPDATE 5/14:
No luck yet. After reassembling the pump,
Smitty noted while I was cranking the engine that the gasket beneath was seeping
fuel--and thus air. He had been afraid of the condition of the gasket all
along, but hoped to eek it out for testing purposes. Not! That
basically shut us down while we wait for parts--I ordered parts to rebuild the
existing injection pump, then also went ahead and ordered an entire new
assembly. Of course, nearly all the
parts we ordered aren't available overnight as we had hoped--instead, they will
ship after a couple days, so they won't arrive here at best until Thursday the
17th--launching day! We're going to go ahead with launching no matter
what, and deal with the engine afterwards. Work can be done just as easily
with the boat in the water.
UPDATE 5/26:
The engine runs! Finally, after
frustrating delays waiting for parts, we received the new fuel injection pump
and installed it. The engine started almost immediately. When
comparing the two pumps--the old and the new--it was obvious that the old was
bad--the piston was all loose and sloppy, while the new one was clean and tight.
The old pump will be rebuilt with new parts for a spare--seems like it might be
good to have a large inventory of spare parts for this engine, particularly the
inexpensive ones that we can afford to stock. Nothing would be more
frustrating than more of these ordering delays if we really need a part down the
road--or worse, complete unavailability of a certain part!
The engine sounds good and is smoother and
quieter than I expected...but it does vibrate a lot, and engine room insulation
will be a priority for those long days motoring if there's no wind.
Soundproofing material is already on hand--I ordered it months ago, but never
had a chance to get it installed. I hope to install it within the next few
weeks, prior to a planned two-week cruise in July.
We have a little fine tuning to do with the
throttle and governor system, but other than that, we're in business. I
even got the engine gearshift hooked up, finally! (Details on that here)
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UPDATE 6/1:
After a marathon, four-hour session, Smitty
and I seem to have the throttle action and governor adjusted to a place we can
live with. The problem before was that there was a lot of throttle
creep--that is, when you advanced the lever, the springs on the governor
assembly would pull it annoyingly back. Also, the idle speed was too low
when the throttle lever was pulled all the way back--in fact, the engine would
shut down. I wanted to be sure that dead idle speed would be high enough
to allow shifting without a problem, and we will shut the engine down with a
previously installed cable attached to the decompression lever.
The fuel adjustment and governor assembly is
like nothing Smitty (or I) had ever seen. I marveled at his patience as he
fussed with the thing--there is literally about 1/16" difference between
full fuel and no fuel on the needle valve at the fuel injection pump. This
makes adjustment extremely difficult, if not impossible. However, during
those four hours, Smitty made good progress with the adjustment, and eventually
we got things adjusted out so that now we can make minor adjustments with the
idle speed screw, as intended--before, when the engine was at a suitable idle
speed, there was about a 1" gap to the idle screw when it was maxed
out. I don't know how he didn't throw something overboard in frustration
during this process--but I'll bet he wanted to!
Things seem to be adjusted properly at the
moment. The next step is a test with the engine under load--that is, in
use. We couldn't do it after the adjusting session because it was nearly
9PM when all was said and done, and the launch service ends at 9. Plus, it
was dark out, or nearly so. I will take the boat out soon and check the
engine's operation when the gear is clutched in and report back.
FIRST
ENGINE USE 6/1/01 Well, I took the boat off the mooring under
her own power for the first time. There's still some fine tuning to
do. The throttle creep is a real problem--the throttle just won't stay at
the proper setting where I want it. I think we'll add a return spring to
hold things in place. I don't have gauges hooked up yet, so I don't know
what RPM I was turning. However, I was able to achieve over 5.5 knots,
with room to spare before WOT. At just over idle speed--the spot where the
throttle lever always seems to end up--I got around 3-3.5 knots, according to my
knotmeter and GPS. Perfectly acceptable.
The engine smokes a lot. I hope this is
going to stop eventually--it's embarrassing, and stinky. Also, there is
apparently a lot of combustible material on the engine block itself, as the
engine room gets smoky. There's probably plenty of diesel residue left
over from all that bleeding, which made a real mess of things. It's been
cleaned up, of course, but the residue is there to slowly smolder.
Hopefully, that will stop, too--a cabin full of smoke is no treat.
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 After
a short run outside the anchorage, I returned to my mooring. I went below
to open the engine room and look at things (with the engine running), and, much
to my surprise, there was water running everywhere, particularly on top of my
new starter. Cool. I shut down, and looked for the source. At
first, it looked like it was coming from the engine exhaust hose somewhere, but
it was not; it was only running down the hose because it was close by. The
leak (not a leak so much as a true gushing) was coming from a fitting on the
port side of the engine, just above the starter. (That's it in the photo, just
above the belt in the foreground...) After consulting my parts manual, I
determined that this is a drain fitting, and the fitting had opened because of
the vibration of the engine. There's a nut on the end that I tightened to
stop the flow. There is supposed to be a drain hose attached to the
fitting, and I guess it's used to help drain the engine for winterizing.
It was only indicated by name on one page of my parts manual, so it took me some
time to actually figure out what it really was.
Don't ever let anyone tell you that
commissioning a new boat (or one that is, for all intents and purposes, new,
even if it's old...) is easy--there are so many things to overlook, and
therefore to go wrong. We are really closing in on it, however--for now,
we'll take it slow and easy, and get everything worked out in short order.
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The engine doesn't pump that much water,
either. This makes for a noisy exhaust note, and it's a little
disconcerting. I'd be happier to see more water coming out the
exhaust. I have to check into this--I know the pump works. Perhaps
the need of the engine is just so low, that it takes a while to fill up the
waterlift chamber--which has to happen before back pressure ejects the water out
the transom. Definitely still a few things to check out...but I think it
will all be OK in the end.
UPDATE 6/8/01
So, the fun continues. The white smoke and
lack or exhaust water are two major concerns. From my own research, I
determined that white smoke is generally caused by one of four
things:
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Cracked block or head, allowing coolant
(seawater) to enter combustion chamber
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Blown head gasket, which would also allow
coolant to enter the combustion chamber
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Improper combustion, caused by bad fuel,
water in the fuel, or improper injection
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Fuel in the lubricating oil
Of the list, obviously #1 and #2 are less
likely than #3 or #4. However, I had heard from a friend with past
experience that these engines tend to blow head gaskets. So, I ordered a
couple to have on hand regardless. The cracked block syndrome is far less
likely--I mean, the engine runs like a top, except for the exhaust smoke.
Smitty's guess: fuel in the oil. First step: change the oil,
which was on my list anyway. The thought was that fuel had been
leaking down through the mechanical side of the injection pump before the new
one was installed, so it probably had diluted and contaminated the lube
oil. After changing the oil, however, there was no real change.
Also, Smitty noticed afterwards that there was pressure in the oil pan--oil
sprayed out the dipstick hole when the dipstick was removed with the engine
running. There should be a slight vacuum. No harm in trying the simplest
fix first, of course, and the oil needed a changing anyway.
Next thought: pull the injector nozzle
and have it pop tested. Removal was a fairly simple task, and the nozzle
was out in a few minutes. The next day, I ran over to a local diesel
injection specialist, and for $8.00 they tested the injector for me.
Results: excellent. Scratch that off the list.
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 With the injector removed, and the top end of
the engine already partially disassembled, we decided to go for it, and remove
the head to replace the gasket. The first thing Smitty did was remove the
starter, so he could set the engine at top dead center and ensure that the
timing was on. This involved removing the alternator for  better
access, then unbolting the starter housing to expose the flywheel behind.
After lining up the timing marks, off came the bonnet--a simple matter,
really. This exposed the remaining two head bolts. That was it for
the evening, as it was nearly 9PM.
The next night we were right back at it.
In about 2 seconds, Smitty had the head off. All in all, it seemed to be
in pretty good condition. (I forgot my camera this night, so no pictures
of the disassembly--sorry!). There were no signs of cracking, but one of
the cooling passages for raw water was completely plugged up. The gasket
looked a little tough, but it was hard to tell, since it was torn apart somewhat
by removing the head. It looked like there was one area that was
definitely not right, though, so that seemed to make the job worthwhile.
The valves, combustion chamber, and piston all looked to be in good condition;
rotating the crankshaft a little lowered the piston (by the way, the timing
marks are right on, as the piston was indeed at TDC when the head was removed), allowing
us to check out the cylinder walls. Generally OK, which was good news.
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After cleaning off the old gasket from both
sides--a time consuming process--the new gasket was installed, and the head
reattached. That was it for that night, as we had to order some additional
gaskets in order to reassemble the exhaust system. The thermostat looked a
little suspect too, which might be accounting for the lack of cooling water out
the exhaust.
UPDATE 6/17/01
After a few delays, we finally got the top end
of the engine back together. In the process, the valves were readjusted
back to factory clearance, and we checked the engine timing--it was off about
two degrees, so Smitty removed a little shim from beneath the fuel injection
pump. This is how injection timing of adjusted on this engine, and
removing the shim changes timing by 2 degrees. Right on!
With the exhaust system reassembled, and a new
thermostat installed, we had high hopes when we cranked the engine. There
was still some smoke, but it seemed to be maybe a little less intense than
before. However, there was virtually no cooling water coming from the exhaust
outlet--there really hadn't been all along through this whole process, a real
concern of mine. The good news, however, was that the engine ran like a
top--smoother than before, quiet, and generally being a real trouper.
The next step was diagnosis of the cooling
system. All parts were checked, beginning with the obvious--the strainer
and raw water pump--and moving upstream from there. The pump seemed to be
operating fine, and has a new impeller that I installed earlier this year.
Why wasn't there any cooling water?
After removing the exhaust silencer and
thermostat housing again, Smitty finally found the likely culprit--the main cooing
water passage through the silencer was blocked so badly that neither of us had
even noticed it was supposed to be there, despite repeated inspections of the
housing. It was plugged solid. It was cleaned out, and the housing
reassembled. Success! Finally, the exhaust belched some black, nasty
water, and continued purging in the expected bursts from the waterlift exhaust
system. This was good news, finally. The exhaust note, which had
sounded like we had a cherry bomb installed, was smooth and quiet.
We ran the engine for a time the next day, and
the white smoke seemed to dissipate after a while. Given the color of the
exhaust water, it definitely seems that the engine has to burn through and purge
some junk from within, so we can deal with a small amount of smoke. Except
for throttle creep, the engine pushed the boat successfully, and sounded
great--smooth and relatively quiet. Later, I intend to install engine room
insulation, which should really shut things up.
Next: giving the engine a good, long,
hard run under load to try and burn things off and clean it out. Click here
for details of the test.
UPDATE 7/10/01
Lack of satisfaction with the engine
continues. In the weeks since replacing the head gasket, we have used the
engine minimally because of excessive smoking at all speeds. This causes embarrassment--we
seem to have our own personal fog bank following us at all times. It's
obvious that the engine is in need of a real rebuild--top and bottom ends--rings
at the very least. This is not something we are interested in or inclined
to do--while the engine might turn out fine afterwards, I can't see putting any
more time and effort into a nearly 30-year old engine that may or may not be
properly suited to the boat. Chalk this whole experience up to lessons
learned, cut losses, and move on!
The throttle creep has not yet been addressed,
and is a real pain. Obviously, this is not a factor in our decision to
replace the engine, but it has made using the current engine less enjoyable.
Initially, I thought the engine would be OK to
get us through the remainder of the season. It's OK for getting on and off
the mooring when necessary--we usually sail in and out anyway--and for those
occasional trips to the dock for cleaning, etc. The smoke is a major
problem, however--one that we can't accept. It's become bad enough that I
don't think we can hold out for the season. We're looking at replacement
(NEW) engines now.
At the time we bought the used engine, it
seemed to be the right thing to do. That was in December 1999, only a few
months after we first purchased the boat. The boat was still a horror
show, in the midst of a deck recore and interior gutting. As a reminder,
here are some photos from around that time, showing the general condition of the
boat:
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At that stage of the game, we had barely
gotten started. Even though I had my vision for the completed boat, I had
no idea how far I would take the restoration. As time went on, I ended up
deciding again and again to replace old gear and such with new. We jumped
at a seemingly decent engine when it became available, as finding a decent (ha!)
used diesel is definitely not the easiest thing to do. I figured that,
when one that seemed a likely candidate came up, we had better be ready to move
on it. I definitely wanted the engine decision made earlier rather than
later, since I needed it before I could begin reconstructing the interior.
Maybe, if we had waited a little longer, it would have become more apparent that
something new would be more desirable. Hindsight is 20/20, as
always. However, mistake as it has turned out to be, I stand my ground and
announce that at the time, under the circumstances, purchasing the used diesel
was the right thing to do. There's no point in dwelling on the past;
rather, it's time to move forward and make the boat entirely what we want her to
be: a well equipped, capable coastal cruiser with longer-term cruising
aspirations. This requires solid structure (done), comfortable
accommodations (done), good sails and rigging (done), excellent systems (done),
and a reliable engine capable of powering the boat through slop and current
while providing alternator charging power for the ship's batteries (oops--we
failed here!). All in all, not a bad track record.
Lessons learned:
1. Any used engine you might purchase
should be torn down, inspected and/or rebuilt, unless there is reliable
documentation to the effect that it has already and recently been done.
2. If you're considering a used diesel,
reconsider--unless you're a gearhead who wants the challenge and inherent
project in rebuilding the engine yourself. This could be a satisfying and
fun project. Maybe I'll even consider doing it to the SB12 if I can't find
anyone to buy it.
3. I would still prefer a diesel over
even a newly rebuilt Atomic 4.
4. Obviously, it would have been nice to
have had the engine epiphany at an earlier stage in the project. However,
replacement now should be relatively simple, as I have built in good engine room
access.
That's it for this page. New engine
updates will be posted here from now on.
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