Yammer Problems and Black Smoke

[GrahamHO]

Originally Posted by Soulflyer1980

Yes that I know, I just had all three injectors serviced, cleaned and pressure readjusted. All good there. What I am confused with is why number two injector pipe is flee flowing diesel at the disconnected injector. Doesn't matter how much I turn the crankshaft, number two is free flowing and nothing out of one or three.


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Quite likely there is an air lock in the pipes or pump formed when you removed the injectors, and then cranked the motor for what reason I don't know. When its all assembled you need to bleed the system again and all should be good.

It must have worked OK sometime earlier so go back and work out which components have been serviced since then. There is always a cause of a malfunction. If the injector pump wasn't touched and it used to work OK, it should still work OK now.

Also have you checked underwater, your rubber fairing that surrounds the saildrive and is glued onto the hull. They can come loose and drop down forming a very effective water brake. Its happened to me. Then you open the throttle and black smoke comes out the exhaust because the boat is held back.

[GrahamHO]

By the way as I recall. Yanmar cylinders are numbered from the rear forward. Number 1 is at the back.

[Badsanta]

I bought a laser tachometer. Put a piece of reflective tape on the fly wheel and point and shoot. Then compair the number to the tachometer. My numbers didnt match the motor was faster than the tach. Your tach may regester higher than the actual run speed. But at the least you will know the real speed.

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[seasick]

Sounds suspiciously like a bad injector pump component. To test, shut off the raw water into the engine so as not to flood your cylinders for lack of exhaust back pressure. Disconnect the high pressure fuel lines on top of the pump. Place several paper towels and rags on top of the outlet nozzles then crank her over for several fast revolutions with the starter. Compare output quantities of diesel of the three nozzles. If one nozzle produces way more or way less, then you have unscientifically proven that there is stuck plunger in the injector pump. Removing this pump is a chore and there is very little documentation on line or in the manuals on how it is done but I have just done it and can be of some help.

[LeaseOnLife]

If you are questioning your injection pump (cyl # 2), and since the injectors are out:

Remove the pipes connecting the injectors to the pump, mount them in reverse order, have them pointing away from the engine. Mount injectors to the pipes, add some hose for the return lines of the injectors. Mount/hold a clear jar around each injector. Turn engine over with the starter a few times to clear air from the pipes, then watch spray patterns for each injector. Since injectors have been cleaned/rebuild, each injector should spray with a significant "chirp" sound.

Above will also allow you to determine timing: turn crank by hand to determine start of spray which should occur at the timing mark for a specific cylinder.

Safety first: Don't get your skin pierced by diesel from the injectors. Be careful with the diesel vapors too, vent well!

EDIT: seasick was faster, his method is safer (not spraying diesel).

[GrahamHO]

Originally Posted by Badsanta

I bought a laser tachometer. Put a piece of reflective tape on the fly wheel and point and shoot. Then compair the number to the tachometer. My numbers didnt match the motor was faster than the tach. Your tach may regester higher than the actual run speed. But at the least you will know the real speed.

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Some. Yanmar and other makes have a tacho feed from the alternator. The one I had on an earlier motor (and I still have the tacho under the house) could be calibrated to the alternator pulley ratio. I did borrow a laser tach to help calibrate it. That type is notoriously inaccurate but they do tell you the engine is going around. You can make a simple correction chart if you can't calibrate it. For example reads 2500 actually 2000 etc. etc.

My 2GM 20 has a magnetic pickup on the flywheel and seems very accurate.

[Charlie]

Originally Posted by Soulflyer1980

Hey guys I'm still head over heels in my engine bay and trying to figure out what the issue is. Recently I have taken out the whole exhaust system, beginning with manifold over the mixer to the tubes, water lock all the way to the through hull. All as clean as a whistle (black one thought) and nothing is clogged. I have taken out my Injectors and given them to a Bosch service, even though a bit clogged and funky spray pattern the service guys said it couldn't have caused the described problems, if any really apart form a little lack of power.
Now, while undoing the diesel lines at the injectors, I noticed the center one is free flow pissing diesel, nothing out of the other two. I thought that might be because of the 'self bleeding' system or similar and, depending on crankshaft position, one will free flow at a time. So I turned the engine by hand, counterclockwise from stern, but number one or three never piss diesel and number two doesn't stop! What's that all about?


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Could someone with more knowledge correct me if I am wrong.

My understanding of an injection pump is that it injects fuel into cylinder when the piston reaches TDC at the compression stroke. In this case above the fuel is not being injected at the correct time. Too much fuel is going to cylinder 2 and none is going to the others. Excessive fuel will produce smoke. I don't understand how the engine runs without the fuel getting to 2 ot the three cylinders.

Diagnosis: 1) Reassemble injector lines. Start engine. Remove injector line from cylinder 1. Does engine change how it runs. Check for fuel coming out of injector line.

2) Do the same as above for cylinder 3

3) If you are not getting fuel to the two injectors then you are having problems with the IP.


Also could you please comment on the oil level and its viscosity?

[Mikado]

I don't know much about timing the injector pump but I'm pretty sure that on a four stroke engine the fuel needs to be injected into the cylinder on the intake stroke. It needs to have both air and fuel prior to the compression stroke to in order for the compression to generate enough heat to combust he air/fuel mixture.

[a64pilot]

Originally Posted by Mikado

I don't know much about timing the injector pump but I'm pretty sure that on a four stroke engine the fuel needs to be injected into the cylinder on the intake stroke. It needs to have both air and fuel prior to the compression stroke to in order for the compression to generate enough heat to combust he air/fuel mixture.

Not on a Diesel, the fuel begins to burn the moment it is introduced into the compression chamber, that is why injection timing is so important.

You are correct for a spark ignition engine though.

[Mikado]

A64Pilot,

So the only purpose for the intake stroke is to pull in air? Very interesting and good to know. I knew that the injection pump timing was important but assumed it would be more similar to the ignition timing of a gas engine where you could be off a few degrees either way and still run ok.

Thanks,

Jeff

[GrahamHO]

Originally Posted by Mikado

A64Pilot,

So the only purpose for the intake stroke is to pull in air? Very interesting and good to know. I knew that the injection pump timing was important but assumed it would be more similar to the ignition timing of a gas engine where you could be off a few degrees either way and still run ok.

Thanks,

Jeff

Right! A diesel only sucks in air. There is no throttle valve on the air intake. The air is compressed around 20 / 1 The injector in the cylinder head ( where a spark plug would be in a gas engine.) starts injecting a fraction before the top of the compression stroke. The fuel sprayed into the cylinder is ignited as it enters the combustion chamber by the heat generated by compressing the air. The power is varied by changing the amount of fuel supplied from the injector pump. The injection pump is (normally) gear driven with its timing set when the engine is assembled.

( New common rail diesel engines are different in that all the injectors have a constant fuel pressure supplied by an untimed pump. Each injector is opened electronically at the correct time)

On the Yanmar engine in question, if the injection pump has never been removed or disconnected since the time when the motor ran correctly; its timing will not have changed.

I would replace the injectors (using new washers) and bleed the system to start with. If his motor is only running on 1 of the 3 cylinders it will be shaking around and quite obvious. I don't know what he means by fuel pissing out. It should only be a tiny amount on each power stroke.

Also I haven't understood whether it is smoking running both in neutral moored; as well as under way at sea. As I understand, he worked on the sail drive while the engine was removed. Then that unit is only supported by one flexible mount and moving it around could dislodge the under hull rubber fairing. If it drops down there will likely be black smoke under way.

Another very slightly possible reason for black smoke may be an obstruction in the air intake such as a rag placed there to prevent anything dropping in while it was worked on. I've never tried that to see if it causes black smoke but I imagine it would.

[paulajayne]

If the injector washers are copper then heat them until cherry red and allow to cool naturally. They can them be reused. Will say a few pennies.

[Soulflyer1980]

Jeez that is one thing bugging me like crazy!

So far what I have done:

-All three injectors serviced and Injection pressure readjusted (as good as new)
-Intake manifold clear of any obstruction till valve
-Exhaust manifold clear of any obstruction all the way to through hull
-Propeller and Saildrive as clean as they get without anything tangled or causing drag
-Took the Anode of the sail drive and even though propeller is grinding a little, no problem
-Opened the Cone clutch assembly, checked bearings and gears (all 100%ok)
-Checked sail drive rotation (by hand) and compared it to other side (all 99% similar)
-Checked Oil level and viscosity (found diesel in oil, not existing at begin of thread)
disconnected lifting pump and ran diesel line direct to filter, no more diesel in oil (speaks for
a damaged membrane in lifting pump) but original problem still unchanged (low revs and
black smoke under load weather in marina or at sea) Oil brand new now and no more
Diesel diluted!
-Changed all diesel filters on faulty engine (even though quite new before) same problem
-Checked the Injection pump for bumps or other visible spots where timing could have been
accidentally changed (nothing) plus it revs in neutral exactly like the other engine, without
black smoke. I don't think timing is off
-bled the whole diesel system numerous times (and not for the first time) with no change to
the initial problem

While doing all that I found out a funky issue with my Injection pump. I described it earlier but found it might have been misunderstood. With the engine off, I loosened all three injector lines at the top of the injector (my aim was to take the injectors out) after I took all three injector lines of the injector I noticed #2 was free flowing Diesel and nothing out of #1 and #3 (engine is not running!).
My first thought was that the injection pump was positioned in a way to cause the free flow out of #2. So i turned the engine by hand to see if that will change and each diesel line will, one at a time, free flow some diesel. In my head I thought this could be from the automatic bleeding system. But no, I can see #1 and #3 "injecting' at their 14 degree after TDC and #2 as well but all the time number 2 is spilling diesel like an open tap.
I called Yanmar without real help, called bosch service and other Injection pump specialists all with the same answer "Impossible for the diesel to free flow out of injection lines"...now i am stunned. All I know it is free flowing and not stopping.

Does anyone had or heard of that issue before? I can make a video if necessary.

Thanks

Ferdinand

[GrahamHO]

You have certainly gone over all the obvious possibilities. Diesel would free flow out of the return line but I'm sure you are aware of that.

[Bluebeard]

Ferdinand,

two things don't sound right to me, the continous free flow from no2 and the timing. I will say that I'm no expert, but :-

try disconnecting the injector lines from your good engine and see if the same thing happens. If it behaves as you would expect, ie fuel flows only at one point in the cycle from each line then it points to a problem in the pump.

An injection point 14 degrees AFTER TDC doesn't sound right. The parallel with a petrol engine is that if the ignition was that far retarded then the engine would be low in power and not pull. The air in the cylinder will be hottest at tdc so I would expect the injection to start round about then.
Could it have been reinstalled one tooth out? Have you been able to confirm that this is the right timing?

Ian