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Old 19-01-2010, 11:53   #1
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Yanmar Smoking and Making Oil

After 5 solid months of 10-12 hour days getting a huge refit completed, my wife and 2 kids and I cast off the dock lines yesterday around noon and motored off from Ortega Yacht Club Marina in Jacksonville with plans to head outside south to Cape Canaveral.

We didn't get very far!!

Part of the refit work I just did involved taking most of the ancillary parts off of my Yanmar 4JH2-HTE so the engine could be stripped, cleaned, primed and repainted. A couple of years ago before I purchased the boat a raw water hose got loose at the back of the engine and hosed salt water over the backside of the engine. The prior owner rinsed it off... but it still resulted in a fair bit of surface rust all over the back of the engine. I took everything off to properly remove all this and repaint the engine and in general clean up the entire engine room (btw, it looks great now!)

I had the turbo off during this and I cleaned it out with carb cleaner and rinsed it with hot water plus compressed air. The turbine blades spun freely.

I also had the injector pipes off so I could reach the block and repaint everything. I did seal up all of the ports in the head and injector pump to prevent and dirt ingress.

The engine has given off some light grey colored smoke in the past, not excessive but noticable. Last Christmas in St. Thomas I had the Yanmar dealer "service" the injectors and engine. They adjusted the valves and set the injector pressure and cleaned the injectors but they did not install any new injector parts or such.

The smoke we saw yesterday was much darker in color, a definite dark blue to blackish smoke. Not pitch black, but darker. Also, there rapidly showed a fair amount of black soot across the transom something that has never appeared before.

I checked and noted the oil level before leaving, it was just slightly over the full mark. When I checked it after anchoring, it was a good 1/2" above that point and the oil feels and looks diluted with diesel.

The engine fires right up when started. It does not spin overly fast at startup and it never turns over more than 4-5 times before firing off even when cold and it usually first on the 3d turn. The engine has always run well and yesterday it ran pretty much as normal.

This morning after checking the oil and determining for sure that the oil did appear diluted with diesel (no sign of water at all) I decided to seek professional help. I called around and now we are tied up alongside a barge at JAcksonville Boat Works just in from the inlet on the St. Johns. I did change the engine oil this morning before motoring up here.

The guys here have removed the injectors and sent them out to be tested and to have new nozzles (which I had in the spares inventory) installed. When the techs were inspecting the engine while running, they cracked the fuel lines open at the injectors to see how it impacted the engine running, to get a read on compression I believe. On two of the cylinders it had a big impact on the running and on the other two a lesser impact. The engine idled this morning as if it were dead on one cylinder. Two of the injectors were very sooted up and nasty when they came out.

I am more than just a tad worried! A major engine compression issue at this point would be a disaster. So.... what do folks think?


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Old 19-01-2010, 13:07   #2
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Cracking the injectors one at a time is to determine if the injector itself is operating, not to determine compression. If all four injectors are operating properly as each one has it's fuel line opened the engine should falter. If the engine falters it is the first sign that the injector is good. If it does not falter it is the first sign that the injector is having trouble. Hard to trouble shoot a diesel over the internet but from what you describe you have two injectors that are giving you fits. That would certainly give you the black smoke problems you described.
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Old 19-01-2010, 14:04   #3
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At first glance, I would suspect the fuel lift pump.

You don't get a "Read" on compression by killing a cylinder one at a time.
All you determine is a non-firing cylinder.

If you had a "dribbling" injector you may see smoke and/or fuel sheen on the water. you have a mechanical lift pump or electric fuel pump
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Old 19-01-2010, 14:14   #4
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In threes...

On the theory that troubles come in threes it's possible that you have several things wrong with the engine.

On the diesel in the oil I'd agree with the lift pump being the likely culprit and look at a new lift pump (or however Yanmar fix their lift pumps). I agree that the injectors are the likely culprit for the smoke.

Have you replaced the raw water impeller? Changed the transmission oil?
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Old 19-01-2010, 14:46   #5
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Lift pump is mechanical, a very small little pump with a finger activated pump action that can prime the main pump if there is significant air in the system. I never use it. We installed a Filter Boss dual filter system with an electric pump and when bleeding the injectors during re-assembly of everything the electric pump at the Filter Boss did the trick.

During normal running we do not turn this electric pump on. It was not turned on at all yesterday nor today.

How would this lift pump be getting fuel into the oil?

The raw water impeller was replaced last summer and was recently checked, still like new. The transmission oil was also replaced last summer with less than 100 hours since.

The guys working on the engine seemed to think it was dropping a cylinder at idle and they disconnected each injector in turn in an effort to try and determine which cylinder may be dead. However, as each injector was cracked open the engine clearly lost rpm though less so on 2 cylinders than on the other 2.

We are not going to hear back from the shop doing the injectors until tomorrow, we sleep tonight side tied to a commercial barge... yipeee !

I speculate that one or more injectors is drippling resulting in fuel flowing past the rings and diluting the oil thus raising the oil level resulting in oil getting burned and thus more smoke?

Or rings are bad and I am screwed.

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Old 19-01-2010, 15:17   #6
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Guaranteed this is a bad lift pump diaphragm, which is slowly pumping fuel into the crankcase as its also pumping fuel up to the injector pump. We see this all the time with Yanmars. Either change the lift pump or replace the diaphragm.

For the skeptics, here is the scenerio. The lift pump is activated by a cam that is pushed from the crankshaft. It is installed down low on the block, in an opening over the oil sump. The cam is pushing against a metal disk that is pushing against a rubber diaphragm. On the other side of the diaphragm is the fuel that is pushed or "lifted" on to the injector pump. When a small hole is in the rubber diaphragm, some of the fuel runs out on the crankcase side, even though the pump still generates enough pressure to move fuel on up stream.

Eventually, the oil sump is way over filled, and the motor starts to drown in fuel/oil.

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Old 19-01-2010, 17:59   #7
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Would the sort of lift pump diaphragm failure you describe cause the kind of soot buildup on the transom and the bluish/grey smoke? We pulled one of the turbo hoses going to the intake manifold off and found no oil, if the crankcase was being filled to the point where oil/fuel was being pushed out the breather into the intake manifold would we not have seen it there? I can see how a lift pump failure would allow fuel into the crankcase but where/how would it end up being burned to generate the soot and smoke?

Whats the best way to test for this?

Is the lift pump in fact the little pump with the external finger activated pump lever to allow manual operation or is this something different?

The manual for this engine makes no mention at all of any such possible failure.

EDIT: No way its lift pump related, the lift pump on a 4JH2-HTE Yanmar is activated by a cam in the injection pump and is mounted on the side of the injection pump. It is not connected to any engine oil supply in any way, no fuel leak at this pump could find its way into the engine oil.

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Old 19-01-2010, 18:21   #8
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does the injecto pumpr share oil with the crankcase? or have its own supply?
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Old 19-01-2010, 18:30   #9
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I would lay money on the small fuel transfer pump (finger-activated pump). Just had to replace both on each Yanmar engine on our catamaran within two days of one another. Same symptoms - stuttering and blowing smoke. Bring the RPM's down and the problem seemed to go away. Building fluid in the crankcase which was deisel fuel. The internal diaphragm in the pump separates the deisel fuel from the crankcase. If you open the fuel transfer pump and look very closely, I suspect you will find a hairline crack about 1/4" long. Change out the fuel pump as the problem will only get worse.
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Old 19-01-2010, 18:41   #10
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I looked closely at the engine. The lift pump bolts to the side of the injection pump, not the engine block. But the injection pump would appear to share engine oil with the engine and thus I believe a leaking lift pump would allow fuel into the engine oil.

It appears easy to access and remove.... I will do this in the morning while waiting to hear from the injector guys. I also think I have a spare lift pump on board.

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Old 20-01-2010, 14:11   #11
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Its not good...

The injector shop said that one injector was a real mess with 2 of the holes totally plugged and the others bad and they said this one would have dribbled fuel. They also said one other was bad and the other 2 were not so hot. The nozzles were all replaced with new, the injectors rebuilt and then properly setup on the bench at a professional marine injector shop. They came back looking like brand new.

I also installed the new fuel lift pump I had in spares. The old one was clearly old, probably original to the engine (1992). I took it apart and while the diaphragm did not look great it did not show any obvious cracks or places where it would clearly leak from.

So, new injectors and a new lift pump. We fire the engine up and it seems there is a bit less smoke. We let it warm up at fast idle and then with a falling tide we decide to head out. I settled the bill with the yard ($750 ouch!) and headed out. The head tech had said that since I was at full temp when leaving I should ease it up to full throttle and see what it did under load.

It blew lots of smoke. Very dark smoke, black and lots of it. The engine rev'd and produced power but it definitely was throwing as much black smoke as before. When I backed off to our normal cruise 2400 rpm the smoke turned back to a thick grey color but we were definitely making as much smoke as before.

The boss tech who was watching us depart called me on my cell as they could clearly see we were throwing bad smoke. It was the end of the day and we did not want to spend another night tied to the barge in the boat yard so we agreed to come back first thing in the morning. He wants to look at the turbo and suspects something there is the issue now, he wants to test the boost and use some turbo wash procedure that Yanmar recommends.

After motoring up the river for 30 minutes we anchored up in our old spot and I let the engine sit for 15 minutes before checking the oil. Its hard to say but it appears we may be a little higher on oil than we were when we left. I cannot tell for sure.

So.... any ideas? I really don't have $20K for a new engine.

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Old 20-01-2010, 14:27   #12
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I’ll start with a disclaimer of not being any kind of a diesel mechanic.

That said: I suspect that you damaged the turbo with your cleaning process. Could have contaminated a bearing and it now is dragging or frozen. Without the air boost of the turbo it will run terrifically rich at high speed but should run pretty fair at idle speed.

Enough time running super rich would contaminate and then foul the injectors and would dilute the crankcase oil with the unburned fuel running past the rings.

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Old 20-01-2010, 21:18   #13
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Going back to your cleaning of the turbo.

When you said you used compressed air....did you use the air to "spool up" the turbo? Without the forced lubrication...that is not a good thing to do.
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Old 20-01-2010, 21:39   #14
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Did you change the oil before you ran it?
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Old 21-01-2010, 05:34   #15
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Yes, changed the oil immediatly upon discovering the issue and changed it again after motoring up to the boat yard yesterday.

As to the turbo... the compressed air I used was only from a can, the kind you use to blow off electrical stuff and such. It did not spool up the turbo. The turbo blades would spin freely with your finger rotating 4-5 times with a simply flick of your finger on them. This was after the cleaning, before they would rotate but not as good and there was a fair amount of carbon.

I also removed the exhaust elbow and cleaned it out with wire brush, cleaner and a hose so it is clean and not blocked up.

The techs here are now thinking turbo something or some kind of issue keeping the engine from getting the amount of air it needs.

When I fired her up to motor back up to the boatyard this morning (we anchored out for the night) she fired instantly and seemed to run fine except for all the smoke.

This all has me second guessing whether or not I left a plug or a rag in something I put back together or some silly thing though I cannot imagine doing such a thing.

.... the chase continues as the money flows out.


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