Yanmar Smoking and Making Oil

[Tellie]

Originally Posted by danielgoldberg

Well, I'll tell you one thing, you better figure this problem out and tell us all the cause and solution! I feel like I'm hooked on a daytime soap and I can't wait for the next episode.

Keep your chin up Terry! We're all pulling for you!

179 responses and 5,366 views. This IS getting is addictive.

[Tspringer]

OK....

I disconnected the boost hose that runs from the intake manifold to the injection pump as NM requested. Reviewing the engine manual, this hose feeds boost from the intake manifold to the injection pump boost compensator. As boost increases, it increases the fuel being supplied to the engine (as best I can tell). I removed this hose and fired the engine and let it warm up.

As the engine was warming, there was definite air pulsing out of this hole in the intake manifold. The air pulsed.

When the engine was up to temp, I put it in gear here at the dock. Figuring that the point of the test was to see if not having the boost pressure increase the amount of fuel the injection pump would push would have an impact on the amount of smoke I am getting I determined that it would be best to test with the hole in the intake manifold closed so that the engine was getting all of the turbo boost. Otherwise, lots of boost would be blowing out this hole. So I taped the hole off so air would not blow out. I also disconnected the breather line from the air cleaner so I could look for pulsing air blowing out and smoke or such under load.

Here are the results.

1000 rpm: minor light to medium colored smoke, some air flowing out of the breather line but no pulsing and minor, air at the intake manifold boost hose had a decided pulse to it (was then taped over but the tape cover could be seen to still pulse mildly)

1500 rpm: A bit more smoke, still light to medium grey in color, the same amount of air coming of the breather line and no pulsing or smoke and the tape over the boost outlet on the intake manifold was pulsing more.

1800 rpm: The same amount of smoke and same condition at the breather line, more smoke of about the same color as 1500 rpm but not billowing amounts.

2000 rpm: Breather hose the same, no pulsing and steady pressure on the tape over the boost hose hole on intake manifold, lots more smoke and black in color, also a clear fuel sheen is being left on the water and the exhaust water is black.

2550 rpm.... Max throttle, engine under max load. Billowing black smoke, fuel sheen on water, exhaust water is very sooty, pressure at the boost hole blew the tape off (after I checked the smoke) and when I cut the throttle and shut her down there was a tiny amount of light colored smoke trickling from the open breather line. I did not get a chance to put my finder over the breather line while the engine was at max load.


So... my conclusion would be that the issue is not something wrong with the boost compensator unless it is stuck way beyond its maximum fuel allowable settings or something. The lever on the back of the pump that allows the cutoff of the boost compensator for extreme cold weather start does move back and forth relatively smoothly. The hose itself connecting the intake manifold to the injection pump has no obstructions.

Let me add another confusing bit of info to all this....

It appears the engine may still be making oil. When I last checked the oil with the engine cold several hours after running the oil level was just under the full mark. When I checked it this morning before running.... it was just over the full mark. It is hard to tell for sure, but it is possible I am somehow still diluting the oil with fuel.

I am more and more starting to believe that one cylinder has bad compression, is not burning the fuel thus causing all the black smoke and soot and some of the unburned fuel is running past the rings and diluting the oil. Catastrophic....

Chief Engineer..... after adjusting the prop pitch we ran the engine about 25 minutes, testing and then motoring back over to the slip we are in. During that time we ran at different rpm's doing testing and it sure seemed we had the exact same issues just at a higher engine rpm.

Below the exhaust elbow is a section of 4" exhaust hose that is only 3-4" long before a large 90 degree fiberglass elbow. I have no issues drilling a hole in this for a fitting to test back pressure in the exhaust and then just replace the small section of hose. I am hoping to find someone who can help me with this on Monday. Where we are has no auto supply shops or marine stores close and we have no car.

I do now have the name of a guy who can test the compression and I hope to discuss monday morning having them come out and properly test the engine, both compression and exhaust back pressure.



Terry

[Laidback]

Terry,
That was a good test - here is a place that you can buy a Compression tester for a Yanmar - has gauge, hose and dummy injector, at a good price:-
Yanmar Tractor Parts: COMPRESSION TESTER KIT
Remember when removing the real injector to wrap it up so that you don't spray fuel all over the engine compartment.

[Tspringer]

Now that the engine has fully cooled off again, I checked the oil again. It does appear that I am still making oil..... fuel continues to dilute the oil.

So either there is something internally wrong with the injection pump, or one or more cylinders is dead under load and lots of the unburned fuel is pouring past the rings into the oil.

I was considering heading south early tomorrow morning but may wait and try to get a compression and leakdown test plus a back pressure test done on Monday. I don't want to run the engine with it diluting the oil so bad as that could ruin the bearings.... though that may not matter if the entire engine is toast anyhow.

She fires right up and idles smooth plus seems to run smooth and well. What on EARTH is the problem ?!?!?!?!??!?!?!?!


Terry

[never monday]

Terry,
Low on the IP should be a 14mm headed banjo bolt. This should be the oil return line from the IP.
Open it up and see if fuel is mixing with the oil here.

[Chief Engineer]

I think we are getting close.

Terry......with the engine running.....take your 17mm wrench and just crack each fuel line at the injector.....you should notice a drop in rpm if that cylinder was firing.

I apoligize if this was suggested before, but sometimes we need to backtrack a little.

[never monday]

Originally Posted by Chief Engineer

I think we are getting close.

Terry......with the engine running.....take your 17mm wrench and just crack each fuel line at the injector.....you should notice a drop in rpm if that cylinder was firing.

I apoligize if this was suggested before, but sometimes we need to backtrack a little.

that's a quick and easy test. I'm doubtful it will show anything. I have a feeling this engine is down on all 4 equally.

[Tspringer]

NM and Chief.... I can do the test cracking each injector line again tomorrow. Should this be done with the engine at idle out of gear or under load?

When we did this before, the engine rpm clearly dropped when each line was cracked though on 2 cylinders the drop was more pronounced. This was out of gear at idle and it was before the injectors were replaced. Remember, the engine also did not run as smooth at idle before the injectors were replaced but after the new injectors it started better and the idle is now smooth with no engine vibration on its mounts noted.

I will also crack the 14mm line on the bottom of the IP tomorrow and see if I can tell if the fuel is getting into the oil inside the IP.


Terry

[Laidback]

I believe each cylinder should read 470 lb PSI (when the cylinder, piston and rings - valves, seats and guides are within specification limits)

[shakey doug]

Have not read all past posts so this may have already been suggested ,have had same symptoms and found blocked or restricted injector fuel return plumbing;suggest check system for correct operation of any gate v/vs ete. Undo fitting at injector rail and test run UNDER LOAD.

Good luck, Shakey.

[hpeer]

Boy, do I feel your pain. I think I would be reduced to tears, or terror.

My guess, based upon far too much embarrassing experience, is that it is probably something pretty simple. For example I have had improper washers cause me fits more than once. Once a copper compression washer was replaced with felt.

Another time the guy used silicone (vs compression washer) in a water line which caused an intermittent overheat condition. I never did find this one. Some old shade tree expert came to it in about 3 minutes.

Perhaps in taking the bits off and putting them back something went awry. A missing or crinkled washer/gasket that is leaking. A cross threaded bolt that feels tight but that leaves a fitting leaking. A loose bolt? Who knows.

I find it sometimes pays to take a couple of days off. Forgetaboutit. The mind will work on it anyway. Then, perhaps, the dime will drop.

I wish you the very best of luck, for I see myself in your shoes someday.

By the way, we are just now buying a boat with the same engine. So I have been following this with more than passing interest.

[sandspur]

If still in Jax & need inj pump or inj work done check with Roys Diesel on Highway Ave. They do good work & are very helpful

[farmerboy]

I just came back to see what the solution was and I am amazed to find that this damn engine appears to have beaten a gaggle of Yanmar specialists and the combined intellect of the worlds yachting fraternity! (including some VERY knowledgeable engineers). I cant wait to get up each morning and read the next episode of Yanmar v the rest of the world!

I can't imagine how fed up you must feel by now - just thought I would let you know that I am wishing you luck and keeping my fingers crossed. I think we should all have a party when this is over!

Best wishes,

John

[Tspringer]

Fed up doesnt even come close... despair is more like it. AT this point, everything is in question including whether this cruise will even happen. I am going to do the testing cracking the injectors later this morning and we are looking at motoring back up river toward Ortega and getting back into a long term slip as its clear whatever the engine issue is its not something that will be fixed in a matter of days. We have to slow back down and try to get a handle on what we really need to do. I will need to fly to Atlanta and drive our car back down so we have some transportation and we will have to start re-evaluating our entire plan.


Terry

[Tspringer]

Originally Posted by shakey doug

Have not read all past posts so this may have already been suggested ,have had same symptoms and found blocked or restricted injector fuel return plumbing;suggest check system for correct operation of any gate v/vs ete. Undo fitting at injector rail and test run UNDER LOAD.

Good luck, Shakey.

The fuel return lines are all brand new, there is a "T" hard line at each injector where fuel not pushed through and used by the injector bypasses and circulates back to the tank. They are in parallel so if one was somehow blocked then no fuel would be returned for any of them.

I did replace all of these return lines and all of the rubber fuel lines are also new. I installed a Filter Boss Commander dual filter system and replaced all of the fuel related lines at that time (during all the big refit work). I will review all of the fuel lines and return lines today and look for any issues and check for any blockages. Its easy enough to remove the return line to the tank and have it routed to a bucket while running and see if any fuel is getting returned to the tank.



Terry