yammar diesels turbos

[rdemay]

hey all..back with another question..i capt a small fishing boat that has twin yammar diesels 315 hp. they are turbo charged. when we get going they seem to smoke quite a bit. i mean Quite a bit. thick black that last abot 15 -20 min befor it calms down.. all the injectors were changed this past spring.. i took off the air cleaners and can spin the turbos but they don't spin as freely as i think they should. how should they spin is my question??

 

[rodbolt]

Re: yammar diesels turbos

I doubt you have a turbo issue. they spin rather freely but I am thinking you have an injector issue. usually turbo problems such as leaks or bad bearings show up as catastrphic failures.<br /> by the time you get a sympyom of a turbo failure its toast. occasionally an oil seal will fail and allow crankcase oil into the airstream but that causes blue smoke. does your system use a waste gate ?<br />that thick black smoke indicates to much fuel for the availible air.

 

[searay3]

Re: yammar diesels turbos

A failed turbo would cause a huge loss of power and continueous thick black smoke. Are both engines showing the same symptoms? Were the injectors changed to try and remedy the smoking issue? I would be looking at fuel pump and air intake issues. Extended idling can cause smoking while getting underway, but not as much as your describing.

 

[QC]

Re: yammar diesels turbos

Originally posted by rdemay:<br /> thick black that last abot 15 -20 min befor it calms down..

I agree with both rodbolt and searay on the turbos, but I can imagine a scenario where they spin slightly faster when they get good and hot. I also agree that black smoke is too much fuel for the available air.<br /><br />What I don't understand is why it goes on for such a long time and gets better. I would think that they would be fully warmed up surely by ten minutes, probably less than five. If it was 15 - 20 seconds I would say that it might be nothing or the fuel air ratio control which may have a diaphragm that is bad, but I don't know Yanmars. After it clears up what happens if you back out of the throttles all of the way to idle speed and then get back into the throttles and back to cruise? Does it take another 15 - 20 minutes?<br /><br />I am also confused about it happening with both engines . . . Which gets back to the injectors question that searay asked. Did they do this before they were changed? Need more history. Have they ever been right? Also, does the boat pick up any speed when the smoke starts to clear?<br /><br />If your engine room is clean I would try running them without the aircleaners for a short period, just to get some info to work from . . . I don't worry about contaminted air on the water, but if there is something loose they can suck in, they will <br /><br />Oh and I just thought of something else. Maybe air leaking between the turbos and the intake? I could imagine some sealing rings tightening up too. Do they sound any different when it clears? i.e. maybe the turbo whine changing. You're not running these 100% I bet, so I don't understand why they would overfuel, that's why I am thinking air.

 

[rdemay]

Re: yammar diesels turbos

thanks for all the input..this is a boat that i capt on. so i don't know to much history but it started this spring. the owner had all injectors replaced and it still is there. ithere is only a foam air cleaner and i have removed and cleaned these so they are not the problem. now the injector pumr fires the fuel to the injectors and does it also measure the amount? it does seem like it is getting to much fuel. also once you are up to 2000 rpm and then try to go up to 2400 they seem to take there time getting there.plenty of power but just sluggish.. i am going to take off the air cleaners and eyeball the turbos to see if they ar running ok. rodbolt--what is a waste gate?? thanks again....

 

[rodbolt]

Re: yammar diesels turbos

depending on the set up and I have only a pasinig familiarty with the turboed yanmars, there has to be a method of controling boost. the common method is a wastegate, can be actuated in many ways. it just dumps excess pressure and controls boost. not all applications have it. my uncles 6cyl turboed Izuzu did not it just used a low pressure turbine.its possible that the exhaust stream side of the turbine is carboned up or defective. but its odd both engines do it. did they both start showing the symptoms at the same time ?

 

[QC]

Re: yammar diesels turbos

My guess is that there are no waste gates. Waste gates are for apllications that need a lot of air at low revs for DEEP torque rise AND low emissions. Marine engines don't need either. The waste gate woul dthen blow off the excess bosst at higher revs and power settings. we have lived without them in almost all applications except recently with automotive. Much more common on turbo gasoline engines.<br /><br />My air cleaner comment was only to see if a slight increase in air solves the issue, removal of clean and new aircleaners would still increase flow . . .<br /><br />I still have a problem about them smoking steady at less than full load. With both of them smoking could there be an air restriction to the engine room itself? Some piece of trash in the vents or similar would explain the same lack of air to both engines.

 

[steamboatwilly]

Re: yammar diesels turbos

Many years ago,I was around a lot of old International diesels.The manuel said:Raise the time until it stopped smoking:I dougbt if this is your problem,but something to think about.

 

[searay3]

Re: yammar diesels turbos

I believe fuel pump calibration would be the next step. The shop that did the injector replacement should have done a compression check and probably discussed fuel pump calibration with the owner. It is expensive. About $600 bones around here if you take it off the motor and bring it in. Age of the engine also plays a role as compression is extremely important for efficient operation.

 

[QC]

Re: yammar diesels turbos

Originally posted by searay3:<br /> I believe fuel pump calibration would be the next step.

I don't agree. If this started on BOTH engines at the same time, I don't think it's timing, fuel injection pump, or anything independently mechanical. Now if they started acting up at different times, maybe, but if it is both of them I still think it is air . . .<br /><br />I also think it is important to know if this is happening at full load or at some other place in the op range. Diesels rarely smoke black at part load settings, it is most typical under acceleration or full load.<br /><br />Oh, and despite my earlier comments, the Yanmar may in fact have a wastegate, but again, I can't think of why they would both fail simultaneously. All of my comments assume that nobody was monkeyin' around with them before this all started.

 

[rodbolt]

Re: yammar diesels turbos

I tend to agree with quietcat. seems we may need more information on how and when both engines started showing problems. I think its time for a competent yanmar tech to inspect the engines. a quick way to isolate if its engine box air is to open the engine box hatch and attempt to recreate the problem.