Possible Turbo Problem

[egaito]

With insurance finally in place, we went out yesterday and after about an hour of running around at 9kts, tried to run her up and clean out the engines. The Starboard engine wouldn't go past 1500 RPM, and was blowing black smoke.

Last time she was out, both engines ran well, and we ran her on plane for a good while. Other than sitting, nothing has changed mechanically.

The bottom was just scrubbed, so I don't think it's buildup, the other engine reaches 2000, but it takes both of them running to push us over the hump.

The first idea that came to me was that perhaps a turbo is "stuck" from sitting, which I'll be checking shortly.

Any other ideas, things to check?

Thanks,

 

[krush]

make sure there is no growth on the props.

 

[egaito]

make sure there is no growth on the props.

Done last week, with the bottom, and checked last night while the line was being cut off...but that's another thread ;-)


I just pulled the filters off, and spun them from the front, by hand. The blades were clean, and they spun effortlessly.

Are the turbines on the exhaust side on the same shaft, or do they spin independently? The back end is of course not trivial to get to.....

 

[Brian Degulis]

Same shaft Check the air shutdown housings (emergency stops) If it was pulled acidentally when you where laid it might have closed. If it's working right the engine shouldn't run at all but if it's binding or stuck it will close partialy. So it runs fine at low RPM but can't get air for full load. If that's not it and props are clean and straight check the boost pressure to see if it's a turbo problem

Brian

 

[egaito]

Update:

Spoke to our mechanic, who had us check a couple of things, one being to look for the presense of bubbles in the Racor. Ang cranked them up last night, and reports some bubbles, about the size of soda carbonation bubbles, coming from the bottom of the glass bowl. Not a lot in the slip, but under load, this could be causing us some issues.

Did I squeeze an o-ring too tight on the last filter change, or are there other common causes for air entry into the system?

Thanks,

 

[MikeP]

I would expect air in the fuel to cause a fuel starvation problem; black smoke indicates overfueling. The previous suggestions - turbo problem or air door (or other air restriction - clogged air filter, etc) seem more likely.

Will the engine reach no load WOT RPM specs or is that also restricted to 1500 RPM? That would be a good check of governor/rack settings since it takes very little power (air/fuel) to achieve no load WOT. Any black smoke under those conditions? If no, it pretty much has to be an air restriction of some sort under load which could be a turbo.

 

[surfdancer45]

Sounds like a fuel/air problem especially if you are getting air in one Racor. Check the O-rings (small orange one around handle and large one around filter canister. If you still get air bubbles you may have small hair line crack in body of Racor. This is a fairly common problem. I guess you already checked the filter as a dirty filter would cause same symptoms of fuel starvation. Let's us know how you make out. Bob

 

[MikeP]

Good points and certainly the fuel system needs to be corrected if there are air bubbles in the racors but the symptoms (black smoke) are not fuel starvation; the symptoms indicate "air starvation."

So we need to determine why the engine is not getting sufficient air to properly burn the fuel (or - less likely - why the injectors are over-fueling).

 

[thoward]

Same shaft Check the air shutdown housings (emergency stops) If it was pulled acidentally when you where laid it might have closed. If it's working right the engine shouldn't run at all but if it's binding or stuck it will close partialy. So it runs fine at low RPM but can't get air for full load. If that's not it and props are clean and straight check the boost pressure to see if it's a turbo problem

Brian

That happened to us. It only closed 1/2 way so the enging would idle fine but would pour black smoke over 1200 rpm.

 

[Angela]

Update, sort of:

The fuel filters, despite them having been changed recently, were filthy. Not quite the "tar baby" that we sometimes find on the genny filter, but black nonetheless. I changed those and the O ring on the T-handle and the rubber lid gasket. Because I'm working in there tonight cleaning my bilges and don't want to heat it up any more than it already is here in Miami, I'll fire up the engines tomorrow and see if I see bubbles.

Note that the filters on BOTH of the engines were the same degree of dirty. The starboard engine runs fine, and the port doesn't. So, I don't think it is really a dirty fuel filter issue, but they were dirty so I replaced both of them...'cuz I'm supposed to!

That's all I can add to this thread since some of this is still over my head. I don't mind taking orders and doing stuff, checking stuff, etc. but sometimes I just don't know what I'm doing - I just do what I'm told and then report what I see.

Hey, diesel fuel makes a nice cuticle moisturizer...and I don't really mind the smell; uh..I kinda like it.

 

[Passages]

Hey, diesel fuel makes a nice cuticle moisturizer...and I don't really mind the smell; uh..I kinda like it.

Are you saying you would prefer a load of diesel to some fancy French perfume?

 

[Angela]

Are you saying you would prefer a load of diesel to some fancy French perfume?

Most definitely! I can take 775 gallons. LOL I know where my priorities are.

 

[egaito]

Most definitely! I can take 775 gallons. LOL I know where my priorities are.

Now THAT's a boat girl.....

 

[SeaEric]

Update, sort of:

The fuel filters, despite them having been changed recently, were filthy. Not quite the "tar baby" that we sometimes find on the genny filter, but black nonetheless. I changed those and the O ring on the T-handle and the rubber lid gasket. Because I'm working in there tonight cleaning my bilges and don't want to heat it up any more than it already is here in Miami, I'll fire up the engines tomorrow and see if I see bubbles.

Note that the filters on BOTH of the engines were the same degree of dirty. The starboard engine runs fine, and the port doesn't. So, I don't think it is really a dirty fuel filter issue, but they were dirty so I replaced both of them...'cuz I'm supposed to!

Hey, diesel fuel makes a nice cuticle moisturizer...and I don't really mind the smell; uh..I kinda like it.

Angela is my hero! You go girl!

 

[Angela]

I changed the fuel filters, filled the cannister up with diesel (priming pump sucks at that - I ended up unhooking the hose and getting myself a couple of cupfuls of diesel and pouring it into the filter cannister), put the back lid on, removed the turbo filters so I could see the blades, and fired up the engine. Man, I love the sound of those DDs! Turbo blades spun nicely.

When I shut down the engine I heard a very loud hissing noise which was coming from a fitting on the air compressor tank - it's a big leak with a strong flow of air coming out - it wasn't hard to find at all - took about a half a second. It was quite obvious.

What does that air compressor tank do for the engines? If it has anything to do with the operation of the turbos, then it wouldn't make sense that it the turbos work on one engine and not the other, would it? We always knew the tank would not hold pressure after shutting off the engines, but this leak is rather large now. I do not recall ever being able to hear such a large hiss; in fact, I have never been able to hear it off-gas before, and we've never known the precise fitting that was going bad; granted we hadn't started looking real hard for it either - we sort of assumed it was the fitting at the end of the air hose that's attached to the tank for air tools - it's got a fitting on it like you'd put air in your tires. We don't have any air tools, yet.

So what's next????? Other than fix the compressor tank.

 

[Pascal]

air tank is only for accessories, on our boats horns and windshield wipers.

unrelated to engines, turbos, etc...

 

[Nonchalant1]

Ang,

There are two fuel filters. You said you "put the lid back on" so that means you changed the primaries (RACORs). Now you also have to change the secondary filters. They're like a little oil filter cannister that hangs off the sb side of the engine usually. It needs to be filled with very clean diesel too before you screw the new filter can on.

Also, I didn't hear if you checked your emergency air damper on the bad enginne. It site on top of the blower housing and a spring loaded hasp holds the damper door open. If yo pull the emergency shutdown, the door inside the housing closes and stops the engine. It can be checked by tracing the red actuator cable to the top of the engine and pulling the cable or the little actuator arm while the engine is off and you'll hear the door close inside and see the arm move. Then move the arm back to where the door is fully open and the spring hasp holds it open until the next cable pull. Check one engine damper door operation against the one on the good engine. Make sure you note exactly how it's set up before you touch the good side, so you can match that on the other engine.

Those two are what's next. If you've done those, it may be in the fuel controller (the "rack") or the injectors.

Doug

 

[egaito]

The air doors have been checked, thrice by now I think, and as best we can tell are open. The trigger, and reset seems to work fine.

We have not however changed the engine fuel filters....it's worth a try.

 

[Maynard Rupp]

Ed and Ang..I know I am supposed to be a gas engine man, but I have just gone through a stint on our yacht clubs volvo diesel in a workboat. Ours was "overfueling", and I can tell you that makes a stinky white smoke. It turns out to be a bad injector. The experts told me that black smoke is always a lack of air, not fuel. Too much fuel is white. Stuck turbos limit rpm to a certain value depending on the engine and make black smoke. That's Maynard's .02.

 

[Angela]

FIXED!!!! A change of ALL filters, some diesel kleen directly into the secondaries and the girl rides on plane again!

Mario and I are on our way to CDR. We're closing in on Pascal ahead. He's on one engine. I wonder how he'll handle two Hatt wakes, one on each side. LOL