Smoke ref fuel filters

I have Cummins 330B's. Just out of the blue, the left engine started smoking pretty badly on start up. It would clear to some degree after a few minutes but still I wasn't happy with it since it was a sudden new development. Of course my immediate thought was a fouled injector since it was white/grey smoke with a pretty good sheen of unburned fuel on the water. I called my local diesel guy and his first suggestion was to change the fuel filters. Now I don't know everything about diesels, but I didn't see how semi-dirty filters(60 hours since last change) could cause this smoking issue. So I humored him(and myself) and changed the primary and secondary filters on both engines since it was cheap and easy(my wife always said I like cheap and easy). I started it right after and the smoke was still there but it did seem to clear up quicker and cleared up better....back to the way it was before. Still not convinced, I let it sit overnight to let it get cold and went to start it this morning. It smoked just a teenie bit(a diesel mechanic would likely not even have batted an eye) and cleared up quite quickly...basically back to normal...although I am still not convinced. I am going out of town for 4 days so I will start it dead cold in 4 days.

Anyway, I am still having a hard time figuring how 60 hour filters could cause a smoking issue(poor fuel atomization). To me, the fuel either gets there, or it doesn't. And if it gets there it should be clean? I will admit, the 10 micron primary was pretty damn dirty. And the spin-on factory spec Fleetguard was not observable. Maybe I should have cut it open? The right Racor was significantly cleaner....most likely because I have been fighting an issue on that side and have been changing that side more often.

Anyway, talkst amonst yoselfs!!!...Discuss!!!

Polish your fuel.

Thanks for your reply. But you missed the point. Can dirty fuel filters cause a smoking issue?

I have had the fuel polished twice in the past few months for different reasons. I use my boat a lot and these engines can guzzle the fuel. IOW, the fuel does not hang around in the tanks for very long. In top of that, the fuel system delivers approx 3-4 times more fuel than the engines actually use and the rest is returned. So the fuel is being polished whenever I run the boat.

Dirty filters don't change the fuel specs directly but the stuff that makes them dirty can. If you have enough buildup of crud that it passes through and reaches the injector pump it might cause cavitation or gassing issues (sort of like vapor lock) or the crud may change the spray pattern temporarily or impact proper injector operation.

What you are saying is not consistent with what you're doing - you should only have to polish your fuel in time measured in years, not months. You can't do any diagnostics with dirty fuel and yes, dirty filters will definitely affect the way the engine runs. The pumps produce too much fuel so there is never any chance of starvation, plus the excess fuel is necessary for cooling, so a diminished flow because of dirty filters is an issue. You need pressure and volume and you need a nice clean clear stream of air, that's pretty much it... Do your engines use glow plugs? Maybe you've got a dud on one cylinder, or perhaps intermittent?

You shouldn't have so much crud in your fuel, unless you're buying it at a crappy dealer, the stuff in your tanks should be clean. It comes from the refinery with some water in it, in suspension, but it's only when you let the water get out of hand that you get biological growth. I doubt if the fuel you return to your tanks has enough volume and swirl effect to pick up the crud that lies on the bottom of your tanks and wash it through your filters. It sounds to me like you need to get someone in to clean it and solve the first problem.

Rick, if you are getting contaminants past your fuel filters, you are in big trouble. The injector pump (older engines, new ones have fuel pumps) will die an awful death if you let any crap get in it. Last I saw, the fuel pump for a Cummins late model diesel is around $5000, made in China (thank you Cummins).

Baker said:

Anyway, I am still having a hard time figuring how 60 hour filters could cause a smoking issue
!!!

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Me too

Xsbank said:

Rick, if you are getting contaminants past your fuel filters, you are in big trouble.

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Yep, that's a good reason to change the filters.

Xs, the boat had sat awhile before I bought it. The fuel was polished shortly after I bought it. I then had a fuel cooler issue that was returning water to the tanks. Polished again. That is why I said I had it polished twice for unrelated reasons. The filter that was replaced on that side was by no means hideous. Just dirtier than a clean one

Rick, I was thinking the same thing that maybe an injector was temporarily fouled. Anyway, I am still not totally convinced all is well. I will be if I start it this weekend and there is no smoke.

Baker said:

I then had a fuel cooler issue that was returning water to the tanks.

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Could be related. Deposits on some part or parts that created timing or delivery issues then went away with the water wetted filter elements. Kind of difficult to diagnose after the fact and from a distance.

Have you fueled since or before the problem seemed to have diminished?

I know this is an add, but the smoke answer might be found in this article:
Colour of engine smoke and when it occurs tells about internal condition

A shot of Stanadine will be a help if the injectors got some crud.

The filter might not be passing enough fuel for the engine to operate properly .

On SOME engines the fuel system passes 5X -10X as much fuel as the engine can burn ,
on others (some Bosch style) the only excess fuel is what leaks out of the injection pump.

Many large trucks use a special system to remove air from the engine supply lines, which they claim gives more power and stops some smoke.

RickB said:

Could be related. Deposits on some part or parts that created timing or delivery issues then went away with the water wetted filter elements. Kind of difficult to diagnose after the fact and from a distance. Have you fueled since or before the problem seemed to have diminished?

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Nope. Not since the smoke issue. But I have many times since the water issue. I will likely add fuel this weekend.

Am thinking more and more that it is (was) a case of fuel contamination possibly related to the water event and tank cleaning that lead to light corrosion on some fuel injection components that useage has removed.

Keep in mind that all diesel contains a bit of air, if you lower the pressure on the fuel by clogged filters, some of that air will come out of solution and if it makes it to the injector pump it will create metering issues. Those issues are not equal among plungers so one cylinder might get more or less fuel than another. The governor doesn't know that a single cylinder has problems, it just tells all of them to deliver more fuel to maintain setpoint speed. This overloads some cylinders and can create smoke.

The same thing can happen if a plunger or injector is "sticky" because of contamination or corrosion. Useage creates wear and polishes the rough spots created by minor corrosion ... self healing if you like and the symptoms go away... though the damage might be so slight that it will never create a problem in normal operation, just shorten the service life but in your application you'll probably never know.

I will let you know for sure Sunday morning if it is "self healed". I wasn't fully convinced the other day when I observed it.

Thanks for the explanation, Rick. I am not sure I will ever fully understand how a governor works on a Diesel engine. But I keep trying every time you explain it. One day the light may go on.

Baker said:

I am not sure I will ever fully understand how a governor works on a Diesel engine. .

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You tell the governor how fast you want the engine to run. There is a little man in the governor who opens the fuel faucet until the engine speeds up. If it slows down the little man opens it a bit further. If it tries to run away the little man closes the faucet until it does what it has been told.

Rick that explanation was so clear even a moron like me could grasp it. Thank you

Kinda like a governor on a Garrett turbine!!!

Baker said:

Kinda like a governor on a Garrett turbine!!!

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That's it! But instead of sending oil to the prop it moves the handle on the faucet.

Until you get to electronic engines, there is a flyball and speeder spring that does the heavy lifting.

I was actually talking about the engine. Garrett's were initially designed for work as oil field pumps and generators. They worked at only one speed...100%. If they slow down...the underspend governor dumps fuel in. Same thing if they get too fast. When they started hanging them on airplanes as turboprops, they made them two speeds....high and low. Low I think was 97% if I remember correctly.

To give you an idea....we operated Metroliners in the upper Midwest. The upper Midwest is known for quite a bit of snow in the winter. If you dragged you propellor disk thru a snow drift, guess what happened??? The propellor would slow down...underspeed governor would dump fuel in and if the load on the prop was still there, pieces of the engine would come out of the exhaust in molten form. Other than that, they are fine engines....obviously not their fault in this case. Our company would trash a couple of engines a season. We lived in fear of small snow drifts barely detectable at night.

Baker

Assuming you have Racors, it sounds like a normal pass through of water that the filters could not catch once they became saturated with too much water. Water then burned poorly and or damaged an injector.

In any event, change your filters at say 50 hours until problem gone. Remember the good old days of Mercedes diesels having a water drain, if you let it get too full, yup smoke appeared.

sunchaser said:

Baker Assuming you have Racors, it sounds like a normal pass through of water that the filters could not catch once they became saturated with too much water. Water then burned poorly and or damaged an injector. In any event, change your filters at say 50 hours until problem gone. Remember the good old days of Mercedes diesels having a water drain, if you let it get too full, yup smoke appeared.

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I keep a very close eye on the Racors. Most of the issue was on the right engine and all injectors on that engine were replaced. The bowl on the left engine has been crystal clear(red) with no water. Now if you're saying that the water somehow made it past the Racor without showing in the bowl...then you got me there!

Forkliftt use govenors to limit max RPM (seems some operators don't respect what max RPM should be). Old school diesel injector pumps operate the same. Today's LP engines RPM are controlled by an ECM, but prior to that most used a velocity (pancake) govenor bolted beneath the carburetor. As the engine RPM increased to max (usually 2200-2700) the flow of air of course increases. The govenor has a throttle plate of sorts in the airstream attached to an adjustable spring. The spring tries to close the plate, the movement of air tries to open the plate. Set point is achieved by adjusting spring pressure to overcome the air movement at the right speed.

Baker said:

If you dragged you propellor disk thru a snow drift, guess what happened??? The propellor would slow down...underspeed governor would dump fuel in and if the load on the prop was still there, pieces of the engine would come out of the exhaust in molten form.

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Seems odd, we flew the -11 and -12 versions in the snowy parts of Idaho, Montana and Utah but never had that problem.

The only issues I recall with overtemps were the rare hung start or what some called "super cruise" that fooled the SRL computer into thinking it was operating in a different regime than it really was.

Flying the tube was really paying dues wasn't it? Wouldn't trade the experience for anything but have no desire to repeat it. My first was a 226AT freighter with little 840HP -3s on a run from SEA-MSO-HLN-BIL. It sure beat the C-45 though.

RickB said:

Flying the tube was really paying dues wasn't it? Wouldn't trade the experience for anything but have no desire to repeat it. My first was a 226AT freighter with little 840HP -3s on a run from SEA-MSO-HLN-BIL. It sure beat the C-45 though.

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SRL Computer???!!!!...I never would have remembered that if you would not have said it!!

The vast majority of my commuter experience was in a Fokker F27 and the SA227....no autopilot or flight director. When I went in for my Continental interview, they had us fly the DC9 simulator. A very basic profile that took about 20 mins. When we were done the "administrator" asked what kind of experience I come from...and I told him...and he said, "It shows!"..and then he went on to grumble about all the "kids" that come from Glass only airplanes and how they can't fly any more...hahahaha. They aren't supposed to say a word after those deals. I don't think I was more than 10ft or 1 degree off during that deal...those instruments were frozen. I had never flown a jet and will have to credit the DC9 for being a very fine flying aircraft!!! And I will say that I am nowhere near the pilot(stick and rudder) I used to be. We used to fly those bitches....and into god awful places where it was always a crosswind with braking action poor and 1/2 mile vis. Marquette Michigan is a perfect example of what I am talking about. 250+ inches of snow a year!!! By the end of the winter, we were landing in "canyons" with the plowed snow pushed up on each side of the runway and taxiways...it became surreal.

Anyway, back on topic and no more bragging...hahaha..... I am headed down to the boat to give it a start and see what kind of smoke comes out of that left engine.

It is funny...the wife and I are separated and she asks..."How's my half of the boat doing?". And I replied, "Your engine is ****ing up!!!":lol::lol::lol::lol: