Our Cummins is sick.......

Hi all. Yesterday*the 330hp 6BTA Cummins in our 2003 Mainship 390 started blowing black smoke and losing power. First time it's ever smoked at all. The engine has 790hrs on it, almost all of it in fresh water.*We were 2hrs out so limped back to the marina, with the engine feeling like it was running on 5cyl. No abnormal temp. or oil pressure readings, or unusual noises.*The oil level, however, is now way up. I think it's likely*fuel contaminated since there's no evidence of water on the dipstick, and coolant level is normal. I have no diesel engine expertise (but lots of hands-on gas engine experience)*and*would like*to establish what has failed before I call in the specialists. I'm hoping someone in the group can comment on my approach to this issue, which I'm hoping is a failed/stuck injector: 1/ Drain oil and check for contaminants, both visually and by smell(presence of fuel).* 2/ change filter and refill with fresh oil. 3/ Restart and "crack" injector supply lines to try and identify bad cyl.(read about that technique on Boatdiesel forum)*4/ Remove injector and inspect/clean/get pressure tested (I believe any diesel shop can do this?) 5/ Inspect the suspect cyl. with a borescope. 6/ Pray!

There was no evidence of unusual blowby, I'll check into that more when I go back to the boat. I added a "puke bottle" to the crankcase vent in the spring so the evidence should be in there.

Needless to say this is a very troubling development and totally unexpected......the engine has been maintained to Cummins standards, the boat is propped correctly and fuel properly filtered (Racor 2micron), and stabilised during off-season. It always starts instantly and has run flawlessly up to now.

As I stated before I have no hands-on diesel experience, but I am hoping to learn real fast! Any tips/guidance from those with more experience in "the holy place" on their boats would be greatly appreciated.

Thanks',

Nick

*

If you recently added a "puke Bottle" have you run much since doing that? Maybe that installation has something to do with the problem?
How about the air intake or filter, I have never seen it on a boat but tractor diesels will send out black smoke when the air filter is plugged up.
Steve W.

I've probably put about 10hrs on since adding the catch bottle to the crankcase vent. It is still vented with the same diameter hose, which now goes in/out of a small plastic gas can to eliminate the drips. This shouldn't cause any backpressure, but I'll double-check the installation, just to be sure. Thx.

Post your problems with the Cummins experts on boatdiesel. It could be several things, starting with over prop*----- etc. Any chance of seawater getting into engine via exhaust elbow? This has been a weak point on some Mainships.

Hi Nick,

The puke bottle should be irrelevant. On my 5.9 I just added a tee in the crankcase vent line and put a bottle at the low point, been like that for years.

Agree it is a fuel issue, whether it is bad fuel or an injection issue, could be the high pressure pump too, hard to say at this point, but you should call a qualified mechanic over for a look see.

good luck

Zero chance of water backtracking up the exhaust.....we're on a very placid river here (Rideau) and the boat never gets exposed to waves/wakes whist anchored. But also, the no wake rules*limit the opportunities to "throttle up"*and work the engine harder........I do it when I can, and the stretch in front of our marina is quite wide so I can usually finish a cruise that way, which I understand is a good idea.

Can anyone tell me if special tools are required to remove an injector on a 6BTA?

Injectors are not the issue, unless you pumped a bunch of water through due to very bad fuel. They should be good for 6000 + hours.

If your exhaust elbow went bad, it is not difficult to get a back flow of seawater. Expect 5 to 8 years out of an elbow before you give it a good check.

Again, best you repost on boat diesel.

*

"Remove injector and inspect/clean/get pressure tested (I believe any diesel shop can do this?)"

Most any diesel INJECTOR shop, not just a general repair place with a toolbox and a set of hammers..

Black exhaust is too much unburned fuel or too little air.

Is the engine turboed? If so I would start there.

FF wrote:
Is the engine turboed? If so I would start there.

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*Yes, it's turboed. Other than a mechanical failure of the turbo what would I look for? If it's dirty in there, how do*I clean it?

The very FIRST thing I would look for based on your description is a blown compressed air hose or connection. Follow the air plumbing from the turbocharger output to the intake manifold. Look for a broken hose or more likely a connection where the hose slipped off.

You can clean the compressor side of the turbo easily using brake clean, etc. Put a paper towel or oil diaper under the opening and spray and let the yuck collect in the towel. But if it spins freely and is not hitting the housing you likely don't have a turbo problem.

Injectors are easy to pull on a Cummins 6B if you get to that point. I have done many on trucks. You can do it with a prybar once the fuel lines are out of the way and the retaining nuts are removed. I forget the size of the retaining nut (maybe 24mm). However, as stated with only 800 hours on the engine injectors are not likely the problem unless you have had water in your fuel.

*

OK, thank you for the tips, I'll certainly be looking at those areas when I go back to the boat, instead of focussing solely on injector issues. Maybe, as a neophyte diesel owner, I've been swayed by all the hype about fuel additives, injector cleaners etc., assumed the problem was with the injectors,*and have overlooked the possibility that the problem is elsewhere. Kind of like losing one's "situational awareness" during troubleshooting. I'll try and keep a logical, open mind when I go back, except when I'm praying, of course............

*

Nick

tachyon wrote:
* The oil level, however, is now way up. I think it's likely*fuel contaminated since there's no evidence of water on the dipstick, and coolant level is normal. *
--------------------------------------------------------
I'm not a 6BT mechanic but a*couple of other things to check:

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(Also does your engine have electronically fired injectors.* If so, a broken wire will cause the engine to misfire on one cylinder.* Volvo is currently going through a recall on bad engine injector wiring harness on several of their engines. *Running them in this manner has caused some severe damage to the pistons.)

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From the symptoms you are describing I would also check:
** The engine fuel supply pump for a broken diaphragm.* This will leak fuel oil directly into the crank case. *An overfilled crankcase, specially with diesel oil, will suck oil up into the cylinders and put out a heck of a lot of smoke and will stink to the high heavens.
*** A stuck valve or broken exhaust valve spring will also cause loss of compression and the cylinder not to fire.* Guess where the fuel oil goes that the injector is faithfully pumping into the cylinder?* Right into the crankcase.
***Have you had your valves adjusted lately?* If a pushrod gets bent or too loose and jumps off the rocker, you have the same issue as above, with fuel oil accumulation in the sump and a misfire on that cylinder.
Taking the valve cover off and a visual inspection while rolling the engine over slowly will reveal any issues with the valve train. Look for a loose push rod and rocker not moving.
If you can't find it, don't run the engine under load until it's repaired.
Larry B


-- Edited by Edelweiss on Monday 25th of July 2011 07:31:45 PM

Take out the turbo and see if it still spins freely.

I would also look for a leak in the intercooler for a major air leak..

"Maybe, as a neophyte diesel owner, I've been swayed by all the hype about fuel additives, injector cleaners etc., assumed the problem was with the injectors,"

This is because folks are always looking for a quickie solution , and most of these "cures" have an immense markup, needed to pay for the advertising.

Take out the turbo and see if it still spins freely.

*

No need to remove the turbo to check for that on this engine.


*

I think before yanking injectors, valve covers, and turbos you had should hire a good mechanic, as the owner of a 6BT I'd like to hear what the problem is, please let us know.
Thanks,
Steve W.

Steve wrote:
I think before yanking injectors, valve covers, and turbos you had should hire a good mechanic, as the owner of a 6BT I'd like to hear what the problem is, please let us know.
Thanks,
Steve W.

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*I agree.* Don't jump to conclusions.* A perfectly good running engine for the most part doesn't just blow up.* Stick to the simple stuff first and go from there.* A good technician is in order.* Circuit boards and electronics can reek havoc and without the proper test equipment you are shooting in the dark.


-- Edited by JD on Tuesday 26th of July 2011 06:27:40 AM

Thank you all for your responses and words of wisdom. I really appreciate it. There aren't a lot of diesel boats in our area, hence a shortage of local technical help. Our marina does have a diesel specialist it can call in from another town, if required. I intend to look at the basics as you've suggested and just go from there.

This engine issue comes along just after reading an article in the latest Passagemaker about a Cat diesel owners' experience in using*regular oil*analysis to try and*predict engine problems.......a bit of a horror story since he ended up doing a complete rebuild after less than 1600hrs, in spite of high levels of contaminents detected after only 800hrs., and following Cat's advice on what to do about it. Scary stuff.

Nick

Nick,
You can take this advice to the bank, and I mean it. Before doing anything else call Tony Athens at Seaboard Marine (sbmar.com to get his number). DO NOT let a mechanic touch your engine until you talk to him. He can be abrasive but he's straight forward and knows more about Cummins engines than anyone else, including probably Cummins themselves. Until you get a handle on things talk only to Tony. He is the most respected moderator on boatdiesel.com


-- Edited by timjet on Tuesday 26th of July 2011 07:45:39 AM

timjet wrote:Nick,
You can take this advice to the bank, and I mean it. Before doing anything else call Tony Athens at Seaboard Marine (sbmar.com to get his number). DO NOT let a mechanic touch your engine until you talk to him. He can be abrasive but he's straight forward and knows more about Cummins engines than anyone else, including probably Cummins themselves. Until you get a handle on things talk only to Tony. He is the most respected moderator on boatdiesel.com

Click to expand...

*Agreed.* Good advise.

** I think ileonard is on the right track, the engine is not getting enough air, check the air filter, the complete air system from filter to intake manifold, is the turbo working, do you have a boost gage telling how much boost you have and last but not least is the blow off valve stuck open. If you do not have an air filter could the engine have sucked up a rag and lodged it in the turbo? With the engine running excessively rich it will wash down the cylinder walls and force diesel into the crankcase.

While there might be a shortage of boat diesel mechanics in your area, I bet there are some good Cummins mechanics with a trucking company nearby. Helps if you know someone. I have called on truck mechanic near me (his boat has a Cummins like mine) and been well served.

Sounds like a compressed air hose from your turbo is leaking. I have seen the clamps blow off. Especially when they get old and the rubber shrinks.

Do you have a boost gauge? If so then that will give you and answer on lossing boost, If not then you have to look at the system and see if you have burst or leaking hose.

good luck.

If you did not mention the oil level going up I would have thought you lost a seal on the turbo. This usually happens on equipment where the air filter is allowed to get dirty. This is because the clogged filter causes a suction at the turbo and draws oil past the seal in the turbo. This is diagnosed by removing the hose between the turbo and engine and looking for being soaked in oil.

But you said you are gaining oil. Smell it and feel it. It will most likely smell like diesel and feel thin. When you said it sounded like it was running on five cylinders it made me think that you do have an injector problem. This too can be simple to diagnosed (providing it does not have electronic injectors) by staring the engine and using a wrench to crack open the injector lines one at a time. You engine should lope or miss when you crack the line as if you removed a spark plug wire from a gas engine. The injector that does not cause the engine to miss when the line is open is the bad one.

Other things that can add oil to your engine would be a fuel transfer pump or if you have a hydraulic or power steering pump installed on the engines. But unless it is way over filled with oil I dont think you would know the difference, and the fluid for the pump would be low.

One last thing, dont run the engine long with a crankcase full of diesel oil. It we cause wear on bearings and the cylinders.

That increase of oil in engine had me wondering. I don't know what kind of lift pump that engine has but I doubt if it is the mechanical diaphram type and even so it would be a double diaphram marine type.

Maybe a bad injector would dump that much fuel into the engine.

Whatever your problem turns out to be, and the fix, please post it for us Cummins owners to stash away in the memory banks.

*

cd30ketch

"Other things that can add oil to your engine would be a fuel transfer pump."*

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I said the same thing. . . *I had a fuel lift pump fail and as they are marine, there is no vent hole and a single diaphragm since they are diesel and not gas. *I also had an exhaust valve lifter come loose, same result except it smoked like a chimney and in both cases loaded the crankcase up with diesel.

Yeah, me too. *I hope he posts what it was.

The 330 BTA should have a piston type lift pump. Those on a truck are not prone*to failure like the diaphram pumps are.

*


-- Edited by jleonard on Monday 1st of August 2011 07:43:16 PM

I failed to mention one other source for diesel in the crankcase and that is the injector pump front seal. The missing on one cylinder points to an injector but if you determine that the injectors are good do yourself a favor and change out the lift pump before spending $$$$ removing and repairing the injector pump.

Thank you for all the tips, guys. While waiting for the Cummins tech. to show up (from Ottawa), I believe I've determined there are no issues with the turbo, aftercooler, valves (checked clearances...all within spec.), no evidence of any blowby, installed a new air cleaner. I'm awaiting the oil analysis (found a very helpful*local truck shop that is a Cummins agent......they are not allowed, however, to make "house calls"). Everything is pointing to an injector issue, which was my "gut" feeling when it happened:*they need to bring those in from the USA hence the delay in the service call. Hopefully she will be up and running by this Sat., when we had planned to head to the thousand island area of the St. Laurence River for*our months holiday.

Again, thanks for all the advice, I really appreciate the support.*I don't have an Internet connection at the marina so rely on the local McDonalds wi-fi. Will post the final outcome.....good or bad!

Nick

jleonard wrote:
The 330 BTA should have a piston type lift pump.

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******** Without offending you, how can I confirm that, indeed, the 330B has a pston type lift

******** pump. Are you sure?