31' Bertram--Need help w/ Yanmar 4LHA-STP Issues

[jackryan]

I have a 1978 31' Flybridge with a pair of 240HP Yanmar 4LHA-STP's with just over 500 hours. The engines are 2004 model year. Great (if not one of the best) engine packages for the 31 Bertram. I need some help diagnosing an issue I have recently started to encounter with my Yanmars. The engines run fine at lower RPM and accelerate normally up to about 1600-1700 RPM with just a little white smoke/steam. When I push the throttles past the 1700 RPM position, the engines begin to put out copious amounts of dark smoke and accelerate very-very slowly up to about 2500 RPM. Beyond 2500 RPM they again begin to accelerate normally and appear to run fine, with just a little wisp of white smoke/steam. The engines only run up to 3100 to 3200 rpm, and I think they used to run up to 3400 to 3500 RPM.

I have changed the racor's and checked the engine fuel filters. The housing and through bolt for the engine mounted fuel filter do have an odd black scaling on them. (I have not changed these filters yet). I had a diver clean the bottom this past winter, and jumped in to check it out yesterday. It has a little algae, but not too bad.

I have never done anything with the injectors, so was thinking that that may be the issue, but thought it was odd that both engines started acting like this at the same time.

Any idea as to what might be causing my issue?

Also curious as to what the scaling is on the inside of the engine mounted fuel filter and through bolt? Could this scaling have gotten past my engine fuel filter and clogged the injectors?

Thanks in advance for any help!

JR

[Yannis]

Hi Jack,

I too have the same engines and 300 hrs (2007 model).
I too have seen black smoke this summer from the port engine only, however without this rpm hesitation that you're mentioning.
I suspect the fuel filters, but lets hear from the more experienced.
As for the scale on the engine mounted filter, is it solid or slimy? Could it be diesel slime?

Please tell your brother that my solars are working fine !

Regards,
Yannis.

[Kevin]

Check your air filters. I think lots of black smoke means plenty of fuel, but could be short on air. The real mechanics can confirm hopefully.
Bottom growth will easily reduce your WOT RPM.
Maybe bottom growth is enough to overload while getting it over the hill up to cruise rpm?

[Rawleigh]

+1 on an air restriction problem when you have black smoke.

[jackryan]

Thanks for the responses. Thr scale on the filter housing and through bolt is not the slimy stuff-it's black and hard to scrape off. I've tried to buy new housings, but I'm having issues with the local parts distributor. I'll check the air filter, but on this model, the air filter is just a small, sponge like membrane that doesn't seem to pick up much. Also, if it was the filter, it seems like I would have issues at the higher RPM's too. They run beautifully once I get them over 2500 RPM's. Boats being hauled for bottom job and maintenance in the next couple of weeks.

JR

[Kevin]

Once the boat is over the hill or on plane the load percentage is probably less, despite the RPM being higher.
Also I recall reading lots of prior posts about those yanmar sponge filters collapsing and even falling apart. It might be worth upgrading to reusable filter.
If you have nmea outputs on your engines hook them to your multifunction display. The data you get with modern electronic diesels is really helpful for analysing this sort of stuff. Best thing I ever did on boat.

[Bill Fuller]

Jack and Yannis,
As Kevin said, you do not have a lack of feel but a lack of air.
So first question, Have you had the running gear thoroughly cleaned, the actual bottom is less important but also needs to be clean.
Here in Southern California I have to have my bottom cleaned every month. If you skip a month the boat may not be able to even get on plain. So have the bottom cleaned before you spend a bunch of money on other things.
Next question, Have either of you taken apart and cleaned the after coolers, heat exchangers, oil cooler, and gear coolers? If not after about 10 years for both of you, you need to do so. A dirty after cooler can definitely contribute to what you guys are seeing. I fresh water flush my motors after every trip and take all of these items apart every 5 years.
Next, 1700 RPM is the "magic" number where the engine has to have the turbo working in order not to generate a lot of black smoke. But, usually, at least in my experience, if the turbo is completely stuck, you will not go above about 1700-1800. Any way, check to make sure the blades turn freely and that the air side is completely clean.
I would strongly recommend that you both get rid of the stock Yanmar air filter/silencer. They have been known to come apart and chew up turbos.
Jack, the scale on the inside of the fuel filter housing is very bothersome. And I think you need to investigate what it is and how it got there. First thought is that your primary filter is not doing the job. What do you have for filtration?
So, here is what I would suggest:
Clean the bottom and especially the running gear. And see what happens.
Check out the air side of the turbo
Clean the after cooler

And see where you are after these items have been taken care of.

Also, both of you should visit sbmar.com and read the articles on after cooler cleaning, as will of some of Tony's other maintenance articles. There are written for Cummins but apply directly to out Yanmars.

FYI, I have year model 2000 4LHA-STEs,( same exact motor as the STP) with 15 years now and just under 4,300 hours. Injectors never touched. Seaboard Marine's Air filters.

Again Jack, that scale is troublesome. I have never seen anything like that. Please let us know what your primary filtration is. And maybe post a picture of the scale.

Bill

[jackryan]

Bill,

Great stuff, thanks. As for my filtration, I have Racor system. I change the filters religiously. (I think the filters are 10 microns). The second stage fuel filters are the ones on the engines. I believe those are 5 micron. I'll check the microns and post them here next time I'm on the boat.

As you suggested, I'll remove the stock air filters and replace with seaboard marine air filters and make sure the bottom and running gear are thoroughly cleaned. I'm pushing back for a trip to Japan, but I'll post the results as soon as I take care of those things. As for the scaling in the filter housing, I have no idea. I'll try to post a picture of them. Strange thing is, there is no scaling in the primary filters (racors). I would think those would have scaling too?? Maybe the filter housing had some sort of paint on them and it's worn/corroded??

John

[Yannis]

Thanks Bill,

Removed air filter, turbo turns fine. Engine hatch open, still black smoke, not much, but more than last year and more than stb engine.
So, probably I should remove and clean all heat exchangers, right?
I thought that I should try the fuel filters first as its easier, but then again, 10 years its about time I did the exchangers...

[Anthony]

I had a similar problem recently, pulled injectors and had checked turbo was fine had plenty of air, fuel was good. Could not make full rpm on port side I swapped props went from 20x20 4 blade with cup to 20x20 3 blade and all problems seemed to go away I still have black exhaust water on the port side but no smoke. I think the dirty water is left over residue. Now both motors turn 3400+rpm I lost 2 knots at cruise with the different props I'm not sure if I fixed the problem or not.
Anthony

[jackryan]

My brother went out to the boat to check the air filters and he found that they were extremely dirty. I'm hoping that was part of the problem. I'm guessing the dirty air filters along with the dirty bottom and running gear may have combined to cause the smoking and slow acceleration. I'm going to order new air flitters and change the engine fuel filter as well. I'll report the results after I am able to get those things done.

Thanks again for the help,

JR

[jackryan]

Here's a photo of the air filter. Ouch!

[jackryan]

Here's a pic of the inside of the fuel filter housing. Any guesses as to what is coating the filter housing? It's not slimy-it's some kind of hard scale that's tough to scrape off:

[jackryan]

On a better note, here's a picture of Jack's 9th birthday party on the boat last week and tarpon fishing on Lake Pontchartrain the next day.

[mike ohlstein]

They aren't adding ethanol to your diesel, are they?


Hey…….

i don't see any skinned knees. Those kids aren't playing hard enough.

[Rawleigh]

Or biodiesel?

[Rawleigh]

What tank do you have, metal or fiberglass? You haven't run any biodiesel by chance?

[Charlie J]

that filter is clogged up
I change mine every oil change
at 100 hrs
as for the fuel filter, it looks like its burnt on
never seen anything like that

[Kevin]

Could it be some type of algae? The only time i saw algae in diesel it looked like coffee grinds at the bottom of the filter.

[jackryan]

As far as I know, there has never been any ethanol or bio diesel in the boat. I've been changing the engine filter every 100 hours and the racor's about every 50 hours. I still have the original fiberglass tank in the boat. The inside of that filter housing has me stumped. I'm almost thinking that it may be a problem with the design of the filter housing. It looks like there may have been paint on the inside of the housing that has started to wear off.

I'm off to Houston on Saturday for B-787 Dreamliner training. I probably won't be able to do much until late October when I finish my training cycle.

Thanks for all of the help,

JR

[Bill Fuller]

Jack,

A couple of thoughts:
I don't think there is a design problem. I have been around a number of 4LHAs, including my own, and I have never seen or heard of this problem.
As Kevin mentioned it could be growth, or it may be rust. Either way I think your primary filter system may not be doing the job. And there is a good chance you have moisture in the on-engine filter.
When you have time, try placing a little acid on the material and see what happens. If it reacts then it is rust. I would use phosphoric acid for this test (a must for rust from home depot).
So far as fixing the filter housing, take it to your local machine shop and have them bead blast the inside. It will come out perfectly clean. The appearance after bead blasting may point to what the material was.

My 4LHAs have been in the boat for 15+ years now with just over 4,300 hours. I have changed the on engine filters numerous times and they have always been spotlessly clean.

When you get back and are ready to address the issue again and you have a chance to do the acid test, report back so we all can try to help you get to the root of the problem.

Bill

[Hyena Love]

Its likely some sort of algae/sludge. I had it, albeit to a far lesser extend, when I changed my on engine filters. Bunch of it in the filter itself, and a smaller bit on the housing. I forget what I cleaned it off with, but it was likely alcohol, diesel, or CX. Underneath it, there were indications of water being in contact with the housing. I'm not saying it was pitted, but the surface was roughed up and the paint damaged.

[Rawleigh]

Try putting them in a bucket with regular ethanol gas (or better yet E-85 gas, if available) and see if it won't dissolve it.

[SteveM]

So Jack, what was the issue? Was it air filters?

I'm having an issue right now. Only gets up to about 2000rpm then black smoke if I push the throttles farther.
I have 315 6LP engines.
Bottom is clean, props are clean.

Will check air filters after reading this thread.

Steve