Diesel Problem Smorgasbord...

[Jtcf78911]

Hi all.
As excited as I was to recently get my O'Day 28 back on the water I was pretty rapidly deflated when prior end of season engine (M-12) problems re-appeared. I was hoping all the dry-dock work I had performed (basics - filled tank with new treated diesel, new gas filters, oil and oil filter change, new air filter, new impeller, etc. My journey on Saturday, mostly motoring as the winds evaporated, included the following:

1. Quick engine start and warm-up - all is good.
   
2. Good motoring for about 30 minutes and exhaust discharge looking a nice bluish white.
3. Whoops...engine starts some minor self-deacceleration...but no worries, it quickly regains normal operating power.
4. Hmm...now some black discharge coming from exhaust...but she's still running fine.
5. Oh-oh...big cut-out...nearly dying, but she recovers and off we go again...
6. Oh-oh...bit cut-out...and this time she dies. However, starts right back up and off we go again. Now the exhaust discharge is inexplicably back to the bluish white...and we run without event for a good 45 minutes...but...
   
7. Black exhaust returns and for the next 5 hours we are on pins and needles with long stints of normal running and the occasional periods of engine cut-out and near dying or dying.....

Somehow we make it to the mooring. My on-board sailing guide gave me the following possible smorgasbord of possible reasons for the engine problems:

1. Bad fuel - polish it...
2. Water in fuel - polish it...
3. Sediment in fuel tank dislodged - remove it...clean it...polish fuel..
4. Running out of fuel, i.e. faulty fuel gauge (it's fine)
5. Change fuel filters (I just did this)
6. Fuel pump going...slowly...do they do that??
7. You need to clean or replace the fuel injectors...
8. And...oh no...the dreaded rings have had it...!!!

Completely lost as to where I should even start, although logically the fuel tank makes sense...although certainly preferable from a cost standpoint to get at the real "cause" fairly quickly. As a new sailor really not a good idea for me to be heading through a mooring (or elsewhere) with an untrustworthy fuel system...

So again..primary symptoms are engine loosing power and the occasioned black discharge from exhaust..

Knowledge of the sailing expert masses appreciated.

Tx.

Tom O'Day 28

P.S. Operating temperature is fine.

 

[Joe5917]

Check the raw-water strainer for seaweed sludge. Could be that cooling water is running intermittently or insufficiently.
It may take some time for the temp gage to respond.

 

[Davidasailor26]

Black smoke and losing power does sound like potential overheating to me. When you say the operating temperature was fine - what was the reading? The gauge may be inaccurate. Also, how much bluish white exhaust are we talking, and at how much throttle? I don't really think there should be enough to mention from an M12 if the rings and temperature are fine.

 

[kloudie1]

The cutting out is pretty sure to be an air leak or not bleeding all the air out.. since it recurs, probably an air leak in the primary filter gasket or a fitting on the filter or the tank. Suspect anything on the tank side of the lift pump.

 

[Benny17441]

Just adding new treated fuel to a tank does not eliminate sediments or water in the tank. By the same token a new filter element can become fouled in a very short time if there is excessive water or sediments in the tank. My point is not take anything for granted, go back and review everything. Was once helping a friend to re-position his boat in anticipation of a trip. No sooner did the boat got into some heavy seas that the engine started loosing RPM and recovering. After a while it just died. I went below and drained the water separator and there was a ton of water. There were two spare filters aboard so I went ahead and changed it. The engine started right away and ran good for about an hour and then again started loosing RPM. This time just drained the separator but kept the same filter and the engine only ran well for about 10 minutes. Went below drained and changed the filter and got us another hour. After that with no more spares decided to just remove and eliminate the filter element. These diesel engines can burn fuel with a good amount of water in it so this time the engine ran good all the way to our destination. We were relying just on the secondary filter to take care of any sediments in the fuel. I had noticed the replacement filters were 2 micron which were too restrictive and eventually traced the water in the tank to worn gasket cap which was allowing some rain water to leak into the tank. Less restrictive filters, a fuel polish and a new gasket for the fuel cap resolved the problem. The water separator in doing its job was just quickly concentrating the water and fouling the filter element. Not saying this is your problem but just showing the effects of a dirty tank and how fuel filters can foul rather quickly. More than 80% of engine problems can be traced to the fuel system.

 

[NYSail]

Mixing elbow? Have you checked / replaced?

 

[Benny17441]

Engine overheating can thin the oil, lower compression and increase blow-by through the rings. Before these conditions evidence themselves the warning lamp and buzzer should be going like mad. Next time try placing the palm of the hand over the valve cover. If it is too hot to the touch that engine might be overheating. Check for excessive crankcase pressure by running the engine and removing the oil fill cap and hovering the palm of the hand over it. You should feel a slight pressure but if it is strong and in bursts then it might be excessive. Compression blow-by is also a function of the oil grade. A thin oil will allow more blow-by than a thick oil. As compression leaks down into the crankcase it will also bring oil into the combustion chamber causing smoke. The amount of oil will determine whether it is black or blue. As engines age they may require the use of a higher grade of oil or additives to improve viscosity. Always check the level and condition of the oil as should a rupture occur in the diaphragm of the lift pump diesel fuel can seep into the crankcase thinning the oil and increasing its level. You have an interesting set of symptoms that might indicate a compound cause. Perhaps some bad fuel with overheating or an air leak with a faulty injector, etc. Conduct a process of elimination, check the cooling system and all of its components. Check the fuel system for good fuel, clean tank (temporarily substituting with a portable outboard fuel tank) ,good fuel flow (filters and pumps), and no leaks (air/fuel). Anywhere you might see a small fuel leak is a possible entry for air into the system; most common check the gaskets on the bleed screws and the seals on the line connectors. Check the air filter intake tube for obstructions as well as the exhaust mixing elbow. The only engine killer possibility is a very low compression caused by worn rings or valve train and even those can be rebuild. Good luck.

 

[Gunni]

Mixing elbow? Have you checked / replaced?

I second that. It carbons up and you overheat. Didn't see that on your list of regular maintenance items. Lot of sailors forget the mixing elbow.

 

[Jackdaw]

Its been my experience that a clogged mixing elbow will give crappy performance from a cold start, and not have to warm up to be bad. A good way to check see what max RPM is; a clogged elbow will show maybe 70% of max even when cold. I'm betting Claudes on the right track.

 

[Stu Jackson]

OK, kids, let's get back to basics.

Most Universals do NOT have "mixing elbows" which those of you with Yanmars have. Universals have flanges at the back of the exhaust manifold and then have PIPES taking the exhaust gases back to the muffler, with a nipple welded into the pipe near the muffler. That pipe is called the exhaust riser on Universal engines. The nipples rarely get coked up, but rather the weld fails, catastrophically.

The link below explains lots of issues that the skipper in the OP should look for, even though it is written for M25 series engines, but just as applicable to his:

http://c34.org/bbs/index.php/topic,5078.0.html

If you read the link, it will help me to avoid retyping the basics of troubleshooting the issue the OP described.

Good luck.

 

[Gunni]

Well, they should have a mixing elbow! Is there a heat-shield that attaches to that red-hot puppy?

 

[Stu Jackson]

Well, they should have a mixing elbow! Is there a heat-shield that attaches to that red-hot puppy?

Yes, they are well insulated.

Like this:

http://www.catalinadirect.com/index.cfm/product/1889/exhaust-riser-assembly-c-34.cfm

My point, gunni, is that Yanmar calls it a mixing elbow, because it is just that. On Universals, the function is the same, but it is done differently, and called an exhaust riser, NOT a mixing elbow. That's all, just trying to clarify and use correct terminology.

 

[Gunni]

Thanks for that Stu, learned something new. I thought mixing elbows were near-universal on recreational boats. Is the exhaust riser bolted up to the engine for support? I have seen the Westerbeke engines but never noticed that pipe.

 

[Afrakes]

Not all Universals use a riser system and not all Yanmars use a mixing elbow system. There are hybrids. My 81' E-28 was refitted with a Yanmar equipped with a riser system and my 87' E-28/2's M-12 is equipped with a Westerbeke mixing elbow. Some boats have room for one system and not the other.

 

[odaydokay]

I agree, the OP has to check EVERYTHING now. I see a couple of things that maybe he did not check unless I missed them: Pull off the end of the heat exchanger and get any crap out of there such as water pump impeller teeth and other sediment. Blow out the hose from the pump into the exchanger also obviously. If there is a lot of crap, even pull off the heat exchanger and flush it. Also did he pull the bottom off the fuel pump and clean out that fine sieve? That must be done yearly. You can clean the tank all you want but that does not clean the fuel pump filter.

 

[Stu Jackson]

Is the exhaust riser bolted up to the engine for support?

Yes, gunni. If you look at the link I posted, the engine end of the riser goes into a flange, essentially a big female fitting, that is bolted with three (on my engine) studs and nuts. The other end is held up by a hump hose into the muffler.

Not all Universals use a riser system and not all Yanmars use a mixing elbow system.

True. I think I said most, but not all. If I didn't, I should have! [Just went back and saw that I had! ]

Also did he pull the bottom off the fuel pump and clean out that fine sieve?

Those fuel pumps should be installed after the primary filter. Most boats have it backwards from the factory.

 

[odaydokay]

When I bought my O'Day 28, then 10 years new, the owner ran only the factory pump with strainer and the motor mounted fuel filter. First thing I did was to add a Racor filter/oil/water separator. So pump with fine sieve, Racor, then factory filter. Not the order you suggested, but never an issue in the now 20 more years of operation.

 

[Stu Jackson]

So pump with fine sieve, Racor, then factory filter. Not the order you suggested, but never an issue in the now 20 more years of operation.

If you switch them, a simple task, then you no longer have to check the screen at the bottom of the pump. The purpose of the primary is to get rid of the stuff that can easily clog the smaller pump filter. Why depend on that tiny one as your first line of defense, when the Racor primary should be doing that?

 

[Jtcf78911]

Amazingly helpful guys. I'll try to respond in order:

• Joe5917 - Did pull and clean the raw-water strainer during my spring engine prep.
• David Sailor - I thought temp. was running around 160 degrees - I was bit preoccupied with in a free float mode. Will check again next time I'm on the boat. Was attempting to run full throttle...good looking exhaust was mostly white/clear with a tint of blue. Looked normal...then comes the black stuff... Didn't see a correlation between engine performance and what was coming out of the exhaust - of course that doesn't mean a correlation wasn't there...
• Kloudie - engine is supposed to be self-bleeding. Issue existed at end of season last year, and I changed all filters, so suspect it is not a filter issue. That said, I will check them and maybe replace just for the heck of it. Air issue a possibility - though I cleaned air filter (small as it is) and the draw tube. Air coming in elsewhere (where it shouldn't) may be the ticket...
• Benny - review everything seems to be the appropriate path. Pretty sure my racor was not full of water. Will do the hand compression test and change to a thicker viscosity oil. Like the fuel system bypass approach - would cut down the search zone.
• Stu - yep...no mixing elbow that I can see. Thanks for the link - will study it.
• Okay-Dokay - did nothing with the heat exchanger except add new pencil zinc. Maybe worth giving it a pull (sounds like fun). Will also take a closer look at the fuel pump. Maybe its on its way to dying but not ready yet...hence my throttling up and down... My fuel path is tank, fuel filter/racor, fuel pump, engine mounted fuel filter. Sounds like 10 micron is filter of choice, and pretty sure that is what I'm using.

Summary...sounds like I start pre-tank and work my way through the system... I didn't see any comment on possibly adding new fuel injectors? Worthwhile going directly to a compression test before tearing everything else apart? I of course would prefer this not be a ring issue...but...the engine is old...and black crap is coming out of the exhaust. May as well take a realist perspective.

Odd how the problem comes and goes...the engine literally is running at full throttle....slowly slows down...and then wham...slowly shoots back up to full throttle again...holds for awhile....up, down, up, down, die... Starts fine and then runs well for a time... I would guess the variability is a big clue...

I'll let you know if (when) I solve the mystery...or have to hire someone who can! Challenging enough to be a year 1 sailor ... I don't need engine problems to boot... That said...good learning experience and part of the fun of ownership...I want to be as self-sufficient as I can be...and maybe someday hand out good advice like each of you. Tx. again. Tom O'Day 28

 

[odaydokay]

I would do the easiest first. Get down to the fuel pump and twist off the bottom and pull the plastic strainer sieve out. If no one has been doing that, chances are it is sludgy. Also before pulling the whole heat exchanger out, unscrew the cap at the port end of it and get any junk out of there and remove then blow out the hose coming up from the water pump. You may be surprised what you find. The above will all take you less than 30 minutes.