My '88 (1300 hours) has just recently begun giving off some smoke and I noticed looking behind the boat that fuel is coming out of the exhaust. I can see the black fuel in the water. Boat starts fine, runs fine and is not overheating. (I've previously sorted out the hx and am pretty sure that is not an issue.)
Should I just replace the injectors? Check the valves for adjustment? (Or hire a mechanic to further diagnose.)
Any insight appreciated.
Kurt
Kurt : You aren't going to like my answer. Your engine has not been run enough - you have less than 50 hrs/year over 26 years!!
I'd get a mechanic to look at your injectors/injection pump for excessive fuel (reason for black smoke)
A thought
Ouch! Not the answer I wanted to hear...with 550 hrs on my 1990 boat. I was thrilled that it had such "low" hours when I purchased..Ooops, maybe I need to rethink my bragging rights criteria.
Quote from: kurt on October 12, 2014, 08:59:48 PM
and I noticed looking behind the boat that fuel is coming out of the exhaust. I can see the black fuel in the water.
Kurt,
You didn't mention how much, nor how you know it is fuel.
Does it occur just at startup? If so, it could just be the crap in the muffler being blown out.
Fuel isn't black, but the exhaust gases are.
Hello Stu,
I guess I sail a bit too much (and motor a bit too little.)
I started the boat yesterday and upon startup saw some black come out of the exhaust initially creating a bit of a black sheen on the surface of the water, then idled fine. Lately though I see the smoke and black injected into the water only after the boat is well warmed up. Am starting to think it is showing the symptoms of being slightly overpropped - I get to 2800 rpm max, flexofold 3 blade 10x15. Next time out will try to examine the situation more closely at varying rpm levels. Thanks for the advice/thoughts.
Kurt
A couple of comments/questions (consider the fact that I am not a mechanic). As I understand it, WOT (wide open throttle) should be approximately 3,000 RPM. So check your actual RPM with a handheld tach to confirm 2,800 is all you truly getting underway. And at WOT, what is your true speed over the bottom (GPS) in smooth water slack/no tide current? I am considering the Flexofold 3 blade 15x10 for my boat, so am interested in your comment about possibly being over propped...
Noah has a good point about actual RPM vs tachometer reading RPM. There is the issue of optimum cruising RPM for your prop and engine. Based on your sail number, I would say you have a 1988 C-34 with an M25XP engine. This is what I have. With my fixed 3 blade Sailor Prop, my optimum cruising RPM is between 2,450 and 2,500 on my tachometer ( I am not sure of my actual RPM because I never tested it). My point however, is that in my case, if I increase the RPM above 2,500, my engine works harder, but I do not see any sustained increase in speed. I listen to my engine, observe the temperature gauge, feel the vibrations, and keep an eye on the exhaust from time to time. This way if I notice anything different, I can be aware of what is going on with my boat. Do this and then make up your own mind about your cruising RPM and engine load, and see if there is any difference with your smoke issue.
Quote from: kurt on October 12, 2014, 08:59:48 PM
My '88 (1300 hours) has just recently begun giving off some smoke and I noticed looking behind the boat that fuel is coming out of the exhaust. I can see the black fuel in the water. Boat starts fine, runs fine and is not overheating. (I've previously sorted out the hx and am pretty sure that is not an issue.)
Should I just replace the injectors? Check the valves for adjustment? (Or hire a mechanic to further diagnose.)
Any insight appreciated.
Kurt
Mis-propping the boat and loading up the engine can cause that, but that shouldn't be your issue!
ken
The advice of not running your engine at full throttle is important. There is almost nothing to be gained in boat speed between 2500rpm and 3000rpm but fuel consumption and engine wear.Maybe a fraction of a knot. If you are getting soot at 2500rpm then maybe you have a foul bottom and growth on the prop? If not then how smooth is the engine running? If it is not running happily then maybe a bad injector is your issue. That will lead to poor performance, soot and smoke but injectors are not cheap to replace or service. Investigate all your other options first. Changing injectors is a pretty simple job so if you decide to go that way then it is something you can likely do yourself.
Mak Tamblyn
Quote from: kurt on October 12, 2014, 08:59:48 PM
My '88 (1300 hours) has just recently begun giving off some smoke and I noticed looking behind the boat that fuel is coming out of the exhaust. I can see the black fuel in the water. Boat starts fine, runs fine and is not overheating. (I've previously sorted out the hx and am pretty sure that is not an issue.)
Should I just replace the injectors? Check the valves for adjustment? (Or hire a mechanic to further diagnose.)
Any insight appreciated.
Kurt
You can check to see if you have an issue with one cylinder, like a bad injector.
If you have one bad injector, you may not notice it (rough running), but you can narrow it down with this procedure:
With the engine running and warm, crack open the 1st injector line nut, listen for a change in RPM and smoothness, record your observations, retighten, and move onto the next cylinder. If you have an optical tach it helps.
If cyl A has a bad injector, you WILL NOT see a difference when cracking open that fuel line.
However if cyl A is bad, you WILL see a difference when cracking open cyl B or cyl C.
In other words, the cylinder on which you observe a "no change" -- is a bad cylinder.
Ken K
Thanks for the comments everyone. A new datapoint - my boat use to rev to 2850 per meter on boat. Now it can only go to 2400 and then I see the unburnt fuel pouring out via the exhaust. At cruising rpm of 2200, maybe a bit of gray smoke but power output seems fine. Forgot to check the idle max rpm. Still thinking fuel issue - maybe the high pressure fuel pump? Kurt
Quote from: kurt on November 01, 2014, 04:53:30 PM
Thanks for the comments everyone. A new datapoint - my boat use to rev to 2850 per meter on boat. Now it can only go to 2400 and then I see the unburnt fuel pouring out via the exhaust. At cruising rpm of 2200, maybe a bit of gray smoke but power output seems fine. Forgot to check the idle max rpm. Still thinking fuel issue - maybe the high pressure fuel pump? Kurt
Have you checked that all injectors/cylinders are hitting?
Ken K
Haven't done any diagnostics yet - just observing symptoms. Besides a bit of gray smoke, all seems normal at start and cruise rpm of 2200 which is making me scratch my head. I will check injectors and cylinder firing as suggested here soon and will update. Thanks for everyone's advice/thoughts. Kurt
Kurt : Pull your injectors and take them to a diesel repair shop. They will test them on the spray pattern and "pop" pressure. You may want to buy new ones (injectors) or have the old ones rebuilt.
(Mainsheet Tech articles written on how to remove and replace injectors)
If that doesn't solve your problem then you may want to look at your injection pump. Parts do wear out!
A few thoughts
Ron,
I'm a big proponent of troubleshooting to pinpoint (or at least potential eliminate) causes before starting to arbitrarily pull components or replace parts. That can be a disaster because you may never know what the real cause was, not mention the unnecessary hit on the pocketbook.
And then you may get a false sense of security (unless it happens again because you missed the root cause.)
Not exactly Ockham's Razor, but.... - Take the easiest route first. It takes 10 minutes (including getting two wrenches out of and returning it to the tool bag) to test if you have a bad cylinder/injector! And then go deeper from there if necessary.
Ken K
Thanks Ron and Ken. That is on the next steps list. Did some more symptom checking though today.
Boat idles to 3100 fine. Reverse at dock 2400 max and fuel in exhaust as before. Removed k&n airfilter - no impact to symptoms. Screwdriver to ear on the 3 injectors and they all sound the same. Noticed air filter was black with what appears to be oil or fuel. Was red not too long ago. Now thinking exhaust may be restricted causing too much back pressure as another potential cause? Elbow is only 6 years old - muffler and exhaust hose original. But cooling water seems to come out the back fine. Or does fuel in an air filter also arise with any cause of unburnt fuel including injectors? Maybe I am grasping at straws.
Kurt
Quote from: kurt on November 02, 2014, 09:56:00 PM
Thanks Ron and Ken. That is on the next steps list. Did some more symptom checking though today.
Boat idles to 3100 fine. Reverse at dock 2400 max and fuel in exhaust as before. Removed k&n airfilter - no impact to symptoms. Screwdriver to ear on the 3 injectors and they all sound the same. Noticed air filter was black with what appears to be oil or fuel. Was red not too long ago. Now thinking exhaust may be restricted causing too much back pressure as another potential cause? Elbow is only 6 years old - muffler and exhaust hose original. But cooling water seems to come out the back fine. Or does fuel in an air filter also arise with any cause of unburnt fuel including injectors? Maybe I am grasping at straws.
Kurt
Where does your crankcase breather hose run to? To the air intake -- is that the source of gunky KN?
Is the oil ok, level normal - ie, no fuel diluting it (leaking injector pump pushing fuel to the crankcase)?
Ken
Ken,
Breather tube runs down to oil absorbing pad under engine. Silver dollar sized black mark to where the tube blows. Oil engine level was perfect when I checked it when this symptom first arose.
At this point, I think I will check exhaust, then check injectors, then replace injectors or then have someone replace/rebuild injection pump...
Kurt
Kurt, consider using the fellow in Oakland that helped Dave Sanner: http://www.c34.org/wiki/index.php?title=Rebuilding_the_M25-XP
Bingo. Just pulled hump hose and exhaust riser is blocked right in front of the place where raw water injects.
Time to pull the 6 year old riser and either clean or get a new one.
Thanks again for everyone's help.
Kurt
Quote from: kurt on November 03, 2014, 07:36:32 PM
Bingo. Just pulled hump hose and exhaust riser is blocked right in front of the place where raw water injects.
Time to pull the 6 year old riser and either clean or get a new one.
Thanks again for everyone's help.
Kurt
Quote from: kurt on November 03, 2014, 07:36:32 PM
Bingo. Just pulled hump hose and exhaust riser is blocked right in front of the place where raw water injects.
Time to pull the 6 year old riser and either clean or get a new one.
Thanks again for everyone's help.
Kurt
Ahhh ha. Cool (soon)!
So plenty of water flow, as you said. I'm surprised that the engine would run well with the exhaust blocked.
if the riser is bad (6 years??) you might want to consider the Westerbeke water cooled-riser that I'm doing for two C30 owners. It's a "project" but worth it in the end.
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Ken
<<run well with the exhaust blocked.>>
Ooops,
I meant to say run at all with the exhaust blocked!!!
ken
Hello everyone,
I installed the new exhaust riser (from Catalina Direct) and the problem is solved/all is good.
The boat revs even higher now in gear - 3000 - with my 15x10 flexofold - whereas before it went only to 2850/2900. Interestingly, maybe this riser is a bit less restrictive. I did note that the raw water nipple doesn't extend as far into the exhaust pipe on this version.
Thanks for all your comments/help.
Kurt
Congrats!
Kurt : Bingo. Just pulled hump hose and exhaust riser is blocked right in front of the place where raw water injects. Time to pull the 6 year old riser and either clean or get a new one.
Think that you need to look at the old riser and find out what the "stuff" is that caused the blockage! Otherwise a 6 year old riser should not have failed or become clogged from normal use!?!
Was it stainless or black pipe riser?, carbon buildup?
Keep us posted
Ron,
I hear you on that. Engine starts/runs perfect with no smoke so think I'm ok on that front.
My theory is the raw water nipple extended a bit too far into the exhaust pipe which created a place for junk - carbon, salt etc to form.
Kurt