Black smoke on yanmar diesel

[MIRELOS]

Check the oil dip-stick, did you put a tad too much oil, black smoke and engine racing not idling could be too much oil

[Captsteve53]

Black Smoke - is the most common one of three, and is really just an imbalance in the air to fuel ratio - too much fuel to not enough air. This means either too much fuel is being added to the mix or there's not enough oxygen being supplied to burn the fuel. The black smoke is full of particulates that are basically large diesel particles that normally would be burned as fuel. Any way you look at it, a diesel engine emitting black smoke is not going to be running at it's best performance,

Most common causes of black smoke are faulty injectors, a faulty injector pump, a bad air filter, in that order

Quite likely injector tips have corroded during sitting



Cheers Steve

[rweike]

I had the same engine with the same problem. I took it to the Yanmar dealer and he fixed it. It was clogged up exhaust system. They replaced one small part and cleaned out the exhaust elbow and it has run great ever since.

[BostonZee]

Hi! I had a similar problem with the Yanmar on my J/109 after about six years of owning her. At low RPMs the engine ran fine and drove the boat at normal speeds, but on end I went over 2,000 RPM it didn't matter how much throttle I gave her, the boat moved at the same speed through the water, and black smoke started coming out the exhaust. Turned out that the MIXING ELBOW had corroded on the inside, making the diameter of the pipe smaller, and while it was large enough to get enough through at low RPMs, at higher it was not. Replaced the elbow and my problems were solved immediately!!! You can often upgrade the part the a stainless steel version which does not corrode so it can be a one time fix.

There is a good article about it here: How to inspect a Yanmar GM exhaust elbow - Practical Boat Owner

Hope this helps!!

[tgv62]

Originally Posted by hobopacket

Compression test would tell you a lot. Black smoke is often oil being burned. Maybe valves are out of whack or piston rings.

Black smoke is NOT oil, then the smoke turns blue. Black smoke is diesel, seen that often when tractors pulling heavy weights up a hill, they spit black smoke.
Did you empty the dieseltank and put new in? Did you change the airfilter?

[ramblinrod]

White smoke is water (no sweet smell is fresh, sweat smell if coolant).
Blue smoke is oil (if no leaks and oil is down a litre on 50 hours is confirmed
rings or valve guides).
Black smoke is unburned fuel (if high RPM, overloaded, if low to normal cruise
RPM injectors need service (most likely) valves need adjusting (second) injector timing off (third).

[davil]

Skatun

if you do a search on this blog as well as other forums you will see how common black smoke and loss of power on Yanmars associated with exhaust system.
Personally I repowered my Tartan 34 back in 1999? with a Yanmar 2GMFW,with few hours before leaving San Diego same issue as described,tried most f what you did,eventually called a Yanmar outfit mechanic, the exhaust elbow was clogged!!!
Bought an extra elbow to carry as spare
New installed all was back to normal!

When pulled in Mazatlan again same black smoke etc.
disassembled and replaced with spare.
No more problems
cruised for 4 yeas using the engine 2 hours daily when at rest to charge batteries and the problem never recurred.
As stated,am surprised how often this issue surfaces.
If this ends up been your problem,and plan to go cruising,get a spare elbow as well as the hose pipe connector,it was a bear to unscrew it without a big vise.
good luck

[rpjn59]

Being over prop-ed will do that also, I believe.

[Kirie446]

I had a lot of black smoke coming out of my Yanmar 4JH3 TE when we first bought the boat. Turned out to be a plugged exhaust mixing elbow. Took a while to blow all the carbon out of the system, 4 tanks of fuel after replacement of the elbow.

[Qayaq]

Sounds like blocked exhaust. Maybe rubber hose has collapsed inside.

[soloauditor]

Originally Posted by skatun

I have black smoke coming out of my yanmar 2gm20, to the story its to be said that the engine were not started for 15 months.

What I have done so far is:

1. Changed oil and oil filter
2. All diesel hoses and filters
3. All water hoses are new
4. Removed exhaust pipe and looked into the engine seems ok
5. New antifouling, sinc anodes, saildrive gear oil change
6. Renewed starter and alternator
7. Changed vbelts
8. Changed the bleed pump
9. Tested opening pressure of injectors to ca. 145 bar open at the same time
10. Run the injector pump without injectors attached, seems ok
11. Adjusted valve clearance
12. Removed air filter, waiting for new one

So what should I do next? It seems to not be running on maximum rpm and also have problems running on idle in gear. My RPM does not work, seems to be the tachsensor(took it out no change in resistance when holding a spanner close to it) but I can not find a new sensor, any ideas where to get one? So I can unfortunately tell the RPM speeds.

1. So could it be the governor?
2. How to check this?
3. Should I lift the top off and check pistons?
4. Should I do a compression test?

if the engine was running well before the lay up water may have entered through the elbow and rusted the cylinders
.or when recent start up the engine perhaps hard to start, pumped the cooling water through the elbow and bent a conrod .if the engine was running well before the lay up forget the injectors and pull the head .if the engine was running badly before the lay up.check the injectors also check for glazed bores .

[Ted and Relinda]

Check inside exhaust riser and header to look for carbon buildup. That will cause backpredur and choke the engine causing black smoke. My problem was located in the riser where the water inlet into the pipe mixes with exhaust.. Ted.

[Jman]

Here is another quick thing to look for that had me stumped for longer than it should have.

Yammers, at least the 3gm have a primary fuel pump before the high pressure pump, it is rocked directly from the drive shaft (or manually with a little lever), and as such is in the oil pan.

Our had a pin prick hole in diaphragm that not only added oil to the fuel, but fuel to the oil.

Symptoms were exactly as described. Cleaned exhaust manifold, replaced injectors, etc. before discovering this.

[Infatuation]

My Universal did that and once it was the mixing elbow...the next time it was the check valve failing after the mixing elbow..[if you have a check valve after the mixing elbow, that is] exhaust back pressure will cause the fuel air mixture to run rich..

[Xthewater]

Originally Posted by AndyEss

Black smoke in heavy truck diesels often indicates bad injectors. You checking the injector cracking pressure was a good move, but the spray pattern may be bad and of too much volume (too rich causing the black smoke which is mostly unburnt fuel) because the valve seat or stem head is worn out and the metering is off. Cracking pressure should only indicate that the injector spring is still within spec and the seat is still good enough to seal properly when fuel pressure is below the cracking (valve opening) pressure. It doesn't necessarily say anything about correct fuel metering.

Nailed it! I'd also suggest timing may be retarded.