Yanmar yse8 black soot

[Nuggs]

Hi I'm a novice with engines and have a problem with yanmar yse8 it's running fine but under load say over half throttle the water from the exhaust turns sooty/black smoke .in neutral it's fine .. there's no difference in power or anything I'm just concerned about the black looking water last week I turned back to the marina because I'm not sure what the issue is..any ideas folks many thanks

Here is s video of the problem

[a64pilot]

Engine is overloaded, most likely from a dirty prop or a prop with too much pitch

It could also be a clogged exhaust elbow, restricting the exhaust is similar to overloading

[Aswayze]

Wow, that's pretty impressive...

It's probably not overloading during the video there since it's obviously in neutral but quite likely you are building up exhaust soot at some point or another most likely due to a clogged exhaust elbow. I say that also because you can hear that the exhaust is a bit clogged as well judging by the tone. The original ones are cast iron and can get QUITE clogged. Such as this example here:



This will cause degradation of system performance...

Good news is there are stainless models available that really do work out much better.

That should get you right as rain to a certain degree.

I say to a certain degree because the YSE is always something of a sooty little motor particularly on sudden acceleration. It's based on a 1930's Coventry Climax engine and is a little unrefined. Most of the time, that is it's strength, it is dead simple and VERY hard to kill but it does not come from a time when people regarded black smoke and soot the same way we do now.

I minimize this on mine the following ways:

Slowly accelerate where practical.

Avoid crashing back and forth between forward and reverse and placing sudden loads on the engine with the throttle up.

Avoid prolonged idling, cruise with the throttle up where it gets to hull speed but not really beyond

Run the engine up a bit at the end of any slow speed runs.

Spray a mist of water into my intake when the engine is running periodically to keep the head and exhaust manifold from building up soot

Check my exhaust elbow annually. (Mine never really accumulates any soot now)

[Nuggs]

Thanks for replying I've check the elbow and that seems fine,maybe dirty prop I guess but have ti wait ti Oct to examine it because it's in the water

[AussieCat]

If the elbow is clean then my guess would be the engine has either not been run for awhile or more likely has only been run at low to mid revs.
This will cause a build up of carbon resulting in lots of oily looking black smoke.
Remember diesel engines need to work or you'll have problems.
Following are extracts from Yanmar operation manual.
a)

When operating the engine at low speed

for long periods of time, race the engine

once every 2 hours. Race the engine with

the clutch in NEUTRAL, accelerate from

the low-speed position to the high-speed

position and repeat this process about five

times. This cleans out carbon from the

cylinders and the fuel injection valves.

NOTICE: Neglecting to race the engine will

result in poor exhaust color and reduce

engine performance.

Periodically operate the engine near

maximum speed while underway. This will

generate higher exhaust temperatures,

which will help clean out hard carbon

deposits, maintain engine performance

and prolong the life of the engine.

b)

SHUTTING DOWN THE

ENGINE

NOTICE: NEVER stop engine abruptly

during operation. Yanmar recommends

that when shutting the engine down, allow

the engine to run, without load, for 5

minutes. This will allow the engine

components that operate at high

temperatures, such as the exhaust system,

to cool slightly before the engine is shut

down.

1. Reduce engine speed to low idle and

put remote control handle in

NEUTRAL.

2. Accelerate from low speed to high

speed and repeat five times. This will

clean out the carbon from the cylinders

and the fuel injection nozzles.

3. Allow engine to run at low speed

(approximately 1000 rpm) without load

for 5 minutes.

NOTICE: Continue to

hold the STOP button in until the

engine is completely stopped.

Just take it for a few good hard runs and don't be afraid to go to full throttle for short periods of time. I follow this procedure and have no smoke / carbon build up problems.

[Scubaseas]

Doesn't look like it's in gear in the video. Agree could be over pitched or dirty prop but you could also have dirty injectors. Video looks like classic exhaust "slobbering". Do you idle a lot? Do you rev engine 4-5 times to full throttle before shut down? Do you do a lot of short runs?



You might try a diesel purge/injector cleaning (https://www.amazon.com/Liqui-Moly-20.../dp/B00CPL8OVE Liqui Moly 2005 is excellent stuff)

[Compass790]

Wow! thats spectacularly bad.Lots of good tips here. I would go for blocked exhaust for a start. It's overfuelling but that can also be caused by injector & or injector pump problems. Also low compression. Does it start easily?
We have a YSM8 which did the same thing but not nearly as bad but it was lots of factors causing it but YSE's do it fast revving as Aswayze says. Better to fix the problem fast as the diesel will be washing the engine oil off the cylinder walls & contaminating yr engine oil badly running like that not to mention the fumes

[Aswayze]

Speaking of over fueling, you might check and see if someone had replaced your injection pump recently. The YSE and YSB both have a very simple pump and if you miss by one digit the part number, you can easily end up sticking a YSE-12 pump onto a YSE-8 which would cause a good bit of extra fuel to be added to the mix.

Similarly, the other likely thing to look at is the regulator on the top of the pump, It's the little valve that is acted on by the governor. In time, these can get worn and rather than smoothly ramping up and down the fuel rate you end up with a bit more of an on/off thing going on which would make it smoke like the dickens as well. I replaced my pump last winter because it was getting that way and was AMAZED at how much better it behaves now particularly since I am now again able to idle way down to a proper tickover speed where as before the engine tended to shutter to a halt if I idled down below about 700 RPM. The seemingly useless YSE-8 maintenance manual makes mention of some of this but as usual it's sparse in it's wording leaving you to sort of interpret what they are talking about.


Regulator is right here:



They are not commonly sold separately but they do show up from time to time. The manual seems to indicate that you can pull it apart and clean up the needle and seat to restore proper operation but I just replaced the pump for peace of mind on mine. I would generally not fiddle with a diesel injection pump, but again, the YSE and YSB are both VERY simple and basic units so you really are not going to goof anything up, fiddle away.


The YSM is the "Modernised" version and has a fancier pump in addition to several other upgrades.

[Compass790]

You can find the workshop manual here that shows the injection pump:https://www.sailingthanksdad.com/doc...viceManual.pdf

Wotname did his YSE8 injection pump up & bought the fuel metering needle from Yanmar AFAIK

[Compass790]

Originally Posted by Nuggs

Thanks for replying I've check the elbow and that seems fine,maybe dirty prop I guess but have ti wait ti Oct to examine it because it's in the water

Forgot to say did you look at the exhaust port in the head as well when you had the elbow off? Ours was quite clogged there too. You could pull the injector & see if that's spraying properly. Is the hull clean? They are not powerful motors & it doesn't take much to overload them.It's an old motor & could have multiple issues. Did the symptoms suddenly start or have been getting worse over time? Let us know what you find

[Wotname]

Originally Posted by Compass790

You can find the workshop manual here that shows the injection pump:https://www.sailingthanksdad.com/doc...viceManual.pdf

Wotname did his YSE8 injection pump up & bought the fuel metering needle from Yanmar AFAIK

Yep, I rebuilt my YSE8 injector pump (IP). It's a very simple IP and very straightforward to rebuild if you have an ounce of nouse.

There are three items that wear and all are available from Yanmar (or at least they are in Oz and SE Asia).

• The regulator needle valve
• The high pressure piston and housing
• The check vavle on the high pressure output side.

I found the manual to straightforward in the description of the IP and how to check for wear.

There are some copper crush washers and an o'ring. Reassembly while simple, has to done as per the manual or the needle valve can be damaged.

The IP (or it's immediate cousin) are still in use on new small diesel industrial engines in SE Asia so I expect the above parts will be available for a long time yet.

[Wotname]

^^
FWIW, the YSE8 IP regulator valve P/N is 171590-51420 and I paid $29 (AU) for it a year back.

IMO, this is the part most likely to wear in the IP (assuming clean fuel) and wear will cause over fuelling when advancing the throttle; but I'm no expert on these matters .

[Nuggs]

Thanks for all the advice just to clear in the video this happens when in gear forward and reverse,in neutral the water is clear I think maybe I'm going to look at the injector pump

[JimsCAL]

You don't have to wait until October to check if the prop is fouled. Get a mask and go swimming.

[stnick]

That engine is getting to much fuel ? she does not need all that ! might be cloged elbow, injection pump pumping to much fuel . Dirty injectors not able to spray a good pattern.
You can add marvel mystery oil to your fuel and the smoke will turn white ! But that will cover up your problem. !
You want to uncover the issue not cover it up !