Hi,

I have an old Yanmar YSE-8 and had a few issues with it. The boat has been sitting for about 2 years before I bought it recently.
I ran the engine only once for about 3 hours to get the boat from the seller to where I keep it now.

Since then the engine would not start again. There was smoke coming out of the starter motor. I removed and cleaned the starter motor that was full of old grease and put new brushes in and the starter now works fine.

I then tried to start the engine again and it would try and turn over but just didn't quiet get there. I bled the engine and noticed the screw to bleed the engine was worn and didn't seal / tighten properly anymore. I replaced the screw and washers and the engine now turns over fine.

I ran the engine for 10min and it ran fine and the water coming out the exhaust was clear.

I then put the engine into gear (both forward and back) and when I get the engine into gear I have oil or gas mixed into the water coming out of the exhaust with a bit of black smoke when I rev the engine.

Is this the head gasket or a cracked cylinder? Why does this only happen when I put the engine into gear?

Thank you for any assistance.

cheers,
Yamaha24ft

Hi Yammy.
Do you have milky oil in the sump?
You will have to pump out the oil to find out and after all this time it is probably time for an oil change anyway.

Gary

@Gary,

The oil looks good, not milky. So I don't think the water mixed with the oil - but the oil got in the water.

But yes, I was also thinking about an oil change first.

Hi Yammy,

I have had a Yanmar YSB 8, but have recently installed a YSE 12, as water back flowed into my cylinder and seized the engine, as it did not have an anti -back flow device fitted, nor a gate valve on the exhaust pipe. I now have both of these devices fitted.
When my YSB 8 was running well,without any issues, it was quite normal to get a little oil slick on the surface, after not starting it for 2 weeks.
All old engines will do this.
As for blowing smoke under excessive high revs that is also normal for the Yanmars of the era. It states thus in the manual and I confirmed this with a marine mechanic.
If you don't run your engine over 3/4 revs/throttle, you will notice, it will not produce black smoke.
They are a great little engine, with plenty of grunt for their size. Look after it and it will go for years...
Certainly do an oil change and check the sump.
I think your engine is fine.
PS. We reconditioned my YSB 8, as a spare engine and it will go for another 40 years !!
Cheers

I agree 100% with beam reach.
Oil that you noticed could very likely be excess diesel fuel that had built up when you were trying to start.

Yammy,
if my hull or prop are dirty I blow a bit of black smoke as I initially motor off my mooring, not a lot but you can see it. It disappears as the boat picks up speed. I think its referred to as "incomplete combustion"
Mike

My Volvo blows lots of blue smoke but i believe that is just a Volvo issue

Do you definitely have oil mixed with the water coming out the exhaust or is it actually in the sea water you are floating in?
Some time back I had black oily looking sea water and a bit of smoke when I was backing off the dock but turned out to just be barnacles flying off the prop when in gear and then being chopped up by the prop leaving the black oily water.

My mate has a ys8 in his boat , thirty years ago I machined up a Gemini exhaust valve to replace the original one that burnt out , yanmar wanted a bit too much. It sits for a few years these days before we go out and start it on occasion. Never fails to amaze me , a quick shot of wd40 and it always fires up , happy as.

@BeamReach thank you. That does make me feel a little less worried. However, I did run the engine for about 35minutes in idle and a few minutes in gear as I thought it might just have some built up but it continued to put oil and fumes out with the water. I will give it another try on the weekend and post an update.

Thank you everyone for your replies :) much appreciated.

Select to expand quote

Yamaha24ft said..
@BeamReach thank you. That does make me feel a little less worried. However, I did run the engine for about 35minutes in idle and a few minutes in gear as I thought it might just have some built up but it continued to put oil and fumes out with the water. I will give it another try on the weekend and post an update.

Thank you everyone for your replies :) much appreciated.

No Worries.. Give it an oil change..
This could be the cause?
Check snd clean the internal oil filter..
It could be the rings.. ??
How far down, did you have the throttle?
More thsn 75% ?
How is the temp, when you place your hand on top of the exhaust elbow? Should be cool, if not check the water pump impellor..
Minards Diesel in Sydney are the best for Yanmar parts. Luke is very helpful.
Cheers
Ps. Are you able to ask the previous owner, the history of the engine?
Make sure it at least has the anti- backlog vacuum device fitted.

@BeamReach thank you.

The engine actually does not have an oil filter so I need to pump the oil / drain it. I have yet to actually do this.

I tried the throttle in different positions, and as soon as I put the gear in the oil comes out. Even low throttle.

The exhaust as well as airflow intake all seems ok.

Thank you for the contact info for the Yanmar parts.

The previous owner had the boat for 1 year and he only used it once. He did give me a rundown and answered my text inquires but also can't really assist me further. He has been very nice and supportive though.

I do have another questions however, and this might be a very silly question. Can anyone tell me what this lever here is for? I can not find it in the manual or any of the documentation. There is an arrow drawn on it lightly that points up ?? and I have left it in the up position until I bled the engine, when I briefly moved it sideways (see image) and then back again pointing up. Could that have to do with it?

Thanks for any feedback :)

That is the internal oil filter brush. I was talking about checking and cleaning? The old manual says to turn the lever left and right on full rotations, a few times before starting a cold engine..It doesn't matter where this lever is positioned at rest. The last tine I checked mine, it was okay.
Moving the throttle slightly and getting excessive smoke seems an issue? It may need new rings and the piston barrel lightly honed.
The old school mechanic at Minards knows these engines. I would contact Luke and tell him your issues, they should be able to tell you the problem.
Cheers

Just a thought you said when you put it on gear oil comes out, perhaps the gearbox heat exchanger might be the culprit, how's the gear oil ?