Hi,
the decompression lever on my newly (to me) purchased YSE8 is very floppy, doesn't return fully forward, doesn't seem like there's any spring in it, i hangs about midway, should it have a spring that brings it fully forward?.
It has a starter motor, is it only pushed aft just for hand cranking?, should I just fix it forward? But make the fixing removable in case of a runaway, how common are throttle runaways?
The engine oil is black as black, I presume you suck it out of the dipstick filler to remove old oil?, should I use SAE40?, that seems to be the most appropriate oil after doing a little research.
Also the toggle on the front of the motor, I believe it is the oil strainer or oil scrubber, the toggle doesn't move, should it?
cheers

Hi BM
the decompression lever on my newly (to me) purchased YSE8 is very floppy, doesn't return fully forward, doesn't seem like there's any spring in it, i hangs about midway, should it have a spring that brings it fully forward?.
There is a return spring on the rocker cover. these corrode , get gunked up with paint or corrosion or break.
They don't seem to return the lever to a positive position (?) when operating well.
Either way it doesn't matter so much because they float and if it doesn't return it is not a problem.
I have a lanyard connected to the lever. It runs astern, through a ring and then back to a home- made quick release cleat.
To hand crank start, I pull the lanyard, cleat off, wind her up by hand and release the lanyard for her to compress and fire. It is almost impossible to hold the lever back and crank at the same time. (see photos of this set up)

It has a starter motor, is it only pushed aft just for hand cranking?
Yep, shouldn't need it for electric starting.

how common are throttle runaways?
Not some thing to worry about,

The engine oil is black as black
Yep, useful stuff too.
www.seabreeze.com.au/forums/Sailing/General/Another-benefit-of-having-a-YSE-Yanmar

I presume you suck it out of the dipstick filler to remove old oil?,
Yep, I use a 12 volt diaphragm pump. Cheapie from China. dose a great job.

should I use SAE40?
Don't sweat it on the oil. Go for the cheapest multi diesel lube oil.
On many engines the oil specs are important, not so on the YSE.
I use oil for agriculture equipment (gasoline, diesel, and small engine)

the toggle doesn't move, should it?
Yes, it most definitely should. I would remove the filter and clean.
I get it three turns before every start.
On my engine I removed the (rotating) filter this year and inside was sludge and metal free.
Washed in kero and replaced. That was after a 4 year interval.

Will add a photo of what collects in there if you ignore it (and oil changes)
this is an engine I was given and stripped down for spares.Even with that neglect it was like new inside.





Lanyard connected to lever (slack)
Lanyard led back through a ring (slack)



Home made cleat
Decompressor engaged and cleated off

Thanks Gary, that's awesome information, much appreciated

hi

so I was under the impression that I had the YSE8, or so I was told by the agent when purchasing.

However after closer inspection it has a YSB12 plate on the back of it. im pretty certain they are nearly the same engine.

Mine does have a tendency to run off on itself about once every few months, Scares the pants out of you when it happens. my understanding is that it is running on its own oil. I can stall the engine by blocking the air intake but was wondering would the decompression lever also work in stopping the engine. I haven't tried it as its an awkward reach and in the moment you can't help but go with what you know. if the lever would work then I would rig up a system like you have to decompress.

I plan to get the engine stripped down at some point but have not had the time yet.

Hi PDins
From the outside both 8 and 12 are identical. Conrats on a win!

You should have a short breather hose from the crankcase (exiting under the starter motor) and one from the gearbox.
If they are running into an old PET bottle or something you should have a pretty good idea of how much oil is being exhausted by blowby pressure.
Mine was just exhausting onto the inner hull and dribbling down to under the engine when I got her.

If there is not much (and they do blow out a mist) it is not running away because lube oil as fuel.
It is the linkages of the throttle system.

You can use the decompressor to stop it. Real easy to rig up a lanyard.
The other alternative is get a sink plug that is the right size and hang it next to the airintake.

gary

Gary

Thanks for the info. I'll check it over a bit this weekend when I'm out.

There is an old baking tray that is U set the engine that seems to capture a bit of oil. Do you think this could be the case.

If it is running on its oil what are the possible problems or fixes do you think.

I have to say, it starts every time without hesitation and is very reliable except for this once in a few months scenario. Also I should say it seems to be brought on by an increase in the throttle and then does not seem to respond when I wind the throttle back.

Hi PD
There is an old baking tray that is U set the engine that seems to capture a bit of oil.
I would extend the hoses and run them into a bottle somewhere. Much cleaner.

I have to say, it starts every time without hesitation and is very reliable
That would indicate good compression and thereby healthy rings.


Let's identify the problem.

Mine does have a tendency to run off on itself about once every few months,
If it is running on its oil

A runaway engine keeps increasing its revs until something gives or it is shutdown.
I personally have never experienced this and I have never met anyone who has.
I am not saying that it doesn't happen, but it is a lot rarer than people think.

The theory is that on the down stroke the crankcase is pressurized and on the up stroke the vacuum in the combustion chamber sucks lube oil up around worn rings and into the combustion chamber. The problem is, if the rings are that far gone, there will be limited vacuum in the combustion chamber to pull in lube oil.
Pressurizing of the crankcase should be alleviated by the breather tube. (with a little flapper valve or trap)

On a multi cylinder engine you can have one or two cylinders running away and sending the engine into that kind of death spiral.
On a single it is much less likely.


So to clarify, my question is
1. Are you are happily motoring along at reasonable revs and the engine takes off and revs faster and faster? ( a true runaway situation)
or
2 Are you motoring along at a decent pace ( for a YSE), you slip her into neutral and the revs remain high. Then you close down the throttle and the revs still remain high?

Which scenario are we looking at?

gary

Most four stroke pistons have oil rings and compression rings. Worn oil rings will allow oil to feed around the piston and into the combustion chamber. The excessive oil around the piston can aid worn compression rings in sealing compression gasses and maintain enough compression for ignition.

Oil rings sometimes consist of 2 scrapers and a crinkle, others can be a single unit.

A runaway engine is more likely to occur from a crankcase breather feeding oil back to the intake or in other cases when a turbo leaks oil into the intake.,,,, Rather than the oil being feed past the rings.

the decompresion is not on the engine to stop runaway,its to allow for easy turn over of the engine,it can help starting and turning over engine for tuning,i would only use for a runway as a last resort as you can dislodge push rods and cause valve piston contact .A engine will not usualy runaway from worn rings as the loss of compresion is of set by the extra oil ,but if the oil gets back in the manifold it can.most oil run aways are caused by oil entering the manifold by a faulty turbo ,egr or blower seals.fuel runaways are caused by jamed govenor linkages.I have seen 4 fuel runaways and 3 oil runaways

Select to expand quote

So to clarify, my question is
1. Are you are happily motoring along at reasonable revs and the engine takes off and revs faster and faster? ( a true runaway situation)
or
2 Are you motoring along at a decent pace ( for a YSE), you slip her into neutral and the revs remain high. Then you close down the throttle and the revs still remain high?

Which scenario are we looking at?

gary

Gary

you know this is a difficult one to answer. sometimes it has happened on startup and I think that the revs increase rapidly. However should note that I set the throttle for some revs to turn it over so this could be a case of it just coming up to speed.

other times yes I have been motoring along and then throttled back with no response from the throttle.

so its really hard to say. maybe the next time it happens (if it happens) I should reach for the throttle on the front of the engine before reaching for the air intake.

Grich64

Yes I do understand that the decompression is not designed for stopping the engine but it would create a scenario that I could rig something back up to the cockpit for quick action rather than having to throw myself down the companion way and rip the engine covers off, if you see my logic.

the previous owner did leave me with quite a few spare parts including what looks like a set of piston rings and a new head gasket. maybe the solution is to give the engine a really good strip back, overhaul, clean and go from there.

Hi pdins.
As you can tell I have time on my hands.

I set the throttle for some revs to turn it over so this could be a case of it just coming up to speed.
Yes. I star at over half throttle and when she has settle down throttle back.

I have been motoring along and then throttled back with no response from the throttle.

OK. from your description I think we can eliminate engine runaway and look at the throttle/fuel pump /governor linkages.

1. Throttle cable. If you have a Morse cable (usually red and of high quality), the outer cable sheath is held by a saddle with a dimple in it. Check that is is clamped down in the right position on the sheath end.
If it is not a Morse cable (my first boat with a YSE had a lawnmower or motorbike choke cable ), check the cable for smoothness of operation. If stiff, replace. Don't bother trying to lubricate it if it's a cheapy.

2. Fuel pump /governor linkages. One of the great things about a YSE is that even (for most owners) the scariest mechanical parts are repairable by a farmer in the middle of a rice field in the Philippines.
The pump and linkages are an easy fix/adjustment. Do you have a manual?
If not, here you go
www.sailingthanksdad.com/documentation/Yanmar-YSE-YSBServiceManual.pdf

Parts list has exploded view of parts and aids disassembly and repairs.
lsm-diesel.dk/2012/yanmar/pdf/motordele_yse.pdf

If you need parts Minards Diesel in Newcastle have stock and a reputation. (or at least they did have when last contacted)
www.minardsdiesel.com/

The instructions for resetting the linkages are on page 38, but are quite confusing for something that simple.
I have rewritten them for simplicity and clarity. Copy and paste this for further reference.
I tried to upload a PDF with better definition , but couldn't so you will have to live with this fuzzy one.

Especially note the mention that the eccentric pin thread should not protrude below the governor second lever.




gary

Gary

wow.. thanks for the detailed response.

Ill have a good look over all this at the weekend when in front of the engine and report back with any other findings.

Really appreciate the knowledge.

Gary, as you point out you may have time on your hands. That said your post are appreciated by one and all. Good on you

Thank you Woko. I appreciate you appreciation.
I am just handing on stuff that I wish I had known 40 years ago.

gary

One of the projects with my YSE8, is to put a new fuel tank in, currently there is a plastic 7.5L tank sitting on the port qtr berth, I'd like to put in something around 30L or so, is it possible to have the tank below the primary fuel filter, ie in a locker under the qtr berth, or must the tanks be above the filter/motor?,
as they originally had a small day tank bolted to the top of the engine.
cheers

All I know about these engines is that a mate has one on his boat and it starts every time even if it's left for years , I put a cut down gemini exhaust valve in it 25 years ago when the original one failed and that tiny tank on top seems to last forever. We changed the water pump impeller last year , cheap rubbish as they only last 20 years ??

, currently there is a plastic 7.5L tank sitting on the port qtr berth, I'd like to put in something around 30L or so,

is it possible to have the tank below the primary fuel filter,ie in a locker under the qtr berth, or must the tanks be above the filter/motor?,


Hi Blue Moon.
I still have lots of time on my hands,
is it possible to have the tank below the primary fuel filter,ie in a locker under the qtr berth, or must the tanks be above the filter/motor?,

I don't know at what level the primary fuel filter is mounted ,
You cannot mount a fuel tank below the top of the fuel pump banjo fitting and ideally you want to mount the tank as high as possible to give the fuel head pressure (the weight of the fuel pushing down the fuel line).
The YS Yanmars have no lift pump to bring in fuel against gravity.

currently there is a plastic 7.5L tank sitting on the port qtr berth, I'd like to put in something around 30L or so,
At the absolute maximum you will use 1.5 litres per hour. I give that figure with a very wide safety margin.
1.5 x 4 = 6 hours. Not too bad for day sailing. Can you fit a larger tank in the cockpit locker or somewhere out of the way.


I have the small day tank fitted to the top of the engine. It is probably about 7.5 litres.
I motored 200 miles down the NE coast of Japan adding 1 litre very other 2 hours and 2 litres every other hour.
Yep. Every 2 hours for 48 hours I opened the companionway, set up the funnel and hose and topped her up.
In commercial shipping there is someone in the engine room all the time so I thought dropping in and checking everything every 2 hours was reasonable. Still do.
I use clear fuel line. Run it low and then up through a filter to the pump.







Oldboy. Love your comment!!

Select to expand quote

BlueMoon said..
One of the projects with my YSE8, is to put a new fuel tank in, currently there is a plastic 7.5L tank sitting on the port qtr berth, I'd like to put in something around 30L or so, is it possible to have the tank below the primary fuel filter, ie in a locker under the qtr berth, or must the tanks be above the filter/motor?,
as they originally had a small day tank bolted to the top of the engine.
cheers

It's very possible to have fuel tanks below the fuel filter - fuel pump arrangement, the only issue would be adding a lift pump, a little 12v job would be the answer

Thanks obr, Gary and Woko,
yeah, the motor just seems to sip the fuel very economically, the issue is the current red plastic tank is located half way down the qtr berth, and it's not ideal to squeeze in there and refill it while at sea before crossing bars.
sounds like I should just get a bigger tank to switch out, (would prefer to keep it simple rather than add extra 12v pumps), and it is quite easy to see how much is in the tank where it is
cheers

Switch it out and maybe a filler tube to save the squeeze in there and fill it ?