ysb8, its drives me crazy!!

[MJH]

Originally Posted by Halifax Sailor

This issue started last season, no start when launching, finally started after 15 minutes countinuous tries. Was hard start when back at the marina so this is what I have done since. Launching again Monday for another season, somewhat same issue. Slow start, 30-90 seconds before it catches and slowly starts. It wants to start, gives thoise bumps like an almost start then back to just winding. It used to start 10 secs. I know that 30 secs doesn't sound long but the admiral needs a quick start like it used to, for her comfort.

1) replaced all fuel lines
2) new filters
3) drained old fuel, made me cry at the price of it but thought it might be the issue, so new fuel in tank, old fuel had no smell! thought that was a little weird.
4) new exhaust elbow and hose
5) rebuilt injector, third party so I know it's correct. Even had them check it again, proper yanmar setting, torqued the injector to 15 ft/lbs. new crush washer when installing.
6) blew out all fuel lines, including tank vent to ensure no blockages
7) rechecked valve lash, it's correct
8) checked the ball valve in racor filter, its clean and working, prime pump works as well
9) checked fuel pickup in tank, clear and working
10) turned on elec fuel pump, fuel at hp pump, no bubbles
11) no leaks in hp line

I have an elec fuel pump that filled filters and lines no issue.
When it starts, it runs smooth like it never has before, no smoke ( nothing out of the usual for a diesel), however the slow starting is making me crazy. A fwllow club member jsut rebuilt/calibrated his hp pump on a 2gm. Waiting for him to install so maybe thats my issue? grasping at straws here.

Any idea would be helpful

I agree 30+ seconds to start is too long and I would be concerned about burning out the starter motor plus you are draining the batteries unnecessarily.

I'm with skipmac on trying to understand how the engine is turning over; normally or slow. If your batteries are good but turning over slow then I would point to the starter motor/connections.

Since the engine runs well once started the issue is located with everything connected directly to starting.

Good Luck.

[donradcliffe]

Does the engine start right away when warmed up?

[Char99]

I had this engine and the starter became intermitant, I bought a replacement from Amazon and found I had to crank a long time to get it started. I finally bit the bullet and had the original starter rebuilt (at cost of more than double the $'amazon unit) No more trouble starting. Just seemed that the replacement starter did not turn her over fast enough.

[Wotname]

Originally Posted by Char99

I had this engine and the starter became intermitant, I bought a replacement from Amazon and found I had to crank a long time to get it started. I finally bit the bullet and had the original starter rebuilt (at cost of more than double the $'amazon unit) No more trouble starting. Just seemed that the replacement starter did not turn her over fast enough.

For others reading this thread.

Be cautious if fitting an aftermarket stater motor to these engines. Many cheaper aftermarket starter motors do not have the necessary internal oil seal on the shaft of the starter motor between the pinion and the rotor. As the YSE, YSB & YSM engines have a wet clutch, oil spray will enter the starter motor and make its way to rotor and then to the commutator making it perform poorly.

[Wotname]

Timing mark inside starter motor aperture.

[Rumrace]

Sounds like compression
I squirt a little engine oil in every stored cylinder.
If you take out each plug and squirt in 1/4 Oz of 20-50w engine oil in each barrel.
If it starts easy with smoke you hav worn barrel rings With the head off you can measure the lip on the barrels.

[Rumrace]

Enough can get your engine oil tested. It will confirm you have blow bye where compression loss allows fuel oil to contaminate engine oil

[Halifax Sailor]

Wotname and Paul, here's the pics to go with the update.

[Halifax Sailor]

oops got them this time.

[grantmc]

Originally Posted by Rumrace

Sounds like compression
I squirt a little engine oil in every stored cylinder.
If you take out each plug and squirt in 1/4 Oz of 20-50w engine oil in each barrel.
If it starts easy with smoke you have worn barrel rings With the head off you can measure the lip on the barrels.

YS8s don't have glow plugs and they're single banger with horizontally mounted cylinder. Quite difficult to test the compression as they have a pre-combustion chamber, and a control lever to decompress.

Really old motors. There were 3 different models produced E, M and another I can't remember. All were available in either 8 or 12 hp variants.
They all had the option of a hand crank (a sort of chain arrangement, and not a bad thing either), and so it wasn't unusual to find there wasn't a starter motor.

The cylinder head gaskets corrode on the down side because the motors are raw water cooled. And it's the corrosion that causes the reduction in compression. Replacing the gasket is just standard maintenance every 500 or so hours. It's a very simple job, and the only special tool needed is a torque wrench, shouldn't take more than an hour or so.

OP and others with these motors, you can take the head off without removing the injector. And I would encourage not removing the injector as it is quite tricky to get them to sit right and seal once removed. There's a special copper washer that must be replaced if taking the injector out, and the two little injector mount bolts bend really easily (but not so easy to spot).

[grantmc]

Originally Posted by Wotname

...YSE, YSB & YSM engines ...

Wotname nailed the 3 models. They are all almost identical and I found parts interchanged. If left original all have gravity fed fuel tanks sitting on top of the motor. Another great advantage that meant that if (when) you ran out of diesel no need to bleed.

[Rumrace]

Wow I had no idea. Just getting use to Yanmar is an education.

[Wotname]

While fault finding from photos is notoriously inaccurate, if I had to make a call, I would say the problem is low compression due to the circled spot.

[Halifax Sailor]

pics of the old gasket, many places that look like they could have leaked. One of them certainly cooresponds to wotname pointed out. Several other points look very suspicious. I did no damage when removing, was slightly stuck but surprisingly easy to remove the head. Going down with a camera and a mirror tomorrow see if I can spot anything inside the cylinder.

[Halifax Sailor]

Here's a pic of my ysb8. Very close quarters, under the stairs, as it was a repower sometime in the past. Original was a saildrive, You can see the patch inside and out. The yellow "bob" you see at the top is where I keep the ignition keys so I turn the raw water on and off. Can't start without keys and habit puts them back there everytime. Just makes me feel safer, thru hulls closed!!