Hi From Down Under

[Compass790]

Yes but it could be the engine getting flooded because of too much cranking with the starter motor if the engine fails to fire. You can flood the cylinder that way as well thru the exhaust valve as I said.
You can heat the liner a bit but I wouldnt go much above say 100oC at a guess.
It could be it has other problems but obviously first you have to unseize it

[Gregted]

Originally Posted by Compass790

Yes but it could be the engine getting flooded because of too much cranking with the starter motor if the engine fails to fire. You can flood the cylinder that way as well thru the exhaust valve as I said.
You can heat the liner a bit but I wouldnt go much above say 100oC at a guess.
It could be it has other problems but obviously first you have to unseize it

I see now what you mean. The engine is cranking enough to circulate water to the mixing elbow but not firing and blowing the water out allowing the exhaust pipe to fill and flow back into the engine..

I will have a closer look at the mixing elbow when we head back aboard.

I might also make a stainless elbow regardless. Is there any reason for the riser and elbow? I'm guessing that is to keep the exhaust above the water line.

The pic attached seems to not have a riser, so nothing to stop sea water flowing back into the engine.

I know this is for a different model, so the engine may be higher.

[Compass790]

Lost post 2x


Yes glad you understood my explanation how water can get in.
Elbow you pictured is off a vertical cylinder engine so yes higher.


You could google exhaust design or look in threads but basic idea afaik is to build riser so elbow is above exhaust hose loop.
You may not have the space to do that in your installation. The homemade exhaust riser & elbow I pictured isnt quite as high as I wanted but thats as high as could fit in.

The way to avoid water getting in is to have an instant starting motor ( easy to do on ysm12 with good compression & injection system) or do not open water inlet valve until motor starts.
Gotta go do someting now.

[Compass790]

Reading back through your posts I think your engine got flooded by cranking the starter motor over with no start as you said previous owner said it will turn over but not start.
Possibly he then realised water was getting into the motor so removed the water inlet hose.
Your boat will not go any faster with the inboard, assuming you have correct props on both, but it will be a lot cheaper to run & less obnoxious noisewise.
Both should easily push it at hull speed in flat water.

[Gregted]

Ok. So an update on the Yanmar.

We attempted to free up the piston with freeze and release but no joy.

I also tried again to turn the motor over with a stilson wrench on the crank shaft but it sounded like it was slipping a gear internally so we'll take the side plate off and see what's going on in there.

We decided the motor had to come out.

To achieve this, we had to cut away some of the seat frame and a small part of the cupboard under the sink.

We disconnected the prop shaft and the engine mounts and all sundry cables and sensors and out she came.

We also decided the placement of the dining table was taking up too much room so out that came also. That gave us so much more room to move. We might put a smaller table back later.

Pics attached of before and after the table was removed.

When I tried to tip the motor on its side, the gearbox oil drained out the hole where the starter motor was mounted to the bell housing, so I think we have to replace the front bearing on the gearbox because in a car, the gearbox oil should not have access to the bell housing, flywheel or starter motor.

I assume that is the same for a diesel marine engine.

We also removed the sump plate and in the pic attached, you can see the color of the engine oil and the rust on the conrod end.

I'll head back out in a few days when my back recovers and syphon out that sludge, disconnect the conrod and see if we can move the piston.

We also pretty much decided to move the sink from above the motor to the port side and just make up a removable box seat to cover the motor.

That will free up more room in the galley/dining room and make future motor repairs 100% easier.

[Wotname]

Originally Posted by Gregted

......When I tried to tip the motor on its side, the gearbox oil drained out the hole where the starter motor was mounted to the bell housing, so I think we have to replace the front bearing on the gearbox because in a car, the gearbox oil should not have access to the bell housing, flywheel or starter motor.

I assume that is the same for a diesel marine engine..........

Ahh - No, not for this engine. The YSM has a wet clutch so the oil in the gearbox has to have access to the bell housing.

This means (among other things), the starter motor shaft has to have an oil seal between the bendix and the rotor windings / commutator. If you see oil around the starter motor brushes, then the oil seal in the starter motor has failed or someone has fitted an (incorrect) after market starter motor without the necessary oil seal.

[Wotname]

Originally Posted by Gregted

Ok. So an update on the Yanmar.

We attempted to free up the piston with freeze and release but no joy.

I also tried again to turn the motor over with a stilson wrench on the crank shaft but it sounded like it was slipping a gear internally so we'll take the side plate off and see what's going on in there.

......

Thanks for the update. It sounds like good progress.

I'm not sure where you using the stilson as the crankshaft is not externally accessible.

You may be trying to turn the PTO shaft which is gear driven by the crank and thus turns in opposite direction to the crank.

You may be trying to turn the hand start shaft which is indirectly gear driven by the crank but it has a roller clutch that only allows torque to be applied in one direction; it slips in the other direction.

Have a look at page 1-16 and page 8-3 in the service manual.

Looking forward to the next instalment

[Compass790]

Given the rusty state of the big end I can see why you are having trouble moving the piston. I hear you with back recovery time needed.
Good progress & I too am looking forward to next installment.

[Fore and Aft]

Gregted here is another option if that Yanmar is beyond saving.
Cheers

[Gregted]

Originally Posted by Wotname

Ahh - No, not for this engine. The YSM has a wet clutch so the oil in the gearbox has to have access to the bell housing.

This means (among other things), the starter motor shaft has to have an oil seal between the bendix and the rotor windings / commutator. If you see oil around the starter motor brushes, then the oil seal in the starter motor has failed or someone has fitted an (incorrect) after market starter motor without the necessary oil seal.

Thanks for that. I was hoping we didn't have to rebuild the gearbox. The amount of oil that came out had me hoping it was a wet clutch.

Originally Posted by Wotname

Thanks for the update. It sounds like good progress.

I'm not sure where you using the stilson as the crankshaft is not externally accessible.

You may be trying to turn the PTO shaft which is gear driven by the crank and thus turns in opposite direction to the crank.

You may be trying to turn the hand start shaft which is indirectly gear driven by the crank but it has a roller clutch that only allows torque to be applied in one direction; it slips in the other direction.

Have a look at page 1-16 and page 8-3 in the service manual.

Looking forward to the next instalment

I meant the hand start shaft. I called it the crankshaft because it cranks the motor and I didn't know the correct term. I should have realized that term should be reserved for the actual crankshaft. Oops..

I found it does freewheel in one direction but I was applying pressure in the other direction but it won't budge.

Originally Posted by Compass790

Given the rusty state of the big end I can see why you are having trouble moving the piston. I hear you with back recovery time needed.
Good progress & I too am looking forward to next installment.

I thought that also. Maybe the conrod is rusted onto the crankshaft. I'll disconnect the conrod when I get back out and see whether the rings in the bore or the conrod is the problem.

At least now we have full access around the entire engine and can perform all repairs. Most without taking the engine from the yacht because it is a heavy mother and the yacht has a dogbox fitted to the rear of the cabin and access is very limited for any type of crane or winch system.

[Gregted]

Originally Posted by Fore and Aft

Gregted here is another option if that Yanmar is beyond saving.
Cheers

Thanks for that my friend. We will certainly keep that in mind if this one turns out to be a basket case.


If anyone knows where an artificial reef is required, keep me in mind.

[Wotname]

Originally Posted by Gregted

...........
I found it does freewheel in one direction but I was applying pressure in the other direction but it won't budge.
...........
I thought that also. Maybe the conrod is rusted onto the crankshaft. I'll disconnect the conrod when I get back out and see whether the rings in the bore or the conrod is the problem.

At least now we have full access around the entire engine and can perform all repairs. Most without taking the engine from the yacht because it is a heavy mother and the yacht has a dogbox fitted to the rear of the cabin and access is very limited for any type of crane or winch system.

My take -

Rings are rusted to liner (both are steel).
Conrod (steel) is keep away from (steel) crankshaft journal by bearing material which isn't steel so it won't be rusted together.
The position of the crank near BDC means a LOT of torque on crankshaft is required to move piston. If the piston was halfway between TDC and BDC, then the crank throw applies much more pressure to the piston for the same torque.
I'm fairly confident that a good blow on the conrod (after the cap is removed) will free the piston.

Now you have good access, you can wield that hammer

[Gregted]

Another thing we found yesterday was the sea-cock for the raw water inlet. Hidden down in the small bilge and so rusted, we didn't think it was a tap at all. Needless to say it won't turn off so we gave it a drink of WD40 and will leave it sit for a few days.

For some reason, the debris trap leaks unless it is perfectly level. It is raised as high as possible to fit under the sink but we might give it another six inches of hose to raise it a bit higher when we move the sink. Can't turn off the water inlet with that FUBAR sea-cock and I think in it's current state, if I crank on it, we might wind up with more water onboard than we'd like.

The lid Seems to leak more the more it is tightened.

Pic of a similar one attached. Only $50 ish dollars for a new one so that might end up on the list of replacements.


I did read another post somewhere that mentioned a wooden plug to fit any external inlets so I might have to equip the yacht with some of those.

Should be easy enough to turn a few up on the lathe.

[Gregted]

Originally Posted by Wotname

My take -

Rings are rusted to liner (both are steel).
Conrod (steel) is keep away from (steel) crankshaft journal by bearing material which isn't steel so it won't be rusted together.
The position of the crank near BDC means a LOT of torque on crankshaft is required to move piston. If the piston was halfway between TDC and BDC, then the crank throw applies much more pressure to the piston for the same torque.
I'm fairly confident that a good blow on the conrod (after the cap is removed) will free the piston.

Now you have good access, you can wield that hammer

Yeah. I was heading in that direction as well. The water from the exhaust valve would sit in the bore easier than flowing down and sitting in the big ends.

I should be able to get a decent whack, ( Technical term ), as you mentioned now that there is nothing in my way to restrict a decent swing.

Hitting up on the conrod end will also work much better. I worked out the piston is only about 20mm from bottom and that was confirmed by looking at the position of the crank when we removed the plate. 70mm above piston and a 90mm stroke.

[Fore and Aft]

Gregted, could you somehow brace the engine against a wall and use a hydraulic jack to push the cylinder down or up?
Cheers