Hi From Down Under

[Gregted]

Originally Posted by Compass790

Good advice from Wotname & skipper pete. If you are lucky the rings will be numbered with faint writing & the numbers go up. They wont necessarily exactly match the shapes in your Yanmar pic being aftermarket. From memory ( not to be relied on ) NPR aftermarket rings did not have the undercut on the 3rd compression ring. Wouldnt sweat on that as they work fine

Ill be interested to hear if top ring is chrome plated but will try to remember to ask the question when they arrive.

Still waiting on the rings to arrive but thought I would have a look on the ebay item to see if they have more details but no glory.


I did however notice they have sold 15K parts since 2020. The 987 I saw was buyer feedback so that gives me more confidence in the quality of their product and not so much in my ability to read the seller details correctly.

[Gregted]

The rings have arrived. Not due till 6th March so 2 weeks early.

The brand of rings is Crown and they look ok.

They are not individually packaged and numbered/labeled as some I have bought in the past but that is the price you pay for the price you pay.

The top ring is shiny and beveled on top and bottom, so no problems there. Ring to right in pic.

The oil ring is also a no brainer. No pic needed of that one.

Number 2 and 3 are however very similar.

According to the manual, the second ring should have a cutout on the top inner corner and be tapered on the outside.

The third ring should have an undercut on the outside bottom and be beveled on the outside top.

Neither of these rings have a cutout on the inner edge. I can however orientate them so one cutout is up and one is down.

One ring is 3.55mm wide and the other is 3.76mm as can be seen in the pics.

Not too worried about that as the specs state 3.6mm give or take 0.1 so that is in the ball park.

Also I'll have to find a finer set of feeler gauges. Mine only go down to 0.152mm or .006 inch and specs state ring to side groove clearance is 0.02mm or 0.00078 inch.

That is a tiny measurement and I assume as long as the rings move around the piston grooves freely, that should be ok

Ring end gaps are measured at 0.5mm so good to go there.

Not too sure how critical the inner cutout on the second ring is.

I have attached a pic of what I understand the second ring should look like.


What do you all think? Should I install these rings or contact the seller and wait another 3 weeks for the ring?

[Compass790]

Hi Gregted,
The rings normally come in the order they are meant to be installed. You can check with supplier but my best guess is the narrower ring is the 3rd ring & the cutout faces down. If the picture matches the piston the 3rd ring groove is shallower.
It looks like 2nd ring is manufactured wrong as its the edge closest to the piston that is meant to be narrower in factory drawing as you said i.e..

I think the best bet is to check with supplier but they will probably work anyway.
I havent got rings here to check but each manufacture can differ & they can change what they make too.
If you cant get any meaningful reply from supplier I would install them in the order & the orientation you show holding them in your fingers i.e. both cutouts facing down

[Gregted]

Some movement on the Yanmar.


I've installed the rings on the piston and honed the bore. It came up ok with a few marks on the sleeve, but should still seal good enough. Last pic...


Installed the piston into the motor and connected the con rod end and sump/cover plate/breather. Names are weird on horizontal engines...


It turns over nicely with no weird noises, so far so good...

Made a crank handle. Turns out that shaft is a bit smaller than 3/4 inch pipe with 2 cutouts for the side pins.

Good compression while turning over on the crank handle.

We realized the fuel pump must be still onboard so I gravity fed the fuel filter and bled all the lines.

While turning over, had fuel squirting from the injector line so the injector pump is working. Win no 2..

Squirted some diesel into the intake port and got a bit of smoke from both the intake and exhaust when I let go of the decompression lever.

After the crank handle slipped off while on full downward stroke, smashing my hand into the concrete, I decided to refit the starter.


Looks like I'm left handed until the swelling goes down. Should be fun when I have to go potty and wipe my but later..


Turned it over a few times on the starter but I don't think it was spinning fast enough.

Battery on jumper cables may have been a bit tired so put it on the charge overnight.

Made a tool to remove that strange nut that holds the pto pulley on and removed the pto pulley.

I just welded some pieces of 6mm/1/4 inch ish steel into a cage to hold that weird nut and some steel on the top side to jam a 1/2 inch extension bar and attacked it with the rattle gun.

Came off with no resistance and the pulley was removed with a wheel puller.

I'll replace that nut with a standard nut of the correct thread. I have no idea why that nut was shaped like that.

Decided to pull off the timing cover and have a look inside and glad I did.

The PTO bearing was seized solid with rust and the pto shaft was attempting to just turn inside the inner race, so steel on steel.

I pressed out the seal and bearing and will get a new one before reassembly.

Should make it a lot easier to turn over

While I had the timing cover off, I decided to clean and inspect the oil pump and filter and they look good.

Also gave me an opportunity to check the timing marks and they line up on both gears but don't seem to equate to anything on the flywheel timing marks.


In the right half of the pic, the flywheel is at TDC and the timing mark on the larger gear is about 12 o'clock and the smaller one is about 11.30.

[skipperpete]

It sounds like you’re almost over the finish line, well done. Most folks worry about getting a rebuilt engine started……. Most diesel mechanics worry about being able to stop em so either leave a ring spanner on the injector pump high pressure line or be prepared to block the air intake. If you need to do a lot of dead cranking, keep the raw water intake closed until she starts. If possible, make sure you have oil pressure before releasing the stop lever.

[Wotname]

Originally Posted by Gregted

......

After the crank handle slipped off while on full downward stroke, smashing my hand into the concrete, I decided to refit the starter.


Looks like I'm left handed until the swelling goes down. Should be fun when I have to go potty and wipe my but later..

OUCH!. Yeah, the starter might be a good idea...

I'll replace that nut with a standard nut of the correct thread. I have no idea why that nut was shaped like that.

Hmm... I had the same idea but after thinking more about it, I elected to accept Yanmar's design engineer might have known more than me. Here is my take (maybe it is horse dung...) - by the time you add a flat washer under a regular nut, there is not enough thread to protrude the required >1.5 threads past the nut. The Yanmar nut has threads running through the inbuilt washer so there is enough threads within the nut and there is about 2 threads protruding from the nut. Good engineering practice requires a couple of threads protruding from a nut.

But... it's your boat, you get to chose!

Also gave me an opportunity to check the timing marks and they line up on both gears but don't seem to equate to anything on the flywheel timing marks.


In the right half of the pic, the flywheel is at TDC and the timing mark on the larger gear is about 12 o'clock and the smaller one is about 11.30.

Yep, I wondered about this first time but that is the way it is!

[Gregted]

Originally Posted by skipperpete

It sounds like you’re almost over the finish line, well done. Most folks worry about getting a rebuilt engine started……. Most diesel mechanics worry about being able to stop em so either leave a ring spanner on the injector pump high pressure line or be prepared to block the air intake. If you need to do a lot of dead cranking, keep the raw water intake closed until she starts. If possible, make sure you have oil pressure before releasing the stop lever.

I've watched a few vids of runaway diesel engines and they look pretty scary. I've also garnered a few tips on preventing that.

Don't overfill the oil, block the air intake and a new one from yourself, keep a spanner on the injector pump fuel line.

I've noticed that the decompression lever moves far enough to allow the exhaust valve to hit the top of the piston if pressed to far.

Seems to be a design fault when some type of stop bolt on the rocker cover could prevent that.

There may be cable connection still on the yacht to prevent that.

The Yanmar is on the hard in my shed atm so no water intake connected for the initial starting and a short run. ( I hope ).

We are thinking of fitting a new stopcock to the seacock line anyway as the current seacock is rusted in the open position, so we may leave the cooling water closed until the engine starts.
This could be catastrophic if we forget to turn the water on, but seems to be the best solution atm.

An ideal setup would be a closed loop between the thermostat and the water pump until the engine reaches operating temperature and only then would the engine water run to the mixing elbow.

This temp may be too high for the rubber exhaust hose aft of the mixing elbow.

Another solution I thought of would be a high water alarm probe on the exhaust hose.

Of course we won't need any of these solutions because the rebuilt engine will start first time, every time.

[RaymondR]

"This could be catastrophic if we forget to turn the water on, but seems to be the best solution atm."

Been there, done that. The worst part is the embarrassment one suffers from whilst floating around in the middle of the harbour whilst waiting for the engine to cool down enough to restart it.

I take the ignition key out and hang it on the valve handle any time I turn the raw water inlet off.

[Gregted]

Originally Posted by Wotname

OUCH!. Yeah, the starter might be a good idea...!

Definitely a good idea for clumsy buggers like me.

On the brighter side of the pain... Turns out it is not too hard to wipe your but left handed. Who knew... Guess you're never to old to learn a new skill..

Opening a twist top beer bottle one handed is a different kettle of fish though...

Originally Posted by Wotname

Hmm... I had the same idea but after thinking more about it, I elected to accept Yanmar's design engineer might have known more than me. Here is my take (maybe it is horse dung...) - by the time you add a flat washer under a regular nut, there is not enough thread to protrude the required >1.5 threads past the nut. The Yanmar nut has threads running through the inbuilt washer so there is enough threads within the nut and there is about 2 threads protruding from the nut. Good engineering practice requires a couple of threads protruding from a nut.

But... it's your boat, you get to chose!

All of that is valid an correct sir! The jury is still out on the replacement of the " Yanmar Nut". Not that I would trust 12 of my peers. They are probably drunk, or suffering from early stage alzheimer's.

Dad joke of the day.....

Half of me says to stop drinking and the other half says, "Don't listen to him, he's drunk".

[Gregted]

Originally Posted by RaymondR

"This could be catastrophic if we forget to turn the water on, but seems to be the best solution atm."

Been there, done that. The worst part is the embarrassment one suffers from whilst floating around in the middle of the harbour whilst waiting for the engine to cool down enough to restart it.

I take the ignition key out and hang it on the valve handle any time I turn the raw water inlet off.

Great idea there. We thought about placing a note above the ignition key as well.

Seems some embarrassment comes with boat ownership. I've forgotten to insert the bungs a few times and wondered why my feet were getting wet and had to return to the boat ramp and retrieve them from the car while the family bailed to stop sinking while far too many people watched.

That's when you follow the penguins advice. Smile and wave boys, just smile and wave...

[skipperpete]

I just had a look at your “Yanmar nut” and noticed the nearby governor linkage, flyweights and rack connection on the injector pump, that should all move very freely, particularly the pump rack, if not…… you might need that ring spanner we dicussed earlier in case she gets away.

[Gregted]

Originally Posted by skipperpete

I just had a look at your “Yanmar nut” and noticed the nearby governor linkage, flyweights and rack connection on the injector pump, that should all move very freely, particularly the pump rack, if not…… you might need that ring spanner we dicussed earlier in case she gets away.

All those parts do now move freely. When I first removed the engine cover the fuel control rack was seized in place and the governor lever 1 and 2 would not move so it was a good thing I did remove that cover to have a peek.

I am surprised at how little movement there is in the governor lever 2 under operation.

Curiosity may have killed the cat but it probably saved a runaway Yanmar this time.

Also, just picked up a new pto bearing and seal. The new bearing is also sealed where the original one was open. I guess the original idea was for the engine oil to lubricate the bearing but the downside is that it also allows contaminated oil/sea water to enter the bearing.

[Compass790]

Make sure the breather plate is the right way up as well or that can cause a runaway.
I thought banana benders just bit the tops off beers